Effects of concentration, temperature, ignition energy and relative humidity on the overpressure transients of fuel-air explosion in a medium-scale fuel tank

Experiments were conducted in a 907.5-L fuel tank to investigate the effects of concentration, temperature, ignition energy, and humidity on the explosion overpressure transients of gasoline-air mixture explosions. The results show that the overpressure-time profiles can be roughly divided into four stages: incubation stage, slow acceleration stage, abrupt acceleration stage, descending stage. During the explosion process, intense overpressure oscillation occurred in the fuel tank. Specifically, both the maximum overpressure (p(max)) and the maximum rate of overpressure rise ((dp/dt)(max)) increased firstly and then decreased as the gasoline concentration increased, and the correction between overpressure parameters and gasoline concentration is approximately cubic polynomial. The peak values of p(max) and (dp/dt)(max) were obtained at the concentration of 1.71%. The influence of temperature on p(max) and (dp/dt)(max) was relatively complex, which may result from the vessel volume and the initial gas concentration. Moreover, with the increase of ignition energy, p(max) and (dp/ dt)(max) according to a linear increase trend and a logarithmical increase trend, respectively. With the increase of initial humidity, both p(max )and (dp/dt)(max) showed a linear decrease trend. These results are useful for understanding the explosion characteristics of fuel-air mixtures under various initial conditions in medium-scale fuel tanks.