171 - Exploring Water Mist Systems with Max Lakkonen

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<v Wojciech Węgrzyński>Hello everybody, welcome to the Fire Science Show.

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<v Wojciech Węgrzyński>In our everyday job, modeling is one of the main tools Computer modeling or numerical modeling, cfd modeling these are the tools that we are mainly using in our performance-based design, and there are still some topics in the world of modeling fires that I believe are pretty rough, or I just approach with caution and one of such topics is modeling any water-based fixed fire fighting systems, such as sprinklers, dilute systems or water mist.

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<v Wojciech Węgrzyński>In this podcast episode, we will focus on the third one, the water mist systems, no matter how you distinct them high pressure, low pressure, water mist.

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<v Wojciech Węgrzyński>We're just going to talk about the water mist and we're going to talk about the challenges in how to model performance of such systems.

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<v Wojciech Węgrzyński>But you know me, it's not just going to be how.

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<v Wojciech Węgrzyński>The question why will occur many times in the interview, because for me, and the most important thing, is why we need to model, what we get from the modeling, what is the objective that we're trying to achieve and, if we are clear on that, how do we reach that objective?

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<v Wojciech Węgrzyński>For this episode, I have invited Max LekaLnen.

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<v Wojciech Węgrzyński>He's the managing director of IFEB and literally a few weeks ago, or even a few days ago, max has been chosen as the president of the International Water Mist Association, so congratulations, max.

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<v Wojciech Węgrzyński>It's a very good person to talk to.

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<v Wojciech Węgrzyński>I've heard him speak about modeling water mist multiple times and I'm sure you will enjoy him talking as well.

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<v Wojciech Węgrzyński>One more thing IWMA the Water Mist Association has also released a position paper on modeling water mist with CFD, and that position paper is linked in the show notes and is a very good companion to this podcast episode, as it captures most of the stuff that we wanted to convey through the episode in a written form.

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<v Wojciech Węgrzyński>So, without further ado, let's spin the intro and jump into the episode.

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<v Wojciech Węgrzyński>Without further ado, let's spin the intro and jump into the episode.

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<v Wojciech Węgrzyński>Welcome to the Firesize Show.

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<v Wojciech Węgrzyński>My name is Vojtěch Vyjgřínský and I will be your host.

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<v Wojciech Węgrzyński>This podcast is brought to you in collaboration with OFR Consultants.

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<v Wojciech Węgrzyński>Ofr is the UK's leading fire risk consultancy.

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<v Wojciech Węgrzyński>Its globally established team has developed a reputation for preeminent fire engineering expertise, with colleagues working across the world to help protect people, property and environment.

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<v Wojciech Węgrzyński>Established in the UK in 2016 as a startup business of two highly experienced fire engineering consultants, the business has grown phenomenally in just seven years, with offices across the country in seven locations, from Edinburgh to Bath and now employing more than a hundred professionals.

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<v Wojciech Węgrzyński>Colleagues are on a mission to continually explore the challenges that fire creates for clients and society, applying the best research experience and diligence for effective, tailored fire safety solutions.

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<v Wojciech Węgrzyński>In 2024, ofr will grow its team once more and is always keen to hear from industry professionals.

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<v Wojciech Węgrzyński>Who would like to collaborate on fire safety futures this year, get in touch at OFRConsultantscom.

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<v Wojciech Węgrzyński>Hello everybody, I am here joined by Max Lakkonen from IFAB, managing Director of IFAB.

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<v Wojciech Węgrzyński>Hey, max, good to see you in the podcast.

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<v Wojciech Węgrzyński>How about you?

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<v Wojciech Węgrzyński>So I've invited.

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<v Wojciech Węgrzyński>Max Lakkonen, the Head of Scientific Council at the IWMA and who came into the show is the president of the IWMA.

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<v Wojciech Węgrzyński>Congratulations on becoming the next president of the IWMA.

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<v Wojciech Węgrzyński>Thank you very much.

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<v Wojciech Węgrzyński>Any particular goals you have for this presidency?

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<v Max Lakkonen>Yeah, I'm not sure if we would have enough time for this podcast to go through, but definitely I'm having my own mission and I think we, as a society or industry, we recognize that there are a few things that we want to change.

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<v Max Lakkonen>We have all the chrono, so definitely some changes are going to happen during the coming season I'm looking forward for that, and also the scientific council.

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<v Wojciech Węgrzyński>You seem to leave it in the good hands of bogdan achenga.

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<v Wojciech Węgrzyński>He was also a guest of the fire science show.

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<v Wojciech Węgrzyński>I'm very happy with the developments in the international water mist association.

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<v Wojciech Węgrzyński>Uh, anyway, let's move, uh to the subject which is, uh, surprise, surprise water mist, and I've seen you talk about modeling water mist in the past.

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<v Wojciech Węgrzyński>I think you had a presentation about modeling in iw may in warsaw, which I even covered in the fire science show.

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<v Wojciech Węgrzyński>I know that you just hadn't talked about modeling water mist in antwerp in the iw may conference that was held literally in the last week.

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<v Wojciech Węgrzyński>So I thought, yeah, you're, you seem like a good guy to talk about modeling, and modeling is something my audience loves, so perhaps let's let's talk a little bit on modeling the water miss.

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<v Wojciech Węgrzyński>How about that?

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<v Max Lakkonen>yeah, absolutely, I'm.

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<v Max Lakkonen>I'm fine to to do that, but obviously I think modeling and water miss is a.

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<v Max Lakkonen>It's a quite complicated topic which we have recognized also as a as a society.

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<v Max Lakkonen>But I think it's also important to understand the fundamentals and how we have ended up to this moment that we are modeling water mist system.

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<v Max Lakkonen>But obviously there's many decades of work behind and also experimental tests, and I think that would be a good starting point, starting from not day one, but having the background and then ending up to the modeling which is nowadays too.

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<v Wojciech Węgrzyński>Perfect.

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<v Wojciech Węgrzyński>I actually appreciate this approach of modeling, rather than just dropping your random software obtaining colorful images but referring to experiments.

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<v Wojciech Węgrzyński>And boy, in the world of WaterMist, experiments is what you guys have.

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<v Wojciech Węgrzyński>Plenty of.

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<v Wojciech Węgrzyński>This is the entire industry.

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<v Wojciech Węgrzyński>Okay, let's start with the basics, or the fundamentals of water mist.

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<v Wojciech Węgrzyński>So how about we start with the definition, or where the water mist even came from?

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<v Max Lakkonen>Yeah, well, actually the definition is quite clear, so it refers to your droplet size.

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<v Max Lakkonen>So either DV90 or DV99 is less than 1000 micron, one millimeter, which obviously is a very, very broad definition.

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<v Max Lakkonen>But obviously it has some historical reason that some other technology did not really appreciate too much smaller droplets so they expanded that to quite wide range.

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<v Wojciech Węgrzyński>Is this dropletplet size for any particular reason?

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<v Wojciech Węgrzyński>Was it just a cut of points to distinguish what them is from sprinkle technology?

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<v Max Lakkonen>Yeah, that was the thing I mean.

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<v Max Lakkonen>I've been in the industry for 20 years now.

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<v Max Lakkonen>Depending on the task, sometimes I've been fully employed by that.

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<v Max Lakkonen>Nowadays I'm doing, let's say, part's say part-time misrelated things.

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<v Max Lakkonen>Also other technologies, but in the earliest, at the very first standards, there was different categories, also due to droplets, but that was actually cancelled and now it's a flat rate one millimeter.

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<v Max Lakkonen>But in practice the mis-IS technologies, they are far smaller droplets than that.

