The last time I had Xinyan on the show was in 2021, and we were all excited about the possibilities that AI could bring to Fire Safety Engineering and Smart Firefighting. Three years have passed, and while we are still excited, we can now talk about experiences. What worked and what did not? Where were the challenges, and what was simple? You can only learn that from brainstorming, you learn this by doing. Xinyan's team implemented dozens of algorithms for various projects, and it is this experience we try to explore today.

The episode is bitter-sweet. Even though considerable progress was made in the AI layer, it is still not possible to implement this in firefighting. The barriers that always separated fire science from firefighting are still in place, and it is even harder to cross them with such a novel approach. As always, communication is the key. However, in the midst of the research, a realization was made. AI does not work that great with humans, but works perfectly well with robots. This gives a beginning to a new chapter - AI-powered robotic firefighting, and hell, this is really exciting stuff.

Besides smart firefighting, we spend good time discussing use of AI in Fire Safety Engineering itself. Xinyan's team is developing practical tools to assist the designers and engineers, and they look promising. What is most interesteing is that the implementation of those tools reasembles how CFD was implemented back in the day - I have huge hopes for this technology.

If you want to read more about AI in PBD FSE, this is the paper you look for: https://www.sciencedirect.com/science/article/pii/S2352710221003867#appsec1

If you want to learn more about the work of the PolyU X Fire Lab, learn more on their up-to-date webpage: https://www.firelabxy.com/

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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.

Soot is perhaps the most complex product of combustion, and at the same time one of the most profound for our everyday fire safety engineering. The topic of soot is not getting much love in the world of fire science, so I’ve chosen to give you a broad introduction to this subject. In this episode of fire fundamentals we will go through:

· Soot creation from chemical perspective;

· Soot creation from practical perspective;

· Soot effects on radiation, toxicity and obscuration;

· Extinction coefficient and specific extinction coefficient;

· Soot yield and surrogate value of soot yield for complex fuels.

If you would like to follow up on this episode with some reading, I highly recommend:

· Bart Merci and Tarek Beji book „Fluid Mechanics Aspects of Fire and Smoke Dynamics in Enclosures”

· Jose Torero lecture “Prof. Jose Torero - Fire: A Story of Fascination, Familiarity and Fear” available at https://www.youtube.com/watch?v=cIY0litILRA&t=2082s

· W. Węgrzyński and G. Vigne, Experimental and numerical evaluation of the influence of the soot yield on the visibility in smoke in CFD analysis – the paper with the source of our surrogate value of soot yield for complex fuels in fire safety engineering https://www.sciencedirect.com/science/article/abs/pii/S0379711217301327?via%3Dihub

· G. Mulholland, C. Croarkin Specific extinction coefficient of flame generated smoke https://onlinelibrary.wiley.com/doi/epdf/10.1002/1099-1018%28200009/10%2924%3A5%3C227%3A%3AAID-FAM742%3E3.0.CO%3B2-9

· W. Węgrzyński, P. Antosiewicz, J. Fangrat, Multi-Wavelength Densitometer for Experimental Research on the Optical Characteristics of Smoke Layers, https://link.springer.com/article/10.1007/s10694-021-01139-5

· K. Börger, A. Belt, T. Schultze, L. Arnold, Remote Sensing of the Light-Obscuring Smoke Properties in Real-Scale Fires Using a Photometric Measurement Method, https://link.springer.com/article/10.1007/s10694-023-01470-z

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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.

In this episode of Experiments that Changed Fire Science we cover T. Jin’s experiments on the visibility in smoke – two experiments carried out in 1970 and 1971 in Japan that truly changed the way how we model fires and how we design fire safety in our buildings.

This episodes presents my recollection of Jin’s experiments, based on the published work – the seminal paper at the IAFSS in 1997 (https://publications.iafss.org/publications/fss/5/3/view/fss_5-3.pdf) and the original material published in Japanese in 1970 and 1971:

• Jin, T. (1970). Visibility through Fire Smoke (I). Bulletin of the Fire Prevention Society of Japan, 19(2).
• Jin, T. (1971). Visibility through Fire Smoke (II). Bulletin of the Fire Prevention Society of Japan, 21(1).

