The Mass Burning Rate of n-Heptane Pool Fire Under Dynamic Pressure

Fire safety is critical for safety of airplane operation. During an emergency landing, airplane goes through dramatic external pressure change from cruise altitude to sea level, considering the impact caused by low pressure atmosphere. The objective of this work is to examine the effect of dynamic pressure on the behavior of a horizontally burning diffusion flame over a pool fuel surface based on experimental approach. The experiments were conducted in a large-scale altitude chamber of size 2 m × 3 m × 4.65 m. The pressure rise process was examined under different dynamic pressures from respectively 38 kPa, 64 kPa and 75 kPa to 90 kPa with various pressure rise rates of 100 Pa/s, 150 Pa/s, 200 Pa/s, 250 Pa/s and 300 Pa/s, which is to simulate the airplane landing process from different altitudes. The whole system of the altitude chamber is of unique capability that the pressure in the chamber can be exactly controlled by a powerful pressure controlling system, and the oxygen concentration can maintain at the level about 20%, which are achieved through controlling inlet air flow for oxygen level and outlet gas flow for pressure (static or dynamic) level. A round steel fuel pans of 34 cm in diameter and 15 cm in height were chosen for the pool fire tests. The fuel pan was filled with 99% pure liquid n-Heptane. Cold water is added beneath the fuel layer to cool the pan and minimize the temperature rise in the fuel. Parameters such as mass, mass burning rate, chamber pressure were measured. The results of those tests demonstrated the significant impact to fire behaviors caused by high altitude or low pressure atmosphere.