Fire Science Show

This week I've invited a guest, that I was looking to talk to for a good while... Dr Ingo Riess from Riess Ingenieur-GmbH is someone I look up to in the field of tunnel fire safety, in which I am very active in the last few years. In this chat, we had the chance to go through the concept of tunnel resiliency and calculate the risk related to the whole road network, rather than just a tunnel on its own. This is such a refreshing concept, in which the goal - maximizing public safety - is well defined, and thanks to that, smart decisions can be made. And these decisions are not always to make the tunnel a bit safer - in some cases, it may be just better to invest in other safety infrastructure. This holistic view opens new pathways and possibilities and makes investments in fire safety really reasonable. I absolutely love it, and it is something I wish we can implement in my own country. Outside resilience, we also had a good chance to discuss the ventilation and modelling, design fires and some tough choices the engineers have to make when refurbishing tunnels. If you have anything to do with tunnels, this episode is definitely for you. And if you do not, still can be inspiring, as the world of tunnels is one the forefront of applying risk-based concepts in performance-based engineering. Something, that the rest of the world must eventually catch up.
Make sure to check Ingo's ResearchGate, where he stores all the magnificent reports we have talked about (and many more we did not).
https://www.researchgate.net/profile/Ingo-Riess
Also, give a chance to the Graz Tunnel Safety and Ventilation conference, which always delivers the best content related to the fire safety of tunnels:
https://www.tunnel-graz.at/

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

When the flaming combustion stops and the raging inferno disappears, the environment is still far away from a stable, stationary state. The heat emitted by the fire and accumulated by the structural elements is still on the move, travelling through the members until it gets eventually dissipated. As parts of the structure get heated, some processes will occur, that may influence their load-bearing capacity and other properties. This is nothing new, we recognize this as an obvious process within the so-called "decay" phase of the fire.
What is new, though, are some recent observations related to the behaviour of timber elements in this phase of the fire. Today's guests Thomas Gernay and Jochen Zehfuss (along with a team that I call EU Fire All-Star Team) have performed a very precise study in which they have shown on one example the exact conditions in which the load-bearing capacity is lost in the decay phase by a column. If you missed that, they made quite an impression on LinkedIn (check the post and discussion here). In their experiments carried out within a well-controlled furnace environment, the variable they played with was the duration of the heating phase. It allowed them to find out two separate behaviours - one in which the column collapses in the decay phase, and one (not very different) in which the collapse does not happen. To learn more, please join us in the episode, and for sure - read the research paper provided in here.
If you would like a quick insight, I will also steal some text from Thomas's post on LinkedIn, as he did a great job summarizing their research. So here is his short comment:
"Two of the columns were subjected to ISO 834 heating until failure. They failed after 55 and 58 min (-> standard fire resistance).
Two other columns were subjected to 15 min of ISO 834 heating followed by controlled cooling. Flames self-extinguished after 40 min. But the columns still failed during the cooling phase, respectively after 98 and 153 min.
The load on the timber columns was constant throughout the tests. What changes between 15 min (end of heating) and 153 min (failure)? Heat transfer. The temperature of the inner parts of the column section continues increasing. Hence the strength continues decreasing.
Flaming and charring are not necessary for this inner temperature increase. And the absence of flaming is not a good predictor that the column is safe (see video).
By better understanding these phenomena, we can design to account for them - and achieve safe and resilient timber designs, including for burnout resistance when needed. Numerical modelling can support this objective. But simple methods based on charring rate fall short because they don't account for the slow heat transfer processes during the cooling phase."

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

It is interesting to see changes in our profession that happen directly in front of our lives. Climate change and in consequence the changes in the wildfire patterns are one such obvious shift. In Poland, we do not ever have a ‘wildfire’ season, and I was kind of surprised when I discovered this is a thing in the South or in other parts of the world. Unfortunately, we do not have it *yet*. Some years ago devastating wildfire season happened in Sweden. There has been an emergency in northern parts of Russia as well. The summers are more dry – I thought that this is the driver of challenge, however, as with almost everything in fire science, the answer is more complicated.

I have invited Nieves Fernandez-Anez from Western Norway University of Applied Sciences to discuss what is the ‘north’ doing to get ready for the coming threat. Nieves told me we do not need to reinvent the wheel – a lot of solutions, methods, approaches and policies do already exist. However, the wheel has also not been tested on all roads... Some things that can work in Spain or Greece won’t ever be feasible in the Scandinavia. Cultural and societal differences must be understood and accounted for when transposing solutions. The same comes to our models – they need to account for local vegetation, and its growth patterns. A challenge in itself, as we need a rapid increase in the amount and quality of information we have at hand.