In the episode, I highlight the technical details of the experiments and their potential impact on the findings. I also present the overall model proposed by Jin, indicating the variables that influence it, and my recollection of how this model was implemented in modern fire safety engineering.

Further readings to this would be some of my papers:

• Węgrzyński, W., & Vigne, G. (2017). Experimental and numerical evaluation of the influence of the soot yield on the visibility in smoke in CFD analysis. Fire Safety Journal, 91(SI), 389–398. https://doi.org/10.1016/j.firesaf.2017.03.053
• Węgrzyński, W., Antosiewicz, P., & Fangrat, J. (2021). Multi-Wavelength Densitometer for Experimental Research on the Optical Characteristics of Smoke Layers. Fire Technology, 57(5), 2683–2706. https://doi.org/10.1007/s10694-021-01139-5

And a very recent paper by my collaborators from Wuppertal:

• Gnendiger, C., Schultze, T., Börger, K., Belt, A., & Arnold, L. (2024). Extinction coefficients from aerosol measurements. Fire Safety Journal, 146, 104110. https://doi.org/10.1016/j.firesaf.2024.104110

Please also visit episode https://www.firescienceshow.com/030-visibility-prediction-framework-with-lukas-arnold/ with my friend Lukas Arnold, on how we intend to change the visibility prediction in fire safety engineering!

This research was funded in part by National Science Centre, Poland in the grant OPUS 2020/39/I/ST8/03159.

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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.

Is evacuation of a community during a wildfire largely different from evacuation of a building? How much of the knowledge from the building fires is directly useful in planning and managing such an event, and what stuff is completely different? These are the lead questions for my today's interview with prof. Enrico Ronchi from Lund University and dr Max Kinateder from National Research Council Canada.

Both guests currently research the evacuation layer of the WUI problem – starting with the response of the endangered people, through choice of the mode of the transport, to solving the transportation models of such evacuations. A multilayered, multifaceted and interdisciplinary challenge, but one we need to have a good understanding of if we want to deliver good risk based, knowledge informed guidance for communities at risk.

In this episode, we got through their research pinpointing the difference between the building and a community evacuation. We touch the methods of research that are currently in used, and what kind of models they can inform. Finally, we get to talk about their recent experimental study during a fire drill in Roxborough Park, Colorado. This has literally happened a few days ago, and we can already discuss the challenges, and the first ‘anecdotal’ findings of the study.

Becoming open to the WUI problem and learning the challenges that are in front of us in this regard is critical to fire safety engineering, especially at the time when we observe Wildfire Safety Engineering becoming more of a real thing! I foresee that in future, a lot of us will work in the wildfire prevention / mitigation/contingency space, and I hope you will appreciate the fact you’ve learned it first from the Fire Science Show!

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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.

In the episode 10 of fire fundamentals together with David Morrisset, a nearly graduated PhD student from the University of Edinburgh, we explore the intricate dynamics of flame spread and its crucial role in fire safety engineering. David helps us differentiate between the two primary modes of flame spread, concurrent (imagine upward spread) and opposed (imagine downward spread), and explains how understanding these mechanisms can significantly enhance building safety and fire risk mitigation.

In this episode, we take a closer look at various materials like PMMA and timber and their unique fire behaviors. We also examine the complexities of flame spread on charring solids such as timber, discussing how pyrolysis and the resulting char layer influence heat transfer and flame behavior.

Lastly, we dissect the heat transfer mechanisms in various materials, from foams to solid slabs, and how factors like orientation and material properties affect flame spread rates. David highlights the balance between gas phase and solid phase heat transfer and the importance of precise modeling to predict flame behaviors accurately.

Phemonena discussed here:

• flame spread definition
• concurrent vs opposed flame spread
• regimes of flame spread
• driving mechanisms of flame spread

Further reading:

• Quantifying the controlling mechanisms of opposed flow flame spread: Influence of orientation, material, and external heating
• Characterization of Flame Spread Over PMMA Using a Temperature Reconstruction Method
• The relative position of pyrolysis onset and flame front location for downward flame spread

And even though we did not have time to discuss diagnostics in the episode, you can check this crazy paper of David:

• Assessment and application of phosphor thermometry for spatially resolved surface temperature measurements during downward flame spread

Cover image: edited from Figure 1 in https://doi.org/10.1016/j.firesaf.2023.104048

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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.

