Heat release rate (HRR) of the design fire is the most important parameter in assessing building fire hazards. However, HRR in room fire was only studied by computational fluid dynamics (CFD) in most of the projects determining fire safety provisions by performance-based design. In contrast to ten years ago, officers in the Far East are now having better knowledge of CFD. Two common questions are raised on CFD-predicted results on describing free boundaries; and on computing grid size. In this work, predicting HRR by the CFD model was justified with experimental room pool fire data reported earlier. The software fire dynamics simulator (FDS) version 5 was selected as the CFD simulation tool. Prescribed input heating rate based on the experimental results was used with the liquid fuel model in FDS. Five different free boundary conditions were investigated to predict HRR. Grid sensitivity study was carried out using one stretched mesh and multiple uniform meshes with different grid sizes. As it is difficult to have the entire set of CFD predicted results agreed with experiments, macroscopic flow parameters on the mass flow rate through door opening predicted by CFD were also justified by another four conditions with different ventilation factors. 1. Introduction There are many big construction projects [1] with difficulties to comply with the fire codes while developing in the Far East. Performance-based design (PBD) was then applied to determine fire safety provisions. However, budget allocated on fire safety used to be small, resulting in a lack of full-scale burning tests to measure heat release rate. There are even no resources allocated in some places like Hong Kong to compile a database of heat release rate for local products including train compartments of the railway system [2] as in Japan, China, and Korea. Consequently, wrong concept was adopted in estimating the heat release rate, taking “average value” as “peak value” in many projects submitted to be evaluated by the principal author [1]. At most, computational fluid dynamics (CFD) was applied [3, 4] in hazard assessment. Fire behavior involves complex dynamics driven by critical events, such as the ignition of secondary items, flashover, window breakage, and falling down of glass systems. All these phenomena have not yet been modeled realistically without using empirical parameters. Authorities having jurisdictions (AHJ) are now more knowledgeable in fire science and engineering. Taking Hong Kong as an example, a huge percentage of senior officers approving fire projects are well trained and
References
[1]
W. K. Chow, “Performance-based design on fire safety provisions in the Far East,” in Professional Development Conference and Exposition, Engineering Technology Conference, Portland, Ore, USA, October 2011.
[2]
W. K. Chow, “A discussion on fire safety for subway systems in Hong Kong,” in Exchange Meeting for SFPE Asia-Oceania Chapters – Transportation Fire Safety, Korea Railroad Research Institute & SFPE Korean Chapter, Seoul, Korea, April 2011.
[3]
G. Cox and S. Kumar, “Modelling enclosure fires using CFD,” in SFPE Handbook of Fire Protection Engineering, pp. 3-194–3-218, Natl Fire Protection Assn, Quincy, Mass, USA, 4th edition, 2008.
[4]
K. B. McGrattan, B. Klein, S. Hostikka, and J. E. Floyd, “Fire Dynamics Simulator (Version 5), User's Guide,” NIST Special Publication 1019-5, National Institute of Standards and Technology, Gaithersburg, Md, USA, 2009.
[5]
S. S. Li and W. K. Chow, “Application of computational fluid dynamics in simulating fire-induced air flow in large halls,” in 8th Asia-Oceania Symposium on Fire Science and Technology, Melbourne, Australia, December 2010.
[6]
W. K. Chow, C. L. Chow, and S. S. Li, “Simulating smoke filling in big halls by computational fluid dynamics,” Modelling and Simulation in Engineering, vol. 2011, Article ID 781252, 16 pages, 2011.
[7]
W. K. Chow, “Fire safety desired in the new airport terminal,” Lecture for 40th Anniversary, University of Science and Technology of China, Hefei, Anhui, China, September 1998.
[8]
W. K. Chow, “On the "cabins" fire safety design concept in the new Hong Kong airport terminal buildings,” Journal of Fire Sciences, vol. 15, no. 5, pp. 404–423, 1997.
[9]
J. C. Jones, “Comment on fire load densities,” International Journal on Engineering Performance-Based Fire Codes, vol. 10, no. 3, p. 75, 2011.
[10]
J. H. Klote, “Computer modeling for smoke control design,” Fire Safety Journal, vol. 9, no. 2, pp. 181–188, 1985.
[11]
D. Madrzykowski and D. W. Stroup, “Flammability Hazard of Materials,” in Fire Protection Handbook, A. E. Cote, C. C. Grant, J. R. Hall Jr., and R. E. Solomon, Eds., vol. 1, Chapter 3. Section 2, pp. 31–48, National Fire Protection Assoc., Quincy, Mass, USA, 20th edition, 2008.
[12]
J. G. Quintiere, Principles of Fire Behavior, Delmar Cengage Learning, 1998.
[13]
V. Babrauskas and R. D. Peacock, “Heat release rate: the single most important variable in fire hazard,” Fire Safety Journal, vol. 18, no. 3, pp. 255–272, 1992.
