Supercavitation phenomenon research of projectiles passing through density change area

Abstract

The past research on the supercavity flow mostly focused on the homogeneous fluid medium, ignoring the influence of the sudden change of the medium density. We present results from numerical study of moving projectile passing density change zone, both from low-density zone to high-density zone and from high-density to low-density. Particular attention is given to the cavity variation when projectile voyaging through different liquid density areas. And the influence of the cavitation number on the cavity variation is also studied. Research results show that there is a ‘diameter shrinkage’ phenomenon when the projectile moving pass the density jump area. The location of ‘diameter shrinkage’ is relative to the density change model: moving from high density side to low, it appears at the interface of liquids; while moving from low density side to high side, it occurs at low density side not the interface. And the degree of ‘necking’ have something to do with the density difference of two sides. However the effect of cavitation number is much complex, the ‘necking’ phenomenon at the interface showed disorder maybe due to the sample limit, but the re-development of the cavity after passing through the interface showing obvious regularity with the cavitation number.

Influence of Periodic Disturbance Incoming Flow on the Supercavitation Phenomenon

“…Zhan et al studied the influence of lateral flow on supercavitation and concluded that the cavity morphology is symmetrical in the absence of lateral flow and asymmetrical in the presence of lateral flow, with the cavity morphology increasing with the velocity . Fan et al studied the change in supercavitation when the projectile passes through different density regions and found that the diameter contraction of the projectile occurs through different density regions and in different locations and is related to the density degree . Zhan et al studied the influence of different wave phases and heights on the supercavitation flow field and found that the wave phases and height affect the resistance of supercavitation .…”

“… 18 Fan et al studied the change in supercavitation when the projectile passes through different density regions and found that the diameter contraction of the projectile occurs through different density regions and in different locations and is related to the density degree. 19 Zhan et al studied the influence of different wave phases and heights on the supercavitation flow field and found that the wave phases and height affect the resistance of supercavitation. 20 Jiang et al carried out experimental research on ventilated supercavitation injected with high-temperature gas, concluded that the length of the supercavitation would increase under the injection of high-temperature gas, and obtained a theoretical model of the thermodynamic effects.…”

Numerical research of lateral flow influence on supercavitating flow

“…7,8 studied the influence of free liquid on the cavity shape of the moving body and the flow field in the cavity through experiments and numerical methods. 9,10 used numerical methods to study the characteristics of supercavitation flow under complex environmental interference. The study obtained the law of the influence of environmental factors, such as density mutations and seabed obstacles, on the development of supercavitation morphology.…”

Influence Rule of Projectile Density on the Characteristics of High-Speed Water-Entry Cavity

“…In studying the problem of torpedo failure, Gilbarg and Anderson (1948) experimentally analyzed how different factors depend on the waterentry cavity, and found that air density has a significant effect on the closing time of the cavity surface near the point of water entry. In recent years, some researchers have studied the cavity changes of projectiles when the projectiles navigate in regions of different liquid density (Fan et al 2019). Some researchers have also proved that density is an important factor in materials and has a certain influence on the range and power of projectile ， both experimentally and theoretically (Forouzani et al 2018;Sorensen et al 2008;Wang et al 2020;Zhang et al 2021).…”