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<v Wojciech Węgrzyński>But couldn't you just define it with like K factors or pressures, operating pressures, yeah.

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<v Max Lakkonen>I mean droplet size.

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<v Max Lakkonen>That's really what defines whether it's a MIS system or not.

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<v Max Lakkonen>But then on the MIS system, there are basically low pressure, medium pressure and high pressure systems low pressure, medium pressure and high pressure systems and obviously depending on the technology they have a little bit of pros and cons to different aspects.

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<v Max Lakkonen>And traditionally high pressure systems they utilize the least water but they are having the highest pressure.

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<v Wojciech Węgrzyński>Can you indicate from a head what would be the average particle diameter for like high pressure or low pressure?

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<v Wojciech Węgrzyński>What the miss?

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<v Wojciech Węgrzyński>And then maybe the pressures for reference.

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<v Max Lakkonen>That's a too simple question to be made.

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<v Max Lakkonen>Oh sorry, because uh, and I think people who are doing modeling they would appreciate to get only certain numbers.

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<v Max Lakkonen>But we have to remember that miss technology is covering actually very different applications.

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<v Max Lakkonen>Sometimes they are more in the in the gas related applications and obviously there the droplets are very, very small.

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<v Max Lakkonen>And you can imagine that, regardless what is the pressure level, if you're putting a mist to a data center or inside the electric cabinet, it's a very fine.

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<v Max Lakkonen>But if you were would put mist.

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<v Max Lakkonen>Then the road tunnels.

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<v Max Lakkonen>So obviously there the droplets that they are much larger because they have to have much more momentum to it, the ventilation.

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<v Max Lakkonen>So that's that, let's say the introduction, but I would say that typically they are the range of between 50 and 250, 300 microns.

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<v Wojciech Węgrzyński>You see, I'm a practical guy.

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<v Wojciech Węgrzyński>If you gave me that number just straight off, I just put my liters per minute, I power my FDS and start earning serious money on modeling this, and I assume what we want to do in this interview is to kind of stop people from doing that without thinking.

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<v Wojciech Węgrzyński>So thanks for a reality check.

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<v Wojciech Węgrzyński>You mentioned in the panel applications you would have to have momentum to penetrate.

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<v Wojciech Węgrzyński>Now, that's also something I didn't always get in WaterMist, because I assumed that this is a distinguishing line between the Sprinkler technology and WaterMist technology.

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<v Wojciech Węgrzyński>Sprinklers would have those large droppers that penetrate.

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<v Wojciech Węgrzyński>They go down to the fuel, whereas in water mist you have something that basically acts in the gas phase itself, like wetting.

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<v Wojciech Węgrzyński>This surface action on the fuel is much more limited in water mist.

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<v Wojciech Węgrzyński>Can such simplification be made?

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<v Wojciech Węgrzyński>Or really, depending on what the most technology you can achieve, like the best of both worlds, the reality is somewhere between.

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<v Max Lakkonen>So you can't really gather corals.

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<v Max Lakkonen>Neither let's let's call sprinkler or deluge systems nor water mist systems.

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<v Max Lakkonen>So, and obviously typically within the tunnels, we are talking about very, very big fires.

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<v Max Lakkonen>So actually also the larger droplets they influence in the gas fade because they will evaporate no matter where you are pouring the water.

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<v Max Lakkonen>In same way also mist systems I mean, as I said, they are having relatively large droplets in tunnel applications and they do also wet it in insane sense than deluge system would do.

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<v Max Lakkonen>So germans would say that the answer is Jain.

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<v Max Lakkonen>So it's somewhere between.

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<v Max Lakkonen>But you know that, like 15 years ago, we had a long discussions with some other known people that whether the droplets would fly out from the tunnel with mist systems.

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<v Max Lakkonen>And obviously I think that the mist concept was not water mist but real mistcept was that the droplet sizes.

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<v Max Lakkonen>They were considered way too fine.

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<v Max Lakkonen>What are utilized in internals?

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<v Wojciech Węgrzyński>Can you broadly categorize the effects water mist has on the fire environment?

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<v Wojciech Węgrzyński>So if we want to model that like what kind of phenomena we would be interested in capturing?

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<v Wojciech Węgrzyński>What do they do to the fire environment?

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<v Max Lakkonen>well, basically, if we would have a kind of generic system so, and if we would say that we are having a generic fuel as well.

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<v Max Lakkonen>Traditionally mist systems, they're working three-dimensional, so they will fill the protected volume and then obviously the influence in the gas phase is having the major role, but a portion of the water will also collect on the surfaces, so it's also influencing there.

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<v Max Lakkonen>And then obviously one of the key things is obviously this extended or let's say, the very superior cooling effect by having high number of small droplets, the traditional big surface area evaporation and the way absorbing the heat.

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<v Wojciech Węgrzyński>And that cooling effect is happening in the gas phase.

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<v Max Lakkonen>It's in the gas phase.

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<v Max Lakkonen>Yeah, but obviously a part of the water will also go, depending on the application and how the droplets are tuned, will also go on the surface.

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<v Max Lakkonen>So prevent the re-ignition that will happen.

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<v Max Lakkonen>And then, the last but not the least, because there are also some applications where this is really tuned and for example, with flammable liquids, it's also the prevention of oxygen by the large evaporation, the local evaporation, so that will block the entrance of the fresh oxygen.

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<v Max Lakkonen>So, yes, the technology works in different ways and, depending on the applicator, different characteristic are more emphasized than the others.

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<v Wojciech Węgrzyński>Is it possible to even quantify what percentage of the water applied would evaporate?

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<v Wojciech Węgrzyński>Is this measured or perhaps a part of scientific research?

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<v Wojciech Węgrzyński>If zero was and no particles evaporated, 100% would mean that all of them evaporated.

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<v Wojciech Węgrzyński>What would be a ballpark estimation of a good water mist system.

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<v Wojciech Węgrzyński>I wonder how many of those evaporate actually, or again, it depends on the fire.

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<v Max Lakkonen>Yeah, I think you just said that it really depends on the fire as well.

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<v Max Lakkonen>It's very difficult to say.

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<v Max Lakkonen>In some of the test programs there has been also trials trying to measure this.

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<v Max Lakkonen>So measuring also the water which is collected on the surfaces and trying to evaluate that how much water was consumed, and obviously larger the fire is, more it will then evaporate.

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<v Max Lakkonen>So it's kind of proportional to the fire size.

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<v Max Lakkonen>But I would say that if we are having 50%, if we are having 50%, then we are really at the high end and typically you are spraying much larger area than where the fire is.

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<v Max Lakkonen>You are not very seldom, you are just targeting and it's more than the research where you are utilizing and you keep the things in control that you are trying to measure the evaporation rates that you are trying to measure the evaporation rates.

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<v Wojciech Węgrzyński>Another question the way how the water mist is currently approved to the market is by extensive testing.

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<v Wojciech Węgrzyński>Pretty much that's my observation of the market, compared, for example, with smoke control.

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<v Wojciech Węgrzyński>In smoke control we have barely anything like that.

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<v Wojciech Węgrzyński>In smoke control we have barely anything like that.

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<v Wojciech Węgrzyński>In smoke control it's all you know mathematical equations that tell you how much smoke you produce.

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<v Wojciech Węgrzyński>Or CFD modeling, where you just simulate your smoke control system and you see if it works In the water mist.

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<v Wojciech Węgrzyński>It's all based on experimental insight.

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<v Wojciech Węgrzyński>Is there also any particular reason why the industry is so uh, I wouldn't like I want to use the word obsessed, but it's not the correct word perhaps why it's so based on on physical testing?

