CFD Study of Combustion Behavior of Single and 3 3 Arrayed Huge Oil Tanks in Free Burning and Whirling Conditions

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1 CFD Study of Combustion Behavior of Single and 3 3 Arrayed Huge Oil Tanks in Free Burning and Whirling Conditions Satoh K., Liu N. A.*, Lei J., Xie X., Gao W. State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui, China *Corresponding author liunai@ustc.edu.cn ABSTRACT Huge oil tanks filled with large amounts of flammable fuel have the potential to cause large fires and there have been many serious accidents due to huge oil tank fires. It is not only of great difficulty to suppress a fire occurring in one of these tanks, but also of extreme danger for firefighters if a fire whirl occurs, since the fire whirl will induce intense heat radiation and strong wind. In our previous study we numerically studied huge fire whirls in a large oil tank depot. This paper presents a further CFD simulation study to clarify the more detailed combustion behavior of fire whirls in single and multiple oil tanks. Detailed combustion characteristics such as heat release rates, velocities of whirling flames and radiative heat flux are examined for single and (3 3) arrayed oil tanks placed in a tall channel with four corner gaps. In a single oil tank fire, the fire whirl lengths are about 10 times the oil tank diameter, and in (3 3) oil tanks with a diameter of 40 m, a tall fire whirl more than 20 times the single oil tank diameter is generated. In single whirling fires, the radiative heat flux on the fuel surface reaches a maximum in the center of the tank, which induces a large amount of fuel evaporation therein. However, the fuel vapor moves upward without combustion due to insufficient oxygen. The critical merging distance in the (3 3) arrayed fire is inversely proportional to the square root of the tank diameter. The rotational cycles of whirling flames of single and (3 3) arrayed fires are found to be almost proportional to the inverse of the square root of the tank diameter or the array length. A method to prevent fire whirl generation is also preliminarily examined. KEYWORDS: Oil tank fire, CFD simulation, critical fire merging distance, fire whirl, HRR. NOMENCLATURE D oil tank diameter (m) Q heat release rate (HRR) (kw) d inter-tank distance (m) r distance from the center d cr critical merging distance (m) of oil tank (m) d x grid length in x direction (m) Ra radiative heat flux (kw/m 2 ) d y grid length in y direction (m) s space between two d z grid length in z direction (m) adjacent tanks (m) f rotational cycle (Hz) t time (s) G corner gap width (m) V wind velocity (m/s) g gravitational acceleration (m/s 2 ) w width (m) h height (m) x, y, z coordinates L length of (3 3 ) array (m) (z: gravitational direction) L x domain length in x direction (m) X c channel width (m) L y domain length in y direction (m) Y c channel height (m) L z domain length in z direction (m) Superscripts L f flame length (m) * dimensionless value Proceedings of the Eighth International Seminar on Fire and Explosion Hazards (ISFEH8), pp Edited by Chao J., Liu N. A., Molkov V., Sunderland P., Tamanini F. and Torero J. Published by USTC Press ISBN: DOI: /c.sklfs.8thISFEH

2 Proceedings of the Eighth International Seminar on Fire and Explosion Hazards (ISFEH8) INTRODUCTION The accident probability at nuclear power plants was believed to be nearly zero, before the nuclear power plant accident in Japan due to the Great Earthquake in The incident proved that nuclear power plants may have a potential to cause disastrous accidents far beyond the outcome predicted by probability analysis [1]. Similarly, huge oil tanks filled with large amounts of extremely flammable fuel may have the potential to cause large fires. Many serious accidents caused by huge oil tank fires have been reported [2-4], reflecting the increasing number of large oil storage tanks constructed in the world [5]. If a fire whirl occurs in a huge oil tank fire, fire extinguishment would be extremely difficult and dangerous for firefighters, because of the extremely intense heat radiation and strong induced