scholarly journals Blind Simulation of Periodic Pressure and Burning Rate Instabilities in the Event of a Pool Fire in a Confined and Mechanically Ventilated Compartment

2016 ◽  
Vol 188 (4-5) ◽  
pp. 504-515 ◽  
Author(s):  
T. Beji ◽  
B. Merci
Author(s):  
Quanyi Liu ◽  
Wei Yao ◽  
Jiusheng Yin ◽  
Rui Yang ◽  
Hui Zhang

Airplane as one of the important transport vehicles in our life, its safety problem related to in-flight fire has attracted a wide-spread attention. The combustion behavior of the cabin fire in flight shows some special characteristics because of the high-altitude environment with low-pressure and low oxygen concentration. A low-pressure chamber of size 2 m×3 m×2 m has been built to simulate high-altitude environments, where multiple static pressures for pool fire tests can be configured in the range between standard atmospheric pressure 101.3KPa and 30KPa. Two different sizes of pool fires were tested. Then corresponding modeling were conducted by a LES code FDS V5.5 to examine the mechanism of pressure effect on the n-Heptane pool fire behavior. The burning of liquid fuel was modeled by a Clausius-Clapeyron relation based liquid pyrolysis model. The modeling data was validated against the experimental measurements. The mass burning rate of free-burning pool fire decreases with the decreasing of pressure, which was observed from the modeling to be due to the reduction of flame heat feedback to the fuel surface. Under low pressure, the fire plume temperature increases for the same burning rate. The mechanism of pressure effect on fire behavior was analyzed based on the modeling data.


Fuel ◽  
2020 ◽  
Vol 269 ◽  
pp. 117467 ◽  
Author(s):  
Xiangliang Tian ◽  
Chang Liu ◽  
Maohua Zhong ◽  
Congling Shi

2016 ◽  
Vol 34 (4) ◽  
pp. 323-334 ◽  
Author(s):  
Chunming Jiang ◽  
Yuntao Li ◽  
Hong Huang ◽  
Jinlong Zhao ◽  
Zheng Wang ◽  
...  

2019 ◽  
pp. 266-266
Author(s):  
Hing Hung ◽  
Shousuo Han ◽  
Wan Chow ◽  
Cheuk Chow

The fire whirl generated by burning a pool fire in a vertical shaft with a single corner gap of appropriate width was studied using a high-speed camera. A 7-cm diameter pool propanol fire with heat release rate 1.6 kW in free space was burnt inside a 145-cm tall vertical shaft model with gap widths lying between 2 cm and 16 cm. The flame height was between 0.25 m and 0.85 m for different gap widths. Photographs taken using a high-speed camera at critical times of swirling motion development were used to compare with those taken using a normal camera. From the experimental observations on flame swirling by a high-speed camera, stages for generating the fire whirl were identified much more accurately. Two flame vortex tubes moving over the horizontal burning surface of the liquid pool were observed. Based on these observations a set of more detailed schematic diagrams on the swirling motion was constructed. From the observed flame heights under different gap widths and using three assumptions on the variation of air entrainment velocity with height, an empirical expression relating the burning rate with flame height and the corner gap width was derived from the observation with high-speed camera. The correlation expression of the burning rate of the pool fire obtained would be useful in fire safety design in vertical shafts of tall buildings.


