Experimental study of the mass burning rate in 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. The objective of this work is to examine the effect of dynamic pressure on the behavior of a horizontally burning 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 with different landing speed. The whole system of the altitude chamber is of unique capability that the pressure in the chamber can be exactly controlled, which are achieved through controlling the air inlet rate and the vacuum pumping rate. A round steel fuel pan of 34 cm in diameter were chosen for the pool fire tests. The fuel pan was filled with 99% pure liquid n-Heptane. Parameters such as mass, mass burning rate, chamber pressure were measured. The test results demonstrated the significant impact on fire behaviors caused by high altitude or low pressure atmosphere. The mass burning rate under dynamic pressure increases showed power function growth with the Grashof number, and the exponent factor for all cases is 0.309.