特定热层温度下入射角对前驱波特性的影响OA北大核心CSTPCD

An intense explosion in the air releases heat radiation to form a thermal layer on the earth's surface,and the shock wave propagates faster when it enters the thermal layer,forming a precursor wave. The incidence angle is an important factor affecting the characteristics of the precursor wave,but at present,most of the related work depends on theoretical derivation,and the experimental research is few. The influence of the incident angle on the precursor wave formation at 300 ℃ is studied using an explosion wave simulation shock tube platform. A thick iron plate is heated to 300 ℃ and fixed in the shock tube test section,the surface of which produces a thermal layer of 1 cm thick. The interaction between the shock wave generated by the shock tube and the thermal layer is captured by a high-speed camera. The influence of different incident angles on the precursor wave is studied. A numerical simulation model is established based on the experimental configuration. First,a complete axial symmetric shock tube model is established,and a data monitoring point is set at the position corresponding to the pressure measurement point in the model. Then,a plane model is built. The data of total pressure,static pressure,and total temperature calculated in the first step are the input,and the cloud diagram and pressure curve at the measuring point of the model are the output. The results show that the critical angle range of the precursor wave is consistent with the theoretical results. The greater the angle of incidence,the greater the distance of the precursor wave over the Mach stem,and the earlier the arrival time. The precursor wave will lead to a decrease in the peak overpressure,and as the incident angle increases,the decrease degree of overpressure peak increases first and then decreases. Overall,the peak dynamic pressure increases with the incident angle. When the incident angle reaches a certain threshold,the peak dynamic pressure begins to fluctuate in a certain range,the reason is that the peak arrival time of airflow density and particle velocity are different. The increase degree of dynamic pressure impulse increases with the increase of incident angle.