I was a bit naïve coming to the episode, and the issue seems significantly more complicated. This is obviously an issue that a single researcher won’t handle. But here, another reason why I have invited Nieves. She is one of researchers who really get a lot out of collaborations in the COST network. Previously in COST Action Fire Links and now in the COST action on extreme wildfires. These networks connect scientists from different backgrounds and different regions, to create a thriving environment for knowledge exchange and crafting new ideas that respond to the new problems.

If you would like to learn more about changes in wildfires in Europe, refer to this paper.

COST Action Fire Links

COST Action european Network on Extreme fiRe behaviOr (NERO) (just started and open!)
Cover image - picture of wildfires near Ljusdal in Sweden, 2018, NASA Earth Observatory images by Lauren Dauphin and Joshua Stevens, using MODIS data from LANCE/EOSDIS Rapid Response and the Level 1; after Wikipedia: https://pl.wikipedia.org/wiki/Po%C5%BCary_las%C3%B3w_w_Szwecji_(2018)

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

I've finished my first large research grant! I guess that makes me a 'real' scientist now. Came here today to share some most interesting aspects of this project with you. Not going to bore you all about the wind and fire interaction physics (hey, there is an entire episode 50 devoted to that!), but rather talk about challenges and stuff that perhaps will matter if you would like to engineer a case similar to one we have studied.
So in this podcast episode, we will go into:

• How our framework for wind and fire coupled modelling worked out in practice (read more about the framework here Wind and Fire Coupled Modelling part 1 - Literature Review and here Wind and Fire Coupled Modelling part 2 - Best Practice Guidelines )
• How we had to go miles to modify the ABL profile so our wind predictions at the location of the fire are spot on
• A bit on design fire choice, but plenty more in here: 135 - Contemplating a design fire for car parks
• And most importantly, how we handled the mass amount of data generated in 336 CFD simulations within the project. Our unique approach to statistics, indexing and risk.

The promised webinars will be uploaded soon, and you will find the link here.
Badania przedstawione w odcinku podcastu przeprowadzono w projekcie realizowanym an podstawie umowy UMO-2020/37/B/ST8/03839 do projektu badawczego nr 2020/37/B/ST8/03839 pt. Skutki oddziaływania wiatru na pożary budynków w wieloparametrycznej ocenie ryzyka z wykorzystaniem metod numerycznych.
Grafika autorstwa P. Jamińska-Gadomska (ITB) oraz P. Prusiński (NCBJ) w ramach współracy pomiedzy ITB a NCBJ w projekcie EuroCC (No 951732)

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.

I approach modelling water mist with caution. Not that I don't understand it, but because I lack clarity in the goals and objectives, as well I'm usually aware I may not deliver the expectations of my clients in terms of the physical phenomena I am capturing... And I'm not the only one like this. In this podcast episode I explore the world of water mist with Dr Max Lakkonen from IFAB, who has just been chosen as the new President of the International Water Mist Association (IWMA),
Max dives into the history and evolution of water mist technology, explaining how a catastrophic fire on a Scandinavian Star Cruise liner 35 years ago led to its commercial introduction. Discover why understanding droplet size is crucial for optimising water mist systems and why it's important to understand these systems with a clear understanding of objectives to achieve effective fire safety solutions.
Max discusses the necessity of extensive experimental testing to account for different nozzle types, pressures, and flow rates, highlighting the complexity involved in designing these systems. We also touch on the importance of industry collaboration and the role of organizations like IWMA in bridging the gap between specialized water mist companies and fire safety engineers, ultimately ensuring the dissemination of crucial information and best practices.
Dive into the intricacies of CFD modelling in fire safety engineering, especially for water mist systems. Max brings to light the limitations of relying solely on CFD without experimental validation and the benefits of using CFD for preliminary studies to save both time and costs. We address the unique challenges of modelling cooling effects, fire suppression in tunnels, and the need for best practices and guidelines in fire safety engineering. Listen in to gain valuable insights from one of the leading experts in the field and understand why practical application often trumps academic theory in real-world fire control scenarios.
Most importantly, the CFD Position Paper we have promised to you is available to download now!!!
Make sure to visit the International Water Mist Association site for more resources and the necessary connection with the industry.
The cover image was captured at the Baltic Fire Laboratory during ITB-FRISSBE Summer School. If you want to see it live, pay attention to our announcements on LinkedIn, and perhaps we can see each other next summer!

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The Fire Science Show is produced by the Fire Science Media in collaboration with OFR Consultants. Thank you to the podcast sponsor for their continuous support towards our mission.