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<v Wojciech Węgrzyński>And does, in such a world of such strong emphasis on physical testing, does performance based design or cfdD even have place for?

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<v Max Lakkonen>I think your question is, let's say, two, Paul.

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<v Max Lakkonen>One is related to the experimental testing.

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<v Max Lakkonen>Another one is then to the new, let's say, design methods, 3D and simulation.

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<v Wojciech Węgrzyński>Yeah, let's chop it into two questions.

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<v Wojciech Węgrzyński>I mean, if we are looking, to the history of water mist.

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<v Max Lakkonen>I mean now I'm starting very far, so something like 35 years ago.

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<v Max Lakkonen>That was when the commercial use of water mist started after the fire in Scandinavia and star cruise liner Very, very bad fire.

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<v Max Lakkonen>And obviously then water mist started to conquer the marine business and nowadays, for example, cruise liners, they are having almost 100% market share and also the engine ships or the machinery rooms.

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<v Max Lakkonen>I mean they are having very, very high portion of this system.

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<v Max Lakkonen>So that's where it all started.

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<v Max Lakkonen>But since day one, watermistist was considered something new and it was careful.

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<v Max Lakkonen>I mean, everybody had to be careful because higher pressures and new approach and then a lot of experimental tests were required.

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<v Max Lakkonen>Therefore, basically every new application requires some tests and also because the technologies are different.

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<v Max Lakkonen>You know, in different uh makes they are based on performance base design.

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<v Max Lakkonen>They are not, let's say, prescriptive than that sprinklers are, for example, that you do a certain application rate and everything is good.

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<v Max Lakkonen>But obviously two companies might go to a very same protection objective or the performance with the two different nozzle spacing, two different floor rates, two different nozzle types, and that's been the reason why there has been so much testing in the past.

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<v Max Lakkonen>But nowadays the situation is good.

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<v Max Lakkonen>There are many test standards and there are many companies and they are now covering a really huge number of approvals to various different kinds of applications.

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<v Wojciech Węgrzyński>You've mentioned different nozzle types and I assume one company could use different pressure, different flow rates etc.

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<v Wojciech Węgrzyński>So these things are really that sensitive.

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<v Wojciech Węgrzyński>You really have to fine tune that in an experimental setting.

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<v Wojciech Węgrzyński>I mean, I know you are doing that because I've seen that firsthand.

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<v Wojciech Węgrzyński>But I'm like really curious, like let me rephrase the question Is there any way you could like talk about generic water mist, you know, and generic flow rates or generic pressures and just don't go through this expensive, you know pathway of testing?

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<v Max Lakkonen>No, no, unfortunately that's not the case, and obviously all the companies.

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<v Max Lakkonen>They have really tried to innovate and find, let's say, technically and commercially, the best solutions.

00:18:15.612 --> 00:18:22.251
<v Max Lakkonen>It's a different approach but on the other hand it's a bit of the PPD-orientated thing.

00:18:22.251 --> 00:18:38.991
<v Max Lakkonen>But coming now to your technology design, so the objective was given and it was given by the standardization bodies, by the authorities, that, okay, this is the test you need to do, this is accepted criteria, no matter how you get there.

00:18:38.991 --> 00:19:02.604
<v Max Lakkonen>And after you have passed the test, you have to do that, the component test, and after that you have the approval to install the system, so kind of like pbd, but powered by experimental research for a very narrow spectrum of use, right it's a narrow in that sense that you, for different risk category, you have to do on fire test series following the standard.

00:19:02.624 --> 00:19:20.228
<v Max Lakkonen>so obviously if you have to do on-fire test series following the standard, so obviously if you have a building, so in the building you might have an office space or accommodation, you might have a car park, you might have some electric room and obviously cable tunnel.

00:19:20.700 --> 00:19:38.970
<v Wojciech Węgrzyński>So all these they are having on their standards and at the companies they have to invest to get an approval for those, and and this even goes beyond, because it's not just office to car park it's like one system for office with three meter tall ceiling, one for correct with five meter tall ceiling, right correct I mean obviously.

00:19:39.029 --> 00:19:46.140
<v Max Lakkonen>then it might be that if you're doing with a higher than you are, normally you're okay for lower installation, but if you're doing with a higher, then normally you're okay for lower installation.

00:19:46.140 --> 00:19:56.240
<v Max Lakkonen>But if you're doing it doesn't work the other way around and obviously if you're having the lower test set up, then obviously you can save a lot of water.

00:19:56.941 --> 00:20:05.099
<v Wojciech Węgrzyński>So, based on that, there's a fire safety engineer, like, let's say, someone just finished their fire safety engineering course at the university.

00:20:05.099 --> 00:20:08.132
<v Wojciech Węgrzyński>Just there's basically no way they can figure it out.

00:20:08.132 --> 00:20:17.352
<v Wojciech Węgrzyński>They need a water mist company to help them find the correct nozzle, spacing, pressure, flow rates, etc.

00:20:17.352 --> 00:20:28.169
<v Wojciech Węgrzyński>Right, because, uh, it's so specific I I find it difficult to to give like a you know, hire a new person to my lab and tell them okay, from tomorrow you're designing Watermist.

00:20:28.169 --> 00:20:30.926
<v Wojciech Węgrzyński>Here's like five books you have to read and you'll be good.

00:20:30.926 --> 00:20:32.651
<v Wojciech Węgrzyński>That won't be enough.

00:20:32.651 --> 00:20:34.085
<v Wojciech Węgrzyński>You need experience from lab, right?

00:20:34.567 --> 00:20:37.859
<v Max Lakkonen>No, no, no, no, I think it's again another misconception.

00:20:37.859 --> 00:20:43.788
<v Max Lakkonen>So I mean you can look even some of the standards or standardization organization.

00:20:43.788 --> 00:20:54.574
<v Max Lakkonen>They show, let's say, which companies have approved certain applications and obviously from there you get the main information to design the system.

00:20:54.574 --> 00:20:56.768
<v Max Lakkonen>But definitely it's different.

00:20:56.768 --> 00:21:02.413
<v Max Lakkonen>It's not that you would for every building that you would need to do a validation or fire test.

00:21:02.413 --> 00:21:09.726
<v Max Lakkonen>I mean it's just that these companies they have done for different number of applications that they are good, regardless of what is the building.

00:21:09.726 --> 00:21:25.788
<v Max Lakkonen>But transferring the information then from the companies, from the industry to the fire engineer, that's the hurdle to make the link, and obviously IWMA is also playing there between trying to spread the knowledge.

00:21:26.805 --> 00:21:37.085
<v Wojciech Węgrzyński>Okay, that's much better, because for a second I was worried that this is so specific to the solution that there would be no way that just a fire engineer could work.

00:21:37.085 --> 00:21:49.736
<v Wojciech Węgrzyński>But yeah, if you're directed towards the suppliers and suppliers are openly sharing their applications and their protocols and the results of their tests, then probably you can work it out.

00:21:49.736 --> 00:21:58.145
<v Wojciech Węgrzyński>Previously you've also mentioned there are different types of water mist that would result on with different water distributions.

00:21:58.145 --> 00:22:00.827
<v Wojciech Węgrzyński>I know there's low pressure water mist.

00:22:00.827 --> 00:22:02.169
<v Wojciech Węgrzyński>I know there's high pressure water mist.

00:22:02.169 --> 00:22:09.575
<v Wojciech Węgrzyński>Would you like to comment on the types of water mist and perhaps how big of a difference does it really make that you have?