wind. Usually the only possible outcome is to wait for the fire to burn itself out. This study was motivated by this problem. To date, there have been many studies of fire whirls [6-18] related to city fires and forest fires. However, few studies are concerned with the fire whirls induced by oil tank fires. Fire whirls induced by fires of large oil tanks may produce extremely tall flames, together with intense heat radiation and strong wind. In laboratories, even in weak ambient flow conditions, fire whirls can be easily produced by using oil pans. However, there is scarce information on huge fire whirls in large oil tanks. In the previous works [19-21], the authors conducted some preliminary numerical studies on huge fire whirls in a huge oil tank depot. The CFD study indicated that an extremely strong fire whirl with a flame length of 1000 m can be generated. However, details of combustion behavior of such huge fire whirls have not been fully clarified. In this paper, by using a fire whirl generation tool in CFD simulations with a combustion model, we further conduct a numerical study to clarify the details of fire whirls in single and (3 3) arrayed huge oil tanks. The diameters of the oil tanks range from 0.2 to 80 m. The burning rates, velocities of whirling flames, radiation, heat release rates (HRR), temperatures, and flame whirling cycles are investigated, and a method to prevent or terminate the fire whirls is also discussed. SIMULATION METHOD Schematics of free burning and whirling flames of single and (3 3) n-heptane fires Figure 1. Schematics of an array of (3 3) oil tanks. (a) (b) (c) Figure 2. Vertically tall channel with four corner gaps; (a) single fire; (b) 3 3 array fire; (c) top view of rotational flow. Generally fire whirls are caused by winds, for example in multiple fires in open spaces as shown in Fig. 1. However those fire whirls are not stable. This study aims to examine characteristics of stable fire whirls. The simulations are conducted on single and (3 3) n-heptane (C 7H 16) flames in free burning and whirling conditions, by using the fire software FDS (version 6) developed by NIST [22-24]. Figure 1 shows a (3 3) array of oil tanks, for which each oil tank has a uniform size and all the tanks are placed with a uniform inter-tank distance. For both single steel tank and (3 3) steel tank arrays, it is assumed that the fuels of n-heptane burn in an open calm condition. The diameter of each tank varies from D=0.2 to 80 m, and the distance (d) between adjacent oil tanks in the (3 3) array is varied to examine the merging behavior. Fig. 2 shows a vertically long channel (height Y c and width X c), which has one corner gap (width G) on each face, to induce a whirling flame. A cylindrical 464

3 Part II Fire channel may be better to cause an axisymmetric smooth rotation, but the channel with a square cross section is used in this study for simplicity. In the real natural environment, of course, there may be no square channel as shown in Fig. 2, but the fire whirls produced in the channel may give the extremely strong cases of fire whirls, to consider the adequate strategy for worst cases for firefighting. As shown in Fig. 2(c), when the fuel begins to burn, the fire entrains the surrounding air into the flame, producing a self-induced wind entering into the channel through the four corner gaps and moving along the walls. The wind is entrained into the channel at an angle, generating a rotational wind field, which in turn creates a fire whirl. However, in the early stage, the fire with a small flame length leans towards the ground and whirls around, as suggested by Lei et al. [11]. When the temperatures of the channel walls increase due to the radiation, the leaning and whirling flame straightens up and becomes elongated. The burning rate of the fuel and the temperature rise of the channel walls increase due to the radiation from the whirling flame. The higher wall temperature helps increase the buoyant flow in the channel, which plays an important role in the stability of the whirling flame. Effect of grid size on heat release rate It is known that CFD simulation results are