一种弹体入水冲击波阴影成像可视化系统及其试验研究

It is of great practical significance to expand the imaging field for the visualization research of shock wave propagation and dispersion caused by water-entry projectiles in water-filled tank. The shadowgraph technique is suitable for large field experiments, and the visualization of shock waves and disturbances in the flow field is simple and universal. Among them, the direct shadowgraph technique is the simplest, but the lack of reliable point light sources is the bottleneck hindering its development and application. Therefore, based on domestic short-arc xenon lamps a self-made short-arc xenon lamp point light source was designed. According to the principle of shadowgraph, a shadowgraph visualization system of shock waves caused by water-entry projectiles was designed, and its composition and operating principle were introduced in detail. The system had been used to conduct experimental research on high-speed water-entry projectiles. A shadowgraph technique was employed to visualize the shock wave generated by the water-entry projectile in a water-filled tank. Besides, by extracting pixel points from high-speed photos and calibrating the geometric dimensions in the photos, a spatial coordinate system was established to describe the motion of the projectile and shock wave. Simultaneously, the pressure time history curve of shock wave signal was obtained by means of the acquisition equipment of shock wave signal. With the combination of shadowgraphs and shock wave signals, the propagation characteristics of the shock wave produced by the water-entry projectile were analyzed, and they were verified by theoretical calculations. The results show that the reliability and rationality of the visual system of the shock wave generated by the water-entry projectile are demonstrated. After the projectile enters the water at a high speed, the initial shock wave has the highest intensity. As the shock wave propagates, the shock wave intensity gradually decreases, the propagation speed of the underwater shock wave continues to decrease, and the radius of the spherical shock wave gradually increases.