00:22:09.615 --> 00:22:13.057
<v Wojciech Węgrzyński>different operating pressures, because that seems to distinguish them.

00:22:13.698 --> 00:22:15.818
<v Max Lakkonen>Operating pressures because that seems to distinguish them.

00:22:15.818 --> 00:22:22.976
<v Max Lakkonen>If I would say, as a rule of thumb, the droplets sizes or small droplets, you can do both with the high or low pressure.

00:22:22.976 --> 00:22:49.390
<v Max Lakkonen>But if you want to combine small droplet sizes together with the momentum, so having the smaller droplets and shooting them into the protective volume with the high momentum, that requires energy, that requires higher pressure and some of the applications you really gain of having both small droplets and then filling very effectively the volume.

00:22:49.390 --> 00:22:54.511
<v Max Lakkonen>So that's probably one of the fundamental changes.

00:22:54.511 --> 00:23:02.388
<v Max Lakkonen>And obviously then it correlates to the flow rate that typically, because of this effect, higher pressures they are having lower flow rates.

00:23:02.388 --> 00:23:17.073
<v Max Lakkonen>But if we are looking to the standardized risks, so there is a test protocol placed by the standards and obviously you can pass this test with low pressure or high pressure.

00:23:17.073 --> 00:23:21.229
<v Max Lakkonen>It's then up to the manufacturer what they're going to do.

00:23:22.704 --> 00:23:24.357
<v Wojciech Węgrzyński>I think we've covered a lot of fundamentals.

00:23:24.357 --> 00:23:29.509
<v Wojciech Węgrzyński>Perhaps it's time to start moving to the challenges with CFD modeling.

00:23:29.509 --> 00:23:38.692
<v Wojciech Węgrzyński>The second part of my question where do you see modeling water mists as a part of the design?

00:23:38.692 --> 00:23:50.453
<v Wojciech Węgrzyński>I mean, you obviously can't replace the protocol with CFD itself, but where would it be useful for you as an engineer, to put water mists into your modeling?

00:23:51.079 --> 00:23:57.874
<v Max Lakkonen>Well, obviously I'd say modeling has been typically used in combination with this system.

00:23:57.874 --> 00:24:08.265
<v Max Lakkonen>Also, it's frankly decided if there would be a fire test to be carried out, and obviously fire testing is not very cheap.

00:24:08.265 --> 00:24:17.335
<v Max Lakkonen>Pre-studies by modeling will save a lot from manufacturers, let's say time and cost.

00:24:17.335 --> 00:24:20.183
<v Max Lakkonen>On the experimental side.

00:24:20.183 --> 00:24:23.173
<v Max Lakkonen>It would apply also to any other technology.

00:24:23.173 --> 00:24:27.501
<v Max Lakkonen>So that's kind of virtual pre-testing where it's been used.

00:24:27.501 --> 00:24:39.895
<v Max Lakkonen>And then obviously then we are not there that we would be able to fully justify the designs of any kind just based on pure CFD.

00:24:39.895 --> 00:24:43.028
<v Max Lakkonen>So that's still difficult.

00:24:43.028 --> 00:25:06.300
<v Max Lakkonen>But again, if we are having good experimental data, so then we can use in the kind of post-processing assessing that, for example that compared to the file test, if the geometry would have different dimensions, so probably we can mitigate this based on on the cfd works.

00:25:06.300 --> 00:25:09.346
<v Max Lakkonen>Or we will have a different ventilation conditions.

00:25:09.346 --> 00:25:13.134
<v Max Lakkonen>So again we can use cfd to assess the influences.

00:25:13.134 --> 00:25:19.250
<v Max Lakkonen>Or we want to studyD to assess the influences, or we want to study the effect to the structure, or you name it.

00:25:19.661 --> 00:26:03.824
<v Wojciech Węgrzyński>So you mean more, like in structural fire resistance, we had this extrapolation possibilities that were called the EXAPs extended application and basically it meant that if you run tests on your furnace for long enough, you can extend the height of the sample to a little higher one, based on the fact that you have extended your tests or objective results of an experiment into slightly different geometry, slightly different ventilation conditions, by simulating the original experiment and the extension and then working out like what's the difference?

00:26:03.824 --> 00:26:04.987
<v Wojciech Węgrzyński>Like is it still applicable?

00:26:04.987 --> 00:26:05.588
<v Wojciech Węgrzyński>Something like that?

00:26:05.950 --> 00:26:07.121
<v Max Lakkonen>yeah correct, correct.

00:26:07.121 --> 00:26:19.395
<v Max Lakkonen>So typically then is is then utilizing, let's say, or doing the validation with the experimental test, and then moving this scenario into the real geometry.

00:26:20.240 --> 00:26:23.900
<v Wojciech Węgrzyński>Yeah, being blessed with collaboration between ITB and the Baltic Fire Lab.

00:26:23.900 --> 00:26:31.013
<v Wojciech Węgrzyński>This is also something that we see an immense future in studying and learning how to do properly.

00:26:31.013 --> 00:26:34.041
<v Wojciech Węgrzyński>And how about building applications Like?

00:26:34.041 --> 00:26:43.025
<v Wojciech Węgrzyński>I won't break any NDAs if I tell you I've been challenged to those simulations a few times in my life and then a few times we had to do them because the client really needed them.

00:26:44.126 --> 00:27:10.251
<v Wojciech Węgrzyński>What I have in mind is simulating what it means in an office layout, to prove that it works, or to give a proof that it doesn't like destroy the operations of ventilation or some other, but basically as a proof that in the building setting it's going to operate how to even say it nicely To give a bunch of nice colorful pictures that it works correctly.

00:27:10.251 --> 00:27:14.069
<v Wojciech Węgrzyński>What's your take on those aspects of PVD?

00:27:14.069 --> 00:27:19.904
<v Wojciech Węgrzyński>Because, if I may, uh, one more sentence that that's what we do with smoke control.

00:27:19.904 --> 00:27:26.107
<v Wojciech Węgrzyński>For smoke control we don't have protocols, we don't have extensive experimental proof for any different occupancy.

00:27:26.107 --> 00:27:32.425
<v Wojciech Węgrzyński>We just do the system as it is on the building and based on that we make conclusions does it work or not?

00:27:33.288 --> 00:27:36.973
<v Max Lakkonen>yeah, and I I think there is a fundamental difference.

00:27:36.973 --> 00:27:54.906
<v Max Lakkonen>When we're talking about smoke control, so then we are not really influencing the fire, and obviously when we are having water being involved, so typically that influences the pure loses process and and obviously it's interacting with the fire itself.

00:27:54.906 --> 00:27:58.294
<v Max Lakkonen>So already the equations are way more difficult.

00:27:58.294 --> 00:28:11.811
<v Max Lakkonen>So, yes, we also, we are doing a lot of simulation related to smoke control in buildings, in tunnels, in metro stations, and it's standardized there.

00:28:11.811 --> 00:28:21.210
<v Max Lakkonen>But if we are looking to the office building, so typically in the office building I mean office areas, it's typical or ordinary areas at one.

00:28:21.700 --> 00:28:31.750
<v Max Lakkonen>Normally there is not even question whether the MIS system or shrinker, with the regular spacing five millimeters per minute, whether they would be accepted or not.

00:28:31.750 --> 00:28:40.049
<v Max Lakkonen>Typically it has to do then, like you said, with the certain ventilation condition that some people will come with a question.

00:28:40.049 --> 00:28:44.327
<v Max Lakkonen>They probably don't do a fixed question for sprinklers because they think it's a standard.