affected by grid size and grid numbers [25-26]. The dependence of the time-averaged heat release rate (HRR [22-24]) on grid is investigated by examining a single free burning n-heptane fire with D=40 m in a calm condition. In this study HRR is calculated by the mass loss rate of fuel and therefore includes radiative heat loss, about 15% of the total heat release rate. Four cases are compared with the different numerical domain sizes as shown in Table 1, where d x and d y are the horizontal grid size and d z is the vertical grid size in Cartesian coordinate system with z being the gravitational direction. It is found that, for a fixed numerical domain, smaller grids result in smaller HRR values, although the sensitivity test is not always sufficiently conclusive. There are no experimental data of burning rate of an oil tank over 40 m in diameter. Blinov and Khudyakov [27] showed the fuel level regression rate of gasoline and kerosene to be about 4 mm/min for oil tanks with diameters of m. If this value can be extended to be used for an n-heptane tank with a diameter of 40 m, the HRR is estimated to be roughly kw, which is lower than the estimated values of HRR shown in Table 1. This deviation may be partly due to the fact that the selected grid sizes in the current simulations are too large as they are restricted by the available computers. More studies are needed for a grid sensitivity test, together with the study of thermal interaction effect between the fires and the surroundings of the oil tanks. Table 1. Dependency of HRR of D=40 m fire on grid size. dx (m) dy (m) dz (m) HRR ( 10 6 kw) Case A Case B Case C Case D

4 Proceedings of the Eighth International Seminar on Fire and Explosion Hazards (ISFEH8) RESULTS OF SIMULATIONS Effect of channel height on combustion behavior of single flame in whirling conditions The whirling combustion behavior of a single flame of n-heptane is examined in a calculation domain with dimensions of 100 m 100 m 500 m. Fig. 3 shows the profiles of n-heptane flames (D=40 m), whirling in a channel (width X c=82 m, heights Y c=300 to 500 m) with four corner gaps (G=5 m). For Y c=300 to 500 m, the maximum values of flame length (L f) vary around 400 m with a deviation of 50 m, which suggests that beyond a certain point the channel height has a minor effect on the whirling flame length. However, a channel shorter than 200 m produces a shorter flame than that in Fig. 3(a), with unstable whirling motion. This tendency is also seen in the cases of smaller flames between D=0.2 m and 20 m. The corner width (G) considerably affects the length of the single whirling flame, and the maximum flame length occurs at G=5-10 m. When the gap width is less than G=5 m or larger than G=20 m, the whirling flame becomes unstable, leaning toward the walls, which makes the flame length decrease. (a) Yc=300 m (b) Yc=350 m (c) Yc=460 m (d) Yc=500 m (e) Yc=500 m Figure 3. Whirling profiles of n-heptane flames (HRR, D=40 m) in a channel with four corner gaps (G=5 m), varying a channel height (Lz=500 m), (a) to (d): 3-dimensional view, (e): 2-dimensional view. Dimensionless velocity and radiative heat flux of single n-heptane flame Fig. 4 shows the dimensionless centerline velocity (V*) of single free burning and whirling n-heptane flames as a function of dimensionless height in the center of the tank. The dimensionless velocity is defined by V*=V/(g D) 0.5. (1) The relationships of whirling and free burning conditions are well correlated as a function of dimensionless height. The velocities are all time-averaged. The maximum velocity is at the height of h/d=3.2 and 5.6 for free burning and whirling conditions, respectively, and the maximum velocity of the whirling flame is about 1.3 times larger than that of free burning flames. Fig. 5 shows the radiation (perpendicular component to the surface) due to a single fire, reaching the fuel surface, as a function of dimensionless radius. For free burning conditions, the maximum value of the radiation is near the oil tank edge, while the radiation reaching the center of the fuel surface is weak. For whirling conditions, the maximum value of the radiation is near the oil tank center, with considerably strong radiation reaching the center of the fuel surface (about 3 times higher compared with that of the free burning), suggesting much stronger fuel evaporation than that in the free burning condition. However, there is insufficient oxygen for combustion of the increased fuel vapor in the central area in the whirling flame. The flame and evaporated fuel gases are transported upward by the swirling flow without combustion. Thus, the flame lengthens and the fuel burns in the higher region, since the oxygen is only supplied at the thin flame surface. 466