With two Directors at NFPA - Michele Steinberg and Birgitte Messerschmidt, I'm trying to find an answer to a burning question - "what really is the WUI problem?" The WUI is not just a line on a map with an X distance from the forest... In this episode we try to define what it is, and who is in danger. Instead of our usual conversations looking into characteristics of burning forests, or seeking the impact of detailing in construction, in this episode we try to take a birds eye view and identify the problem across the scales and frameworks. From seeking out good definitions and their impact on policymaking, through technical solutions up to creating new testing and certification systems.

So where are the answers? Actions across the scales at homeowner - community - regional levels, in which they are interconnected and optimal. A fireproof house in the middle of wrongfully managed area will not be of great difference… As well as a dangerous premise at the edge of the forest… The outcome of a WUI fire incoming will be an outcome of propper actions taken at every level.

We need new solutions. Scallable ones. We need better testing and standardization, new listings. We need to find ways to involve the private sector and create interesting pathways for fire safety engineers to work with people at risk, at whatever scale. The future looks promising, let's make sure we are a part of it.

Some recommended resources I received from my eminent Guests:

• Impact of smoke in WUI fires: https://www.nfpa.org/en/news-blogs-and-articles/nfpa-journal/2024/02/13/research-column-spring-24
• Defining the WUI: https://www.nfpa.org/news-blogs-and-articles/nfpa-journal/2024/04/30/defining-the-wui
• Preparing homes for wildfire (home ignition zone): https://www.nfpa.org/en/education-and-research/wildfire/preparing-homes-for-wildfire
• The Firewise USA Recognition program: https://www.nfpa.org/en/education-and-research/wildfire/firewise-usa/become-a-firewise-usa-site
• Outthink Wildfire policy initiative: https://www.nfpa.org/en/Education-and-Research/Policy-and-Action/Outthink-Wildfire

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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.

• pressure inlets/outlets [open];
• velocity boundary conditions [vents];
• mass flow inlets;
• fans and HVAC models.

• heat transfer at walls;
• shear at walls.

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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.

A critical velocity episode... who would have thought? Even though I'm not an enthusiast of this approach, I have to admire the new science and researchers striving to improve it.

This week I welcome Conrad Stacey and Michael Beyer from Stacey Agnew to talk about their recent developments. We'll take you through the historical development of this concept since its inception in 1958, examining key variables like tunnel height and heat release rate along the way. We go into the Memorial Tunnel experimental project, and we discuss the context and the economic implications of recent updates to the NFPA 502 standards, exploring how changes in required ventilation speeds have impacted tunnel design costs and stirred controversy.

Conrad and Michael provide fresh insights into the complexities of tunnel smoke control, the distinction between critical and confinement velocities, and the significance of fire intensity in tunnel environments. Focusing on the historical Memorial Tunnel study, they explain the experiments that have been the source of our current models and how revisiting this data with modern CFD techniques allowed them to analyze this even further. With their newly proposed model for assessing critical velocity, the HRR of the fire is not considered as an important variable anymore, and replaced with the fire intensity (HRR Per-Unit-Area). This follows an observation that it is just the front of the fire that interacts with the incoming air, and thus making fire larger by making it 'longer' does not influence the outcomes - a new feature consistent with their newly defined model and Memorial Tunnel data.

You can read their study here: https://www.researchsquare.com/article/rs-4278205/latest

Some previous takes on the critical velocity by the team:

• CRITICAL OF CRITICAL VELOCITY – AN INDUSTRY PRACTITIONER’S PERSPECTIVE
• Critical velocity and the significance of the imminent retraction of 2020 NFPA 502’s Annex D critical velocity equations Part One
• Critical velocity and tunnel smoke control Part 2 - Filling the NFPA 502 void

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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.