00:28:44.327 --> 00:28:55.430
<v Max Lakkonen>Very few people actually remember where this five millimeters per minute actually came from and probably that time the furniture was different and the building materials were also different.

00:28:55.430 --> 00:29:00.428
<v Max Lakkonen>But anyway, that's a side topic, but for these special cases.

00:29:00.428 --> 00:29:12.468
<v Max Lakkonen>So there's something with the ventilation or with the atrium or whatsoever, and it has to do a lot with the experience of the people using the CFDS.

00:29:14.061 --> 00:29:15.888
<v Wojciech Węgrzyński>And I assume, validation well, I assume.

00:29:15.888 --> 00:29:19.451
<v Wojciech Węgrzyński>I know validation for those cases is very, very challenging.

00:29:19.451 --> 00:29:32.660
<v Wojciech Węgrzyński>When we were visiting the Baltic Fire Lab a few weeks ago on the summer school, bogdan was explaining water mist and he mentioned that the water mist experiments are compared to sprinkler experiments.

00:29:32.660 --> 00:29:38.865
<v Wojciech Węgrzyński>And I've asked him are sprinkler experiments expected to be compared with water mist as reference?

00:29:38.865 --> 00:29:41.106
<v Wojciech Węgrzyński>And he made a very sad face.

00:29:41.106 --> 00:29:42.564
<v Wojciech Węgrzyński>So it's kind of weird.

00:29:42.584 --> 00:29:49.819
<v Wojciech Węgrzyński>You know that one technology is given completely different scrutiny as another, even though we are in the same fire safety market.

00:29:49.819 --> 00:30:01.121
<v Wojciech Węgrzyński>And the performance of that, and especially if you compare it to the smoke control, where you have literally no experimental proof and you base everything on on your engineering judgment fueled by numerical modeling.

00:30:01.121 --> 00:30:11.968
<v Wojciech Węgrzyński>You you've said something very important explaining me that that case is that you will have difficulties capturing the influence between the mist and the fire.

00:30:11.968 --> 00:30:22.869
<v Wojciech Węgrzyński>So what if you go another simplified way just reduce the fire size and just model the cooling effects to what the mist has on the smoke and air?

00:30:22.869 --> 00:30:27.507
<v Wojciech Węgrzyński>Would that give you anything, any knowledge you could work with?

00:30:27.507 --> 00:30:30.384
<v Wojciech Węgrzyński>Or it's just too generic to?

00:30:30.443 --> 00:30:31.950
<v Wojciech Węgrzyński>find it useful in engineering.

00:30:32.200 --> 00:30:48.327
<v Max Lakkonen>Yeah, I think that's the, the, the common way, that's a common practice because we see that the cfd is not major enough to to go 100 modeling, including the combustion in combination with mist.

00:30:48.327 --> 00:30:55.613
<v Max Lakkonen>So then the the other approach is then using the semi-emperial models, which we actually strongly suggest.

00:30:55.613 --> 00:31:17.392
<v Max Lakkonen>So we are taking the design fire curve based on the experimental tests, that we use this, and then we can model that how water miss is influenced, the outcome, the output of the fire, how it's cooling and how is, for example, shielding, what are the radiation level or heat transfer to the structure?

00:31:17.392 --> 00:31:27.031
<v Max Lakkonen>There the question is that, if you don't have the experimental data, so then the question is that where do you cut the design curve?

00:31:27.031 --> 00:31:39.332
<v Max Lakkonen>So is that when the first sprinkler will activate, you then take the flat If you have the data from the free burn test, and that's where there is, let's say, normally the main discussion.

00:31:40.039 --> 00:31:44.632
<v Wojciech Węgrzyński>So one approach would be just to base it on the nearest protocol you have.

00:31:44.632 --> 00:31:53.689
<v Wojciech Węgrzyński>Let's say you're having an office, so there is this office protocol with these desks and items on the desk, fire, shielded from the water, et cetera, et cetera.

00:31:53.689 --> 00:31:59.807
<v Wojciech Węgrzyński>If you have heat release rate from experiment like that with water mist, you just put that into CFD.

00:31:59.807 --> 00:32:19.846
<v Wojciech Węgrzyński>And if you don't have an access to a good enough experiment with heat release rate measurements, which are not that common actually, you would basically go alpha T squared growth applicable for a specific design situation and then, just based on activation, figure out a reasonable time to cut off the curve and flatten it.

00:32:19.846 --> 00:32:20.347
<v Wojciech Węgrzyński>Do I?

00:32:20.407 --> 00:32:21.231
<v Max Lakkonen>understand correctly.

00:32:21.231 --> 00:32:23.147
<v Max Lakkonen>Yeah, that would be.

00:32:23.147 --> 00:32:30.005
<v Max Lakkonen>Let's say, they're very simplified, I think I rather always would prefer the real measurements of the fuel pack.

00:32:30.759 --> 00:32:32.625
<v Wojciech Węgrzyński>As in referring to experiment.

00:32:33.027 --> 00:32:33.869
<v Max Lakkonen>Yeah correct.

00:32:35.340 --> 00:32:45.173
<v Max Lakkonen>And then obviously, depending how conservative the approach you want to do, if you have any crypt, that will be the influence of mist, then to the fire itself.

00:32:45.173 --> 00:32:56.133
<v Max Lakkonen>I mean, you can do the most conservative, but you don't give any impact, you let it burn as a maximum and then you see what will be the outcome.

00:32:56.133 --> 00:33:03.054
<v Max Lakkonen>And then obviously there are also some tests where there is a data how it's influencing.

00:33:03.054 --> 00:33:07.071
<v Max Lakkonen>But then obviously this has to do also a lot with the manufacturers.

00:33:07.071 --> 00:33:11.925
<v Max Lakkonen>They process this data, so you have to be close to them.

00:33:13.461 --> 00:33:25.708
<v Wojciech Węgrzyński>One that comes to my mind is, if I was doing a car park, I would probably just leave, you know, the car park kit release rate as it is from my normal generic design fire and just model the cooling effects.

00:33:25.708 --> 00:33:37.127
<v Wojciech Węgrzyński>I mean that would probably end in some like worst case scenario where you fail to influence the fire inside the vehicle, but she got the cooling effects which.

00:33:37.127 --> 00:33:40.386
<v Wojciech Węgrzyński>Because, like, what question are we answering with this?

00:33:40.386 --> 00:33:59.375
<v Wojciech Węgrzyński>Like if we cut down the case where we want to showcase a colorful pictures to the firefighter who has to say whether the building is approved or not, if we just cut this use of cfd, which obviously would be like one third or maybe half of the market and you want to study something, you want to understand, what question can you get?

00:33:59.375 --> 00:34:11.871
<v Wojciech Węgrzyński>And the idea that comes to my mind is that, okay, I'm going to have different temperatures, my smoke is going to have different buoyancy, that most likely influences my flows and layers and everything right.

00:34:12.400 --> 00:34:14.568
<v Max Lakkonen>But let me throw the question back to you.

00:34:14.568 --> 00:34:18.525
<v Max Lakkonen>If it would be a traditional Spreepio, how would you do that?

00:34:18.925 --> 00:34:24.226
<v Wojciech Węgrzyński>Huh, yeah, I would probably in this case do the same If it's a car park.

00:34:24.226 --> 00:34:31.224
<v Wojciech Węgrzyński>Car park is for me a specific scenario in which the vehicles are generally meant to not let water in.

00:34:31.224 --> 00:34:32.809
<v Wojciech Węgrzyński>You know Exactly.

00:34:33.380 --> 00:34:34.083
<v Max Lakkonen>That's the point.