5 Part II Fire Figure 4. Dimensionless velocity of single n-heptane flame, for free burning and whirling conditions, as a function of height in the center of the tank. Figure 5. Radiative heat flux as a function of dimensionless distance on the fuel surface. Heat release rate and flame length vs. tank diameter Fig. 6 shows the heat release rates of single free burning and whirling n-heptane flames as a function of tank diameter (D= m). The heat release rate linearly depends on the square root of the tank diameter for both free burning and whirling conditions. Whirling fires produce heat release rates about 2 to 3 times higher than those of free burning flames. The experimental results by Blinov and Khudyakov [27] are slightly lower than these simulation results, as shown in Fig. 6. Fig. 7 shows the time averaged flame lengths of single free burning and whirling n-heptane fires as a function of tank diameter. The dimensionless flame length (L f/d) is almost constant or slightly decreasing with the tank diameter, with values within 9-10 for whirling conditions and 3-4 for free burning conditions. The flame lengths for larger tanks in free burning conditions are slightly different from the experimental results by Blinov and Khudyakov [27], but the free burning flames with smaller tank diameters are similar to the experimental results by Zhou et al. [14], Satoh et al. [15] and Hamins et al. [28]. Figure 6. Heat release rate of n-heptane flame, for free burning and whirling conditions, as a function tank diameter. Figure 7. Comparison between simulation results and experiments of dimensionless flame length vs. tank diameter. Combustion profiles of (3 3) arrayed fires Fig. 8 shows the profiles of (3 3) n-heptane flames with D=40 m, as a function of inter-tank distance (d). Figs. 8(a) and (b) show the three-dimensional distribution of HRR and oxygen distribution in the vertical central plane, respectively. The critical merging distance (d cr), defined as the distance at which all the flames merge into the center, is roughly judged from both profiles shown in Figs. 8(a) and (b). Profiles of fuel and CO 2 are also used. When the distance d is less than 70 m, the flames of (3 3) fires merge into the center. Additionally, many cases are examined between d=60 m and 74 m. Finally the 467

6 Proceedings of the Eighth International Seminar on Fire and Explosion Hazards (ISFEH8) critical merging distance d cr is determined at 70 m. Fig. 9 shows the plan view of profiles of (3 3) flames with D=60 m, as a function of inter-tank distance, based on the fuel distribution. For D=20, 40, 60 and 80 m, the critical merging distances are 50, 70, 90 and 110 m, respectively. Thus, the relationship between the critical merging distance of (3 3) array fires and the tank diameter is given by the following relationship: d cr/d=9.1d (2) (d=40 m) (d=48 m) (d=60 m) (d=74 m) (a) Graphics of HRR distribution (d=40 m) (d=48 m) (d=60 m) (d=74 m) (b) Graphics of oxygen distribution in the vertical central plane Figure 8. Merging profiles of (3 3) n-heptane flames D=40 m, with variation of inter-tank distance. (d=70 m) (d=80 m) (d=90 m) (d=110 m) Figure 9. Plan view of fuel distributions of (3 3) fires, D=60 m (graphics at h=d). Whirling behavior of (3 3) fires in a channel with four gaps at the corners Fig. 10 shows the side view and plan view of whirling profiles of (3 3) fires in a channel with X c=240 m, Y c=1400 m and G=24 m, for D=40 m. In the center of the whirling flame, the fuel is very rich near the bottom and the oxygen is very poor, as seen in Fig. 10(c). Therefore almost no combustion happens in the bottom center region of the whirling flame, as seen in Figs. 10(b) and 10(e), i.e. the combustion 468

