Similarity of scaled-down tests of water entry slamming considering the effects of atmospheric pressure and density

作者：Shiqi Fan, Xiongliang Yao, Guihui Ma, Jiaxing Lu, C.W. Lu, J. M. Chen, Linlin Wang, Jia-Ning Ji · 发表于：Physics of Fluids · 年份：2024 · DOI：10.1063/5.0237940 · 被引用次数：14 · 研究领域：Fluid Dynamics Simulations and Interactions、Fluid Dynamics and Heat Transfer、Ship Hydrodynamics and Maneuverability

The water entry cavity and load characteristics obtained through scaled-down tests are correlated with the atmospheric pressure and density at the free surface. The evaluation of the influence of the cavitation number and atmospheric density coefficient is highly essential for scale tests to improve the prototype prediction accuracy. Focusing on the similarity criterion simulations and load prediction of the scaled-down tests, this study conducts the simulation tests of the water entry characteristics of the scaled-down model under different environments: normal pressure, reduced pressure, and reduced pressure and heavy gas replacement. Moreover, the influence of the cavitation number and atmospheric density coefficient on the multiphase flow, slamming load, and air cushion effect is discussed. The “air cushion effect” is formed at the top of the vehicle during water entry process, which affects the peak narrow pulse width slamming load. Furthermore, the “air cushion” experiences expansion–stability–rupture–escape with increasing water invasion depth. As the atmospheric pressure decreases, the gas tends to thin and the retention inertia weakens. The decrease in the “air cushion” buffering capacity leads to the increase in the slamming load and the expansion of the cavity scale formed by the liquid. Excessive simulation of the dynamic pressure results in the delayed closure of the cavity surface and the slow fall of the water curtain. As the atmospheric density increases, the ...