00:34:34.083 --> 00:34:41.795
<v Max Lakkonen>Even you know, know, when you're doing the oh it's fun test arrangement, you you activate or you start the fire under the table.

00:34:41.795 --> 00:34:54.027
<v Max Lakkonen>Yeah, so obviously sprinkler will not do anything until the fire will go above the table and ignites the things because there's no entrance for water influencing theluenced fire.

00:34:54.027 --> 00:34:58.181
<v Max Lakkonen>So this very same question remains regardless.

00:34:58.181 --> 00:35:02.092
<v Max Lakkonen>What is then the technology you are utilizing?

00:35:02.742 --> 00:35:19.233
<v Wojciech Węgrzyński>But if you ask me the question what I would do if I was simulating a high-rec storage building, then I would most likely try to estimate the time to trigger the sprinklers in between four settings.

00:35:19.233 --> 00:35:29.362
<v Wojciech Węgrzyński>So I have the furthest distance to my sprinklers and I would apply some delay because I assume that it takes time to build up the pressure in the pipes.

00:35:29.362 --> 00:35:35.469
<v Wojciech Węgrzyński>You know, trigger the jockey pump, then trigger the main pump and also before all four hats start up.

00:35:35.469 --> 00:35:40.532
<v Wojciech Węgrzyński>So let's say I would have the initial trigger in 100 seconds.

00:35:40.532 --> 00:35:53.253
<v Wojciech Węgrzyński>I would probably add like at least 60 seconds to that and then I would cut my alpha T-square curve in that case, or maybe alpha T-thirds curve if I was doing design for Singapore.

00:35:53.253 --> 00:35:55.547
<v Wojciech Węgrzyński>But yeah, I would probably do that.

00:35:55.547 --> 00:35:58.489
<v Wojciech Węgrzyński>I'm not sure how valid or common that would be.

00:35:59.139 --> 00:36:02.063
<v Max Lakkonen>But obviously there you need to study a lot that.

00:36:02.063 --> 00:36:03.172
<v Max Lakkonen>What is your field?

00:36:03.172 --> 00:36:04.099
<v Max Lakkonen>Absolutely.

00:36:04.420 --> 00:36:06.168
<v Max Lakkonen>And whether it's the outer surface.

00:36:06.168 --> 00:36:17.927
<v Max Lakkonen>We are actually doing the work or we've been doing actually for the battery storages, similar to the high rack storages or multiple shelves, but anyway, that's a different topic.

00:36:17.927 --> 00:36:31.226
<v Max Lakkonen>But we actually, I mean we started with the model, the main input data which is the influence to the heat release rate, and I mean over this whole CFD water mist combination.

00:36:31.226 --> 00:36:46.474
<v Max Lakkonen>We actually published as an IWMA position paper last week where we as a society, we wanted to give a kind of best practice how to tackle these topics.

00:36:47.440 --> 00:36:54.014
<v Wojciech Węgrzyński>And, on contrary, because it's this practice that really triggers me, annoys me very, very badly.

00:36:54.014 --> 00:36:56.467
<v Wojciech Węgrzyński>And it's your society doing that.

00:36:56.467 --> 00:37:03.300
<v Wojciech Węgrzyński>No, not you personally, perhaps, but no, you have those guys who do tunnels and they would burn the town, the fire.

00:37:03.300 --> 00:37:07.510
<v Wojciech Węgrzyński>Without water mist in the tunnel, the fire would reach like 200 megawatts.

00:37:07.510 --> 00:37:10.304
<v Wojciech Węgrzyński>Then they would run the same test with water mist.

00:37:10.304 --> 00:37:13.842
<v Wojciech Węgrzyński>It reaches whatever 30 megawatts, 50 megawatts, whatever the number.

00:37:14.422 --> 00:37:21.806
<v Wojciech Węgrzyński>And then, uh, they give an impression that the water mist is capable of fighting 200 megawatt fire, and for me it's like such a trigger.

00:37:21.806 --> 00:37:26.711
<v Wojciech Węgrzyński>I mean, what water mist does is preventing the 200 megawatt fire from ever happening.

00:37:26.711 --> 00:37:31.170
<v Wojciech Węgrzyński>But when it is 200 megawatts, there's not much you can do.

00:37:31.170 --> 00:37:33.889
<v Wojciech Węgrzyński>And why I'm annoyed?

00:37:33.889 --> 00:37:35.414
<v Wojciech Węgrzyński>There's not much you can do.

00:37:35.414 --> 00:37:36.920
<v Wojciech Węgrzyński>And why I'm annoyed?

00:37:36.920 --> 00:37:43.188
<v Wojciech Węgrzyński>Because we've been forced to run simulations for cases where someone wanted 200 megawatt fire and the water mist at the same time.

00:37:43.188 --> 00:37:44.525
<v Wojciech Węgrzyński>And prove me it works.

00:37:44.525 --> 00:37:53.106
<v Wojciech Węgrzyński>And I'm like it's just like you're asking me for a Star Trek and Star Wars universes merged together in one space.

00:37:53.106 --> 00:37:54.525
<v Wojciech Węgrzyński>It just will not work.

00:37:54.525 --> 00:37:55.922
<v Wojciech Węgrzyński>It's not how it works.

00:37:55.922 --> 00:37:56.724
<v Wojciech Węgrzyński>It triggers me a lot.

00:37:58.269 --> 00:38:09.887
<v Max Lakkonen>I think I have to tell you one thing that we are probably the first one who have actually done the test 200 megawatt digger law and then activated the MIS system.

00:38:09.887 --> 00:38:12.568
<v Max Lakkonen>I'm not sure if you were aware of that.

00:38:12.568 --> 00:38:19.313
<v Max Lakkonen>There is one occasion when it was done and it was for the channel tunnel.

00:38:19.697 --> 00:38:19.838
<v Wojciech Węgrzyński>Okay.

00:38:21.021 --> 00:38:24.590
<v Max Lakkonen>And it was 2,000 pallets and I don't know how many pools.

00:38:24.590 --> 00:38:31.570
<v Max Lakkonen>We did it, but it's a rail tunnel with a piston effect, so we also modeled the ventilation conditions.

00:38:31.570 --> 00:38:46.655
<v Max Lakkonen>But there is one occasion where it's been done and very, very scary Something like I don't even remember it must be 15 years ago, but it had nothing to do with the road tunnels though, so that's it?

00:38:46.675 --> 00:38:52.079
<v Wojciech Węgrzyński>No, that's cool, but what happened when you released water into 200 megawatt fire?

00:38:52.079 --> 00:38:56.952
<v Wojciech Węgrzyński>Did it still give you significant reduction in temperatures?

00:38:57.942 --> 00:38:58.804
<v Max Lakkonen>Absolutely.

00:38:58.804 --> 00:39:06.521
<v Max Lakkonen>We obviously took it control quite quickly and obviously it's also a combination with the ventilation.

00:39:06.521 --> 00:39:10.744
<v Max Lakkonen>So there also, the ventilation is asked to play an important role.

00:39:10.744 --> 00:39:28.481
<v Max Lakkonen>And, having said that, our intention was not to go to 200 megawatt, the trigger imposed was 150 megawatts, but the safety valve of the pump unit popped and we had to restart the pump and then very, very nervous people started to be around and then we started to lose.

00:39:28.481 --> 00:39:30.469
<v Max Lakkonen>Camera here, camera there.

00:39:30.510 --> 00:39:32.318
<v Max Lakkonen>Nobody was allowed inside the tunnel.

00:39:32.318 --> 00:39:44.128
<v Max Lakkonen>Yeah, I can imagine that and you could see that how it was in TSD, how the tunnel was leaking also between the joints, but anyways, everything went fine.