7 Part II Fire is limited to the whirling flame surface, a very thin region like a skin, surrounded by a rich oxygen concentration. Large amounts of fuel evaporate in the center of an oil tank, but rise upward without burning because the oxygen is insufficient in the center, and thus a long whirling flame is generated. These profiles for (3 3) fires are very similar to those of single fires reported in the previous study [21]. The time averaged rotational wind speed shown in Fig. 10(d) is 1.05 rad/s. Therefore the whirling motion is about 0.17 Hz for the (3 3) array with array length L=160 m. The whirling motion shown in Fig. 10 for L=80 m is about 0.24 Hz. The rotational cycle (f) of a single whirling fire vs. the array length (L) is shown in Fig. 11 and the relationship is given by the following equations: f = 2.11L (3 3 fire), (3) f = 2.72D (single fire). (4) Both relationships are almost proportional to the inverse of square root of the tank diameter (D) or the array length (L). (d) velocity (plan view at h=l) (a) HRR (b) HRR (c) fuel (e) HRR (plan view at h=l) Figure 10. Side view and plan view of whirling profiles of (3 3) fires in a channel with Xc=240 m, Yc=1400 m and G=24 m (D=40 m, d=60 m, L=160 m) (a):three dimensional graphics, (b) and (c): two dimensional graphics in the central vertical plane. The dimensionless flame lengths (L F/L) are shown in Fig. 12 as a function of dimensionless inter-tank distance, for whirling and free burning fires of D=20 m and D=40 m. Compared with the flame lengths shown in Fig. 7 (with no whirling motion), the whirling flame has very large values, exceeding 1000 m. The ratio of dimensionless flame length for whirling flames to that of free burning flames is about 5:1. The maximum temperature in the whirling fires exceeds 1500 K. In some cases, sudden explosive combustion causes instability in the whirling flame. Such cases are extremely dangerous for firefighters. For D=40 m, the heat release rates in whirling conditions are about 3 to 4 times larger than those in free burning conditions. The maximum heat release rate is at the dimensionless inter-tank distance of d/d=1.7 for whirling cases and at 2.0 for free burning cases. Note that many oil tanks are constructed with a separation of space similar to these distances, which corresponds to the maximum heat release rate of merging fires. 469

8 Proceedings of the Eighth International Seminar on Fire and Explosion Hazards (ISFEH8) Figure 11. Whirling frequency vs. tank diameter or (3 3) array length. Figure 12. Dimensionless flame length of (3 3) fires vs. dimensionless inter-tank distance, for whirling and free burning fires of D=20 m and D=40 m. Fig. 13 shows the whirling profiles of (3 3) arrayed fires with a large inter-tank distance (D=40 m and d=200 m). The channel dimensions are X c=560 m, Y c=800 m and G=40 m. All the flames are whirling but leaning toward the ground. The rotational velocity at about 80 m/s or 2.1 rad/s is much higher than that of a single fire. Velocities in the center of the (3 3) array are examined as a function of height (h), with variation of inter-tank distance. At heights lower than h/d=15, the velocity increases with the dimensionless height, but at h/d=17, the velocity remains almost constant. 3 3 fires t=83.7s (a) HRR (side view) (b) Velocity (plan view) (c) Temperature (plan view) Figure 13. Whirling profiles of (3 3) fires in a channel with Xc=560 m and Yc=800 m (D=40 m, d=200 m, G=40 m). A method to prevent fire whirl generation If the phenomena mentioned above really happen, they would be extremely dangerous for firefighting. Therefore, it is important to mitigate the damage produced by fire whirls and also to prevent or terminate fire whirls. Herein we examine one method for preventing the generation of fire whirls. A simulation example for a channel with four corner gaps (X c=320 m, Y c=800 m and G=28 m) is presented in Fig. 14. We have also examined another case to prevent a fire whirl for