Quanyi Liu

Experiments investigating fuel spread behaviors for continuous spill fires on fireproof glass

A series of large-scale spill fire experiments with continuous discharge on a rectangular fireproof glass sheet were conducted, to better understand spill fire spread behaviors on land. JP-5 and heptane were selected as the fuels, with discharge rates varying from 0.93 to 6.82 L/min. Results show that the spread process can be divided into five phases: spread burning, shrink burning, quasi-steady burning, boiling burning, and extinguished. Not all of the burning phases appear during the process, which is related to the burning scale and the type of fuel. The burning rate of the quasi-steady burning phase is smaller than that of pool fires under the same burning scale. The ratio of the spill fire burning rate to the pool fire burning rate is close to 0.54 for JP-5 and 0.78 for heptane. In addition, we observed that the burning areas expand quickly at the beginning of a boiling burning phase and that the disturbance or entrainment of the flames becomes violent at the beginning of this phase. In the spread process, the empirical correlation between the maximum burning areas ( A max ) and the discharge rate ( Q · in ) is A max = 0 . 057 ( Q · in / W ) 0 . 875 (W is the width of glass) for JP-5, and A max = 0 . 13 ( Q · in / W ) 0 . 61 for Heptane. The ratio of maximum area to quasi-steady area is approximately 1.46 in the experiments.

Modeling on n-Heptane Pool Fire Behavior in an Altitude Chamber

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.Copyright

Solid Fuel Fire Behavior Under Fixed Pressure in a Low-Pressure Chamber

To comprehensively reveal the difference of solid fuel fire characteristics at different altitudes, fire experiments of cardboard boxes at multiple static pressures with two configurations filled with shredded office paper were conducted in a low-pressure chamber. The measured parameters are mass burning rate, radiative heat flux, oxygen concentration and heat release rate (HRR) etc. The mass burning rate divided by fire base dimension m/D is correlated against the production of pressure-squared times length-cubed (P2L3) to the power of 0.29 based on current cardboard boxes fire test data. HRR of two boxes fire tests are higher than that of one box fire tests under fixed pressures. However, there are a higher peak of HRR under a fixed higher pressure for one-box fire tests while a lower peak of HRR under a higher pressure for two-box fire tests. The HRR would decrease sharply after reaching the peak.Copyright

Experiment Study of Cardboard Box Fire Behavior Under Dynamic Pressure in an Altitude Chamber

Fires recently at low ambient pressure such as cruising airplane and high altitude airport have attracted great attention. Understanding fire behavior under low pressure is one of important fundamental problems for fire safety engineering design in forementioned environment. Observation of cardboard fires under dynamic pressure is of significant meaning to study continuous variation of fire behaviors of solid fuel during depressurization.An altitude chamber of 2×3×4.65 m3 with a powerful pressure controlling system was designed to observe fire behavior of cardboard fires under dynamic pressure. In the chamber, two configurations of cardboard boxes filled with shredded office paper were tested under dynamic pressures at descent rates: 5.46kPa/min, 10.92kPa/min, and 19.68kPa/min for both configurations. Measured parameters in this study include flame temperature, radiative heat flux, and mass burning rate. The measurement data were analyzed to reveal depressurization effect on fire behavior.Copyright

N-Heptane Pool Fire Behavior in a Controlled Oxygen and Low-Pressure Environment

Fires at high altitude airports have attracted a lot of attention. Such fires show some special characteristics because of the coupling impact of low pressure and low oxygen levels. Some experiments, which were conducted recently at high altitude locations, such as Lhasa and in some low pressure chambers, were usually extinguished due to the limited supply of oxygen.In order to reveal the dependence of fire behavior on pressure comprehensively, a low-pressure chamber with ventilation control of 2×3×4.65m3 in volume has been developed and built, which can allow larger scale fire tests to be conducted and simulate more realistic high-altitude environment. In this study, pool fire tests using 20-cm and 30-cm-diameter pans are configured under five different static pressures, e.g. 101kPa, 75kPa, 64kPa, 38kPa and 24kPa. Each test has been repeated three times. The parameters measured include flame temperature, radiative heat flux, and mass loss etc. It is concluded that under lower pressure, mass burning rate is lower, temperature is higher, and height of the flame is higher, which demonstrated that low pressure fire is more dangerous to the buildings at high altitude airports.Copyright

Advancement of Computational Heat Transfer in Fire Research in China

Computational heat transfer became one of the major tools for engineering system design in 1970’s. It has been introduced into Chinese society since 1980’s, especially after Brian Spalding’s first lecture in 1984 in China. As one of Brian’s a few early visiting scholars from China, Professor W. C. Fan has begun his endeavor to expand computational heat transfer to fire research. This paper will first briefly introduce the history of the development of computational modeling with particular applications in fire research — a state funded large project, and then present some representative research work in fire research including recent works on high altitude fire and performance based design.Copyright