00:39:44.128 --> 00:39:46.646
<v Max Lakkonen>But obviously you don't want to.

00:39:46.646 --> 00:39:58.487
<v Max Lakkonen>If you are planning a road tunnel, I mean in the channel tunnel, the train can travel quite a long time having the trucks burning on board, so that's why there's a lot of time.

00:39:58.487 --> 00:40:03.382
<v Max Lakkonen>But in the road terminal you obviously want to activate as quick as possible.

00:40:03.382 --> 00:40:10.025
<v Max Lakkonen>If you go to that level of the fires, I mean most of the technical equipment is already destroyed.

00:40:10.025 --> 00:40:13.228
<v Max Lakkonen>So I mean it doesn't make sense.

00:40:14.682 --> 00:40:23.769
<v Wojciech Węgrzyński>Well, that's a very brutal, yet such such a important uh observation that the technical systems will be already destroyed.

00:40:23.769 --> 00:40:47.945
<v Wojciech Węgrzyński>I I don't think people appreciate logic enough in in the fire community and uh, for me that that's, that's a very logical conclusions that if you don't have your pipes and nozzles there, or they bend it or they fell down from the ceiling which is most likely when you have a fire of 200 megawatts that there's not much they can do to reduce the size, perhaps reduce the.

00:40:47.945 --> 00:40:52.820
<v Wojciech Węgrzyński>Of course they would reduce the temperatures a little bit, but yeah, it's going to be challenging.

00:40:52.820 --> 00:40:58.829
<v Wojciech Węgrzyński>You must have used a lot of water in that channel fire test to get that piece under control.

00:41:00.643 --> 00:41:16.646
<v Max Lakkonen>Yeah, it was probably more than in the road channel, but it was not, let's say, the huge amount and obviously for many kinds of fires, obviously bigger the fire is, more evaporation there is, better the system will be Okay.

00:41:16.786 --> 00:41:27.041
<v Wojciech Węgrzyński>So we've covered a bit the suppressing the fire tricks and tricks of the trade, how you can deal with that.

00:41:27.041 --> 00:41:30.467
<v Wojciech Węgrzyński>I assume modeling the true suppression at the fuel.

00:41:30.467 --> 00:41:37.701
<v Wojciech Węgrzyński>This is only applicable to, maybe, pre burn studies.

00:41:37.701 --> 00:41:49.215
<v Wojciech Węgrzyński>I know guys at FM are really good at doing stuff like that, like modeling before they burn, and perhaps I'll get someone from FM to talk on that one day.

00:41:49.215 --> 00:41:52.184
<v Wojciech Węgrzyński>How about the gas phase?

00:41:52.184 --> 00:41:55.846
<v Wojciech Węgrzyński>So the phenomena that are happening in gas phase, for me two are important.

00:41:55.846 --> 00:41:57.527
<v Wojciech Węgrzyński>One is three are important.

00:41:57.527 --> 00:42:01.610
<v Wojciech Węgrzyński>One is evaporation, that is, how much heat is taken out in the gas phase.

00:42:01.610 --> 00:42:08.969
<v Wojciech Węgrzyński>The second is the change in oxygen concentration with the evaporation, which you've mentioned, important for the pool fires.

00:42:08.969 --> 00:42:26.289
<v Wojciech Węgrzyński>And third one, uh, for me an important, the uh, water induced airflow, like like the momentum pushed onto the air and how it changes, because for me it's important to consider the smoke layer disruption, for example.

00:42:26.289 --> 00:42:32.809
<v Wojciech Węgrzyński>So how confident are you with our capability of modeling those phenomena with our CFD packages?

00:42:32.809 --> 00:42:36.726
<v Wojciech Węgrzyński>And perhaps there's also tricks of the trade that people should be aware of.

00:42:38.960 --> 00:42:39.846
<v Max Lakkonen>That's a difficult one.

00:42:39.846 --> 00:42:45.492
<v Max Lakkonen>So I'm looking more from the perspective of, let's say, application.

00:42:45.492 --> 00:42:50.811
<v Max Lakkonen>So I mean, what is then practical to be used in real life?

00:42:50.811 --> 00:43:02.668
<v Max Lakkonen>And before going to that we could look then okay, I mean, if we are looking, looking these very same topics from the academic perspective, so I think there is a lot to be improved.

00:43:02.668 --> 00:43:04.510
<v Max Lakkonen>So I I think these are.

00:43:05.172 --> 00:43:23.043
<v Max Lakkonen>If we would then combine these, these three things also with the droplets and the interaction of droplets together, droplets together, these would be, I mean, big stickly.

00:43:23.043 --> 00:43:35.329
<v Max Lakkonen>Then further, but if we are looking from the, the technology as it is I'm now referring cfd technology as it is so what I've seen is that I think we can predict with a fairly good confidence the, the influences when it comes to the cooling.

00:43:35.329 --> 00:43:43.710
<v Max Lakkonen>Normally we are not so much of interest about the, the air or, let's say, the oxygen, okay, itself.

00:43:43.710 --> 00:43:50.027
<v Max Lakkonen>I think that that's more the academic research, but we are more interested that what will happen for the fire.

00:43:50.027 --> 00:44:01.054
<v Max Lakkonen>So, and obviously that's more the, the question and the, the interaction between the, for example, with the stratification, which truly is of your interest.

00:44:01.054 --> 00:44:09.871
<v Max Lakkonen>So I think that's also quite well known and there's a lot of data, also from experimental data, from the test.

00:44:11.240 --> 00:44:24.668
<v Wojciech Węgrzyński>We're also looking for effects in relation for tunnels, for example, how big resistance the water mist cloud brings to the tunnel as a factor in my pressure equation that drives the design of my smoke control.

00:44:24.668 --> 00:44:32.731
<v Wojciech Węgrzyński>So there are more factors, but I'm also fairly confident in the ability of modern CFD packages to capture this phenomenon and all that.

00:44:32.731 --> 00:44:37.362
<v Wojciech Węgrzyński>One more that we didn't touch modeling the water mist release.

00:44:37.362 --> 00:44:48.436
<v Wojciech Węgrzyński>That I find really challenging, because if you want to model water mist it doesn't magically appear in your model you have to spray it from something right.

00:44:48.436 --> 00:45:08.532
<v Wojciech Węgrzyński>And to model a real nozzle and model the physics that happens at the nozzle itself, that's like nozzle itself, that's a PhD, like that's a simulation on its own right, but I don't want to do a PhD every time I sell my CFD to someone.

00:45:09.001 --> 00:45:10.246
<v Wojciech Węgrzyński>I need a reliable model.

00:45:10.246 --> 00:45:12.742
<v Wojciech Węgrzyński>So there are simplifications In FDS.

00:45:12.742 --> 00:45:17.965
<v Wojciech Węgrzyński>There is this simple model you put some angles, you put the pressures, you put the flows and you get some outcome.

00:45:17.965 --> 00:45:20.030
<v Wojciech Węgrzyński>How you feel about that?

00:45:20.030 --> 00:45:22.516
<v Wojciech Węgrzyński>Where are we heading with this?

00:45:22.516 --> 00:45:31.043
<v Wojciech Węgrzyński>Is it going to be more simple, like I'll get the catalog of nozzles from manufacturer one, two, three, I'll just put them in my model and they will work?

00:45:31.043 --> 00:45:39.371
<v Wojciech Węgrzyński>Or there is a lot of stuff that I should pay attention to when I try to model that no, I don't think so that it would be so complicated.