single fire [21]. Fig. 14(a) shows the schematics for preventing fire whirl generation around a huge oil tank. A barrier of height h=80 m, width w=280 m and thickness 1 m is located across the center of the (3 3) arrayed oil tanks with D=40 m and d=100 m. As shown in Figs. 14(b), (c) and (d), which show the distribution of HRR (side view), HRR (top view) and temperature, the rotational flow of the fire whirl is blocked by the barrier, and the turbulent flow becomes not whirling. Nevertheless, the barrier is too big and not practical. The identification of more practical ways to prevent fire whirl generation remains to be the effort of future work. 470

9 Part II Fire (a) protection barrier (b) HRR (side view) (c) HRR (plan view) (d) temperature (plan view) Figure 14. Effect of fire whirl protection barrier with dimensions of w=280 m and h=80 m (D=40 m, d=100 m, G=24 m). CONCLUSIONS In this work, using the fire simulation software FDS, fire whirls were generated in a vertically tall channel with four corner gaps, thereby the combustion behavior of fire whirls in huge oil tanks was numerically investigated. Stable fire whirls were produced and velocities and whirling flame lengths of single and (3 3) array fires of n-heptane were examined. It was found that the velocity of whirling flames is about 1.3 times larger than that of free burning flames. The single whirling flame length can reach a height about 10 times the oil tank diameter. The critical merging distance of (3 3) array fires and the tank diameter is correlated by d cr/d=9.1d The whirling flame lengths of (3 3) arrayed fires are 5 times longer than those of free burning fires. In single whirling fires, the radiative heat flux on the fuel surface reaches a maximum in the center of the tank, which induces a large amount of fuel evaporation in the center, however, the fuel vapors move upward without combustion due to insufficient oxygen. Rotational cycles of whirling flames of single and (3 3) array fires are almost proportional to the inverse of square root of the tank diameter or the array length; that is f= 2.11L for 3 3 fire and f= 2.72D for single fire. Further experiments and more precise simulations using smaller grids are needed, since the numerical predictions are highly affected by the grid size. However, if the phenomena mentioned above really happen, firefighters would face extreme danger. Therefore, a method to prevent fire whirl generation is preliminarily examined, by using a barrier located across the center of the arrayed oil tanks. The results show that by this means the fire whirl generation can be prevented. However this methods requires a large size barrier, and so more practical ways to prevent fire whirl generation should be further investigated. ACKNOWLEDGMENTS This research is funded by the National Key Research and Development Plan (No. 2016YFC ) and the National Natural Science Foundation of China (No ). Naian Liu was supported by the Fundamental Research Funds for the Central Universities (No.WK ). REFERENCES 1. Haasl, D. F., Roberts, N. H., Vesely, W. E., and Goldberg, F. F. U.S. Nuclear Regulatory Commission Fault Tree Handbook (NUREG-0492), Oil Tanks Damaged in Hokkaido Earthquakes, The Japan Times News, Dec. 25, Persson, H., and Lönnermark, A. Tank Fires, Review of Fire Incidents , BRANDFORSK Project , SP Fire Technology, SP REPORT,14, Lois, E., and Switchenbank, J. Fire Hazards in Oil Tank Arrays in a Wind, Combustion Institute, Proceedings of the 17th International Symposium, 17(1): , Tank Storage Magazine, Horseshoe Media, 2,

