A novel FEM-FVM coupled method of evaluating the explosion shock wave of a thermobaric bomb on the internal and external flow characteristics of aircraft

Abstract

The high-temperature and high-pressure shock waves generated after the explosion of a thermobaric bomb have a considerable impact on the aerodynamic characteristics of aircraft. Taking a typical thermoelastic model as the object, the explosion process was calculated by LS-DYNA software. The obtained pressure–time history curve data were written into a UDF function and coupled with Fluent software. At the same time, the afterburning effect of the combustion agent was considered. The influence of the explosion effect on the flow field characteristics of an M6 wing and the inlet of a turboprop engine was evaluated. Thus, an FEM-FVM co-simulation method was established. The results showed that when affected by the explosion shock wave of a thermobaric bomb, the maximum changes in the lift, drag, and pitch moment of an M6 wing in a very short period of time are 29, 13, and 7 times those of the original, respectively, and the effect is mainly reflected in the first shock wave. For the flow field in the intake duct, the total pressure recovery coefficient of the outlet section is reduced by up to 68%, and the distortion rate is increased by up to 325%. This change may even lead to engine surge and shutdown. Moreover, regardless of internal or external flow, the high-temperature airflow after detonation also affects the thermal protection ability of the wing or the inlet profile. All these factors need to be considered comprehensively in the design phase of the aircraft.