00:45:39.500 --> 00:45:49.242
<v Max Lakkonen>I mean we have done multiple times multiple nozzles and no BHD, no BHDs yet Again.

00:45:49.242 --> 00:45:57.391
<v Max Lakkonen>I mean, obviously you are doing the comparison for sprinklers and sprinklers are default values basically.

00:45:57.391 --> 00:46:04.630
<v Max Lakkonen>So if you would have more complicated sprinkler head as well, I mean you would need to do exactly the same exercise.

00:46:04.630 --> 00:46:17.581
<v Max Lakkonen>But typically the mist nozzles, they are having the optimum performance, they are having the multiple orifices, so multiple kind of jets per head, and this is like you said.

00:46:17.581 --> 00:46:28.855
<v Max Lakkonen>You have the model, the geometry, you need to know the droplet distribution and then you need to know the velocity and that's pretty much all what you need to do.

00:46:28.855 --> 00:46:44.414
<v Max Lakkonen>So we've been quite at least satisfied with the way we have done and we have done also comparison just with the application rate, experiential versus CFD, and with the results.

00:46:45.260 --> 00:47:03.503
<v Wojciech Węgrzyński>Okay, and for the final, maybe from your experience modeling different types of water mist systems, any particular case which you recollect that gave you the most trouble, or issues like the most challenging one you've done, I mean, I think they all.

00:47:03.523 --> 00:47:06.672
<v Max Lakkonen>They have had challenges in a certain ways.

00:47:06.672 --> 00:47:16.632
<v Max Lakkonen>I mean, often it's a combination that, okay, we are having very big volume and then obviously we have to be using very small cell sizes.

00:47:16.632 --> 00:47:25.847
<v Max Lakkonen>I mean it can do with that kind of difficulties, or it have to do with the difficulties that we don't have a good validation data.

00:47:25.847 --> 00:47:43.333
<v Max Lakkonen>Then we have to do much more analytical work, we have to look to some application which being close, or it might be also that we have to think about the interaction between water and the fire itself and how it's going to influence.

00:47:43.333 --> 00:47:47.672
<v Max Lakkonen>We don't want to go with the overly conservative approach.

00:47:47.672 --> 00:48:06.532
<v Max Lakkonen>So there are give a kind of guidance that what is best practice, the kind of boundaries, what is what is allowed, what is not.

00:48:06.532 --> 00:48:11.349
<v Max Lakkonen>I think that's the the important message that I would say max, thank you.

00:48:11.411 --> 00:48:21.246
<v Wojciech Węgrzyński>Thank you so much for for this lovely interview and it was great to hear about modeling from the new president of International Water Mist Association.

00:48:21.246 --> 00:48:24.387
<v Wojciech Węgrzyński>Anything you want to add as your final remark?

00:48:24.387 --> 00:48:33.965
<v Wojciech Węgrzyński>Perhaps a word of courage to those who will be faced with modeling water mist when to seek resources and where to find help in this journey.

00:48:35.902 --> 00:48:38.619
<v Max Lakkonen>I think the very first applicant to start with is obviously this IWMA position paper.

00:48:38.619 --> 00:48:41.547
<v Max Lakkonen>I think the very first applicant to start with is obviously this IWMA position paper.

00:48:41.547 --> 00:48:44.688
<v Max Lakkonen>I think that will give a good kickstart.

00:48:45.440 --> 00:48:46.947
<v Wojciech Węgrzyński>Is it available online already?

00:48:46.947 --> 00:48:47.561
<v Wojciech Węgrzyński>It?

00:48:47.581 --> 00:48:48.063
<v Max Lakkonen>will be.

00:48:48.063 --> 00:48:52.387
<v Max Lakkonen>I'm not sure, I haven't checked whether I presume it's already.

00:48:52.387 --> 00:49:01.784
<v Max Lakkonen>By this time this will come out, but it will be on IWMA webpage and I think that will guide with the best practice.

00:49:01.784 --> 00:49:16.556
<v Max Lakkonen>And then obviously it's then to talk with the organizations who have done it in the past, to talk also with the manufacturers if experimental data is needed, and I think that would be the way forward with this topic.

00:49:17.135 --> 00:49:17.677
<v Wojciech Węgrzyński>Fantastic.

00:49:17.677 --> 00:49:25.090
<v Wojciech Węgrzyński>Thank you, max, and all the best for your presidency, and looking forward what's going to come out of that.

00:49:26.164 --> 00:49:31.048
<v Max Lakkonen>It was a pleasure on my side, so thank you very much for this opportunity and that's it.

00:49:31.128 --> 00:49:32.072
<v Wojciech Węgrzyński>Thank you for listening.

00:49:32.072 --> 00:49:51.199
<v Wojciech Węgrzyński>After this episode it seems that the collaboration between the fire safety engineer, water mist companies, the suppliers of the systems and perhaps even the IWMA, the International Water Mist Association, is critical to succeed in modeling or even designing the water mist applications.

00:49:51.199 --> 00:50:02.467
<v Wojciech Węgrzyński>Of course there are standards, there's more widespread knowledge, but for the modeling tasks you seem to need some very specific details that you probably will get from the manufacturers.

00:50:02.467 --> 00:50:04.572
<v Wojciech Węgrzyński>But it may take some effort.

00:50:04.572 --> 00:50:06.943
<v Wojciech Węgrzyński>Max said it's quite straightforward.

00:50:06.943 --> 00:50:11.802
<v Wojciech Węgrzyński>However, in between the interview and today I had a phone call with a colleague.

00:50:11.802 --> 00:50:12.583
<v Wojciech Węgrzyński>He's a designer.

00:50:12.583 --> 00:50:17.543
<v Wojciech Węgrzyński>It was completely unrelated to the podcast episode but we were discussing Watomis.

00:50:17.543 --> 00:50:29.934
<v Wojciech Węgrzyński>He was asking questions about my opinions on Watomist systems and he told me that it's kind of rough because it's kind of black box, you know, with the manufacturers knowing everything and designers not knowing that much.

00:50:29.934 --> 00:50:32.242
<v Wojciech Węgrzyński>And you know it made me think.

00:50:32.242 --> 00:50:33.485
<v Wojciech Węgrzyński>It kind of made me resonate.

00:50:33.565 --> 00:50:53.327
<v Wojciech Węgrzyński>Even though we were highly optimistic with Max about this cooperation between the designer and the water mist companies in the podcast interview, I think in the real world there would still be examples where this knowledge is not that easily accessible, or perhaps it is and people just don't know it is.

00:50:53.327 --> 00:51:00.597
<v Wojciech Węgrzyński>In that case there's a communication issue, and you know I'm crazy about good communication between different silos in fire safety engineering.

00:51:00.597 --> 00:51:02.905
<v Wojciech Węgrzyński>Otherwise we can't solve the problems of fire safety engineering.

00:51:02.905 --> 00:51:06.460
<v Wojciech Węgrzyński>So, yeah, I would like to bring your attention to this topic.

00:51:06.460 --> 00:51:33.527
<v Wojciech Węgrzyński>I wonder what are your experiences working with water mist suppliers and obtaining the data that was necessary for you to succeed with your modeling tasks, and I wish you all the best in getting that knowledge easily, in obtaining the data and being able to do some good modeling that has clear objectives, that answers important questions and that solves real problems.

00:51:33.527 --> 00:51:40.802
<v Wojciech Węgrzyński>Thanks for listening to the Fire Science Show and more fire science coming your next week on Wednesday, as always.

00:51:40.802 --> 00:51:42.003
<v Wojciech Węgrzyński>Cheers, bye you.