Author(s):  
Nathaniel Sauer ◽  
Xiaoyue Pi ◽  
Kemal Arsava ◽  
Ali Rangwala

ABSTRACT The focus of this study is to quantify the controlling mechanisms, which increases the burning rate of a pool fire using a Flame RefluxerTM. Part of the Flame RefluxerTM, is exposed to the fire and is heated up transferring heat to the fuel pool layer to which it extends. This enhances the conventional heat transfer that occurs only through the pool surface by transferring the heat from a fire to an in-depth layer of the liquid. Both sensible heat and heat of vaporization are supplied at increased rates by the submerged material. As an additional important effect, nucleate boiling onsets at the surface of the inserted material that generates bubbles of fuel vapor. These bubbles are transported to the surface of the pool, where they burst and release the v0061por to the gas-phase. While doing so, additional processes such as formation of micron-sized droplets or small jets of liquid fuel from the break point occur. This phenomenon causes additional fuel in liquid phase transported to the gas-phase, where they vaporize, ignite and burn in heterogeneous mode. Therefore, the processes involved in FR occur in three steps; enhancement of heat transfer to the liquid causing nucleate boiling, formation of bubbles and their transport, and dynamics of bubble breakage at the pool surface causing transfer of liquid fuel in the form of tiny droplets or jets towards the gas-phase. This study analyzes the influence of bubbles on the burning behavior of a pool fire using a simple experiment involving burning ethanol as a fuel. Ethanol is used due to its transparency and hence bubble behavior is easily observable on the heater surface. A 5cm x 5cm glass enclosure constantly replenished with ethanol serves as the burning pool. A solid aluminum block (8.8 cm tall x 3.6 cm wide x 1.2 cm thick) is placed in the flame to act as the Flame RefluxerTM. Bubble counts and burning rate measurements indicate the influence of the bubbles on the overall burning rate of the liquid pool.


2021 ◽  
Vol 7 ◽  
Author(s):  
Juan J. Cruz ◽  
Ignacio Verdugo ◽  
Nicolás Gutiérrez-Cáceres ◽  
Felipe Escudero ◽  
Rodrigo Demarco ◽  
...  

The main characteristics of pool fire flames are flame height, air entrainment, pulsation of the flame, formation and properties of soot particles, mass burning rate, radiation feedback to the pool surface, and the amount of pollutants including soot released to the environment. In this type of buoyancy controlled flames, the soot content produced and their subsequent thermal radiation feedback to the pool surface are key to determine the self-sustainability of the flame, their mass burning rate and the heat release rate. The accurate characterization of these flames is an involved task, specially for modelers due to the difficulty of imposing adequate boundary conditions. For this reason, efforts are being made to design experimental campaigns with well-controlled conditions for their reliable repeatability, reproducibility and replicability. In this work, we characterized the production of soot in a surrogate pool fire. This is emulated by a bench-scale porous burner fueled with pure ethylene burning in still air. The flame stability was characterized with high temporal and spatial resolution by using a CMOS camera and a fast photodiode. The results show that the flame exhibit a time-varying propagation behavior with a periodic separation of the reactive zone. Soot volume fraction distributions were measured at nine locations along the flame centerline from 20 to 100 mm above the burner exit using the auto-compensating laser-induced incandescence (AC-LII) technique. The mean, standard deviation and probability density function of soot volume fraction were determined. Soot volume fraction presents an increasing tendency with the height above the burner, in spite of a local decrease at 90 mm which is approximately the position separating the lower and attached portion of the flame from the higher more intermittent one. The results of this work provide a valuable data set for validating soot production models in pool fire configurations.


Author(s):  
S. Sudheer ◽  
S. V. Prabhu

Characterization of pool fires in the presence of cylindrical containers is highly relevant for various applications. A cylindrical container is idealized as a circular pipe packed with insulating material inside. Open pool fire experiments are conducted with a cylindrical container located at the center. The pool fire diameters considered were 0.5 m, 0.7 m and 1.0 m with diesel as the fuel. The cylindrical containers are made of stainless steel 304L. The outer diameters of the pipes are 114 mm, 168 mm and of thickness 8.6 mm, 7.1 mm respectively. The effect of blockage ratio on the mass burning rate for vertical and horizontal orientations of 168 mm cylindrical container is studied. It is observed that there is no significant change in mass burning rate due to the blockage effect. Temperatures are measured at various locations inside the pipes and at the center of the insulation. It is observed that the temperatures along a plane perpendicular to the axis are uniform when the pipes are vertically oriented. IHCP 1D code is applied to estimate the incident heat flux on to the bodies when immersed in open pool fires with different orientations.


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