10 Proceedings of the Eighth International Seminar on Fire and Explosion Hazards (ISFEH8) 6. Soma, S., and Saito, K. Reconstruction of Fire Whirls using Scale Models, Combustion and Flame, 86(3): , Satoh, K., and Yang, K. T. Simulations of Swirling Fires Controlled by Channeled Self-Generated Entrainment Flows, In: Hasemi, Y. (Ed.), Fire Safety Science Proceedings of the fifth International Symposium, , Farouk, B., McGrattan, K. B., and Rehm, R. G. Large Eddy Simulation of Naturally Induced Fire Whirls in a Vertical Square Channel with Corner Gaps, International Mechanical Engineering Congress and Exposition (IMECE) Proceedings, 6-10, Matsuyama, K., Ishikawa, N., Tanaka, S., Tanaka, F., Ohmiya, Y., and Hayashi, Y. Experimental and Numerical Studies on Fire Whirls, Fire Safety Science Digital Archive AOFST Symposiums, Liu, N. A., Liu, Q., Lozano, J. S., Shu, L. F., Zhang, L. H., Zhu, J. P., Deng, Z. H., and Satoh, K. Global Burning Rate of Square Fire Arrays: Experimental Correlation and Interpretation, Proceedings of the Combustion Institute, 32(2): , Lei, J., Liu, N. A., and Satoh, K. Buoyant Pool Fires under Imposed Circulations before the Formation of Fire Whirls, Proceedings of the Combustion Institute, 35(3): , Yu, H. Y., Guo, S., Peng, M. J., Li, Q. W., Ruan, J. F., Wan, W., and Chen, C. Study on the Influence of Airinlet Width on Fire Whirls Combustion Characteristic, Procedia Engineering, 9th Asia-Oceania Symposium on Fire Science and Technology, 62: , Su, S. C., Wang, L., Nie, Y. H., and Gu, X. Fire Whirl and its Harmfulness Analysis in the Numerical Simulation of Fire in a Ship Engine-Room, Shipbuilding of China, 3: , Zhou, K. B., Liu, N. A., Lozano, J. S., Shan, Y. L., Yao, B., and Satoh, K. Effect of Flow Circulation on Combustion Dynamics of Fire Whirl, Proceedings of the Combustion Institute, 34(2): , Satoh, K., Shinohara, M., and Yang, K. T. Experimental Observations and Analysis of Square Arrays Equidistant Multiple Fires, International Association for Fire Safety Science, Proceedings of the 3th Asia- Oceania Fire Safety, , Satoh, K., Yang, K. T., and Kuwahara, K. Comparison between Experiments and Numerical Simulations of Fire Whirls due to a Single Flame in a Vertical Square Channel with Symmetrical Corner Gaps, Report of NRIFD, 92: , Satoh, K., Liu, N. A., Zhu, J. P., and Yang, K. T. Experiments and Analysis of Interaction among Multiple Fires in Equidistant Fire Arrays, Proceedings of 2005 ASME/HTD, San Francisco, California, HT , Satoh, K., Liu, N. A., Liu, Q., and Yang, K. T. Numerical and Experimental Study of Fire Whirl Generated in Square Array Fires Placed in Cross Wind, Proceedings of IMECE2008, Boston, Massachusetts, USA, IMECE , Satoh, K., Liu, N. A., Zhou, K. B., and Xie, X. D. CFD Study of Termination of Fire Whirls in Urban Fires, Procedia Engineering, The 9th Asia-Oceania Symposium on Fire Science and Technology, 62: , Satoh, K., Liu, N. A., Xie, X. D., Zhou, K. B., Chen, H. X., Wu, J. M., Lei, J., and Lozano, J. S. CFD Study of Huge Oil Depot Fires, Generation of Fire Merging and Fire Whirl in (7 7) Arrayed Oil Tanks, In: Spearpoint, M. (Ed.), Fire Safety Science Proceedings of the Tenth International Symposium, 11: , Satoh, K., Liu, N. A., Xie, X. D., and Gao, W. CFD Study of a Fire Whirl of Huge Oil Tank-Burning Rate, Flame Length, Distributions of Fuel and Oxygen in a Fire Whirl, Proceedings of 2014 IMECE, Montreal, Canada, IMECE , McGrattan, K. B., Baum, H. R., Rehm, R. G., Hamins, A., and Forney, G. P. Fire Dynamics Simulator: Technical Reference Guide, Technical Report NISTIR 6467, National Institute of Standards and Technology, McGrattan, K., Hostikka, S., McDermott, R., Floyd, J., Weinschenk, C., and Overholt, K. Fire Dynamics Simulator Userʼs Guide, NIST Special Publication 1019, National Institute of Standards and Technology, Baum, H. R., and McGrattan, K. B. Simulation of Oil Tank Fires, International Interflam Conference, 8th Proceedings of Interflam, , Bounagui, A., Benichou, N., McCartney, C., and Kashef, A. Optimizing the Grid Size used in CFD Simulation to Evaluate Fire Safety in Houses-Part I-Basement Fires, IRC Research Report 149, National Research Council Canada, Zhang, H. R., and Yu, Y. A Guidance to Grid Size Design for CFD Numerical Simulation of Hypersonic Flows, 7th Asian-Pacific Conference on Aerospace Technology and Science, Procedia Engineering, 67:

11 Part II Fire 187, Blinov, V. I., and Khudyakov, G. N. Diffusion Burning of Liquids, Akademii Nauk, SSSR, Moscow, Translated into English by US Army Engineer Research and Development Laboratories, Hamins, A., Yang, J. C., and Kashiwagi, T. A Global Model for Predicting the Burning Rates of Liquid Pool Fires, NISTIR 6318, National Institute of Standards and Technology,