[14]
W. K. Chow, Y. Gao, H. Dong, G. Zou, and L. Meng, “Full-scale burning tests on heat release rate of gasoline fire with water mist,” Journal of Applied Fire Science, vol. 11, no. 1, pp. 21–40, 2002.
[15]
W. K. Chow, Y. Gao, H. Dong, G. W. Zou, Z. Luo, and L. Meng, “Experimental studies on minimum heat release rates for flashover with oxygen consumption calorimetry,” Architectural Science Review, vol. 46, no. 3, pp. 291–296, 2003.
[16]
Q. Chen, “CFD for simulating air distribution in buildings: The state of the art, challenges, and opportunities,” in Proceedings of the 11th International Conference on Air Distribution in Rooms (ROOMVENT '09), pp. 23–31, Busan, Korea, May 2009.
[17]
C. L. Chow, “Air flow rate across vertical opening induced by room heat sources,” International Journal on Architectural Science, vol. 8, no. 1, pp. 11–16, 2011.
[18]
K. McGrattan, S. Hostikka, J. Floyd et al., “Fire Dynamics Simulator (Version 5): Technical Reference Guide,” NIST SP 1018, NIST Special Publication 1018-5, National Institute of Standards and Technology, Gaithersburg, Md, USA, 2009.
[19]
C. L. Chow and W. K. Chow, “A brief review on applying computational fluid dynamics in building fire hazard assessment,” in Fire Safety, I. S？gaard and H. Krogh, Eds., Nova Science, 2009.
[20]
N. C. Markatos, M. R. Malin, and G. Cox, “Mathematical modelling of buoyancy-induced smoke flow in enclosures,” International Journal of Heat and Mass Transfer, vol. 25, no. 1, pp. 63–75, 1982.
[21]
N. C. Markatos and G. Cox, “Hydrodynamics and Heat Transfer in enclosures containing a fire source,” PCH. Physicochemical Hydrodynamics, vol. 5, no. 1, pp. 53–66, 1984.
[22]
A. Schaelin, J. van der Maas, and A. Moser, “Simulation of airflow through large openings in buildings,” in Proceedings of the ASHRAE Winter Meeting, pp. 319–328, Anaheim, Calif, USA, January 1992.
[23]
E. R. Galea and N. C. Markatos, “The mathematical modelling and computer simulation of fire development in aircraft,” International Journal of Heat and Mass Transfer, vol. 34, no. 1, pp. 181–197, 1991.
[24]
G. Hadjisophocleous and Y. J. Ko, “Impact of various parameters on the CFD predictions of atrium smoke management systems,” ASHRAE Transactions, vol. 115, pp. 263–270, 2009.
[25]
R. Yin and W. K. Chow, “Building fire simulation with a field model based on large eddy simulation,” Architectural Science Review, vol. 45, no. 2, pp. 145–153, 2002.
[26]
ASHRAE Handbook–Fundamentals, American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), Atlanta, Ga, USA, 2001.
[27]
R. D. Peacock, P. A. Reneke, W. D. Davis W., and W. W. Jones, “Quantifying fire model evaluation using functional analysis,” Fire Safety Journal, vol. 33, no. 3, pp. 167–184, 1999.
[28]
W. K. Chow and G. W. Zou, “Numerical simulation of pressure changes in closed chamber fires,” Building and Environment, vol. 44, no. 6, pp. 1261–1275, 2009.
[29]
K. B. McGrattan, H. R. Baum, and R. G. Rehm, “Large Eddy simulations of smoke movement,” Fire Safety Journal, vol. 30, no. 2, pp. 161–178, 1998.
[30]
B. Merci and K. Van Maele, “Numerical simulations of full-scale enclosure fires in a small compartment with natural roof ventilation,” Fire Safety Journal, vol. 43, no. 7, pp. 495–511, 2008.
[31]
G. W. Zou and W. K. Chow, “Evaluation of the field model, fire dynamics simulator, for a specific experimental scenario,” Journal of Fire Protection Engineering, vol. 15, no. 2, pp. 77–92, 2005.
[32]
J. Hietaniemi, S. Hostikka, and J. Vaari, “FDS simulation of fire spread comparison of model results with experimental data,” VTT Working Papers 4, 2004.
[33]
P. Smardz, Validation of Fire Dynamics Simulator (FDS) for forced and natural convection flows, M.S. thesis, University of Ulster, 2006.
[34]
A.Z. Moghaddam, K. Moinuddin, I. R. Thomas, I. D. Bennetts, and M. Culton, “Fire behaviour studies of combustible wall linings applying FDS,” in Proceedings of the 15th Australasian Fluid Mechanics Conference, Sydney, Australia, 2004.
[35]
I. R. Thomas, K. A. M. Moinuddin, and I. D. Bennetts, “The effect of fuel quantity and location on small enclosure fires,” Journal of Fire Protection Engineering, vol. 17, no. 2, pp. 85–102, 2007.
[36]
V. Babrauskas and R. B. Williamson, “Post-flashover compartment fires: basis of a theoretical model,” Fire and Materials, vol. 2, no. 2, pp. 39–53, 1978.
