半球头模型空化流场非定常特性的数值模拟

为了更好地利用数值方法研究空化流场的非定常特性，结合简化的Rayleigh-Plesset方程，建立了一个新的空化模型。利用新空化模型对半球头水下航行体的空化流场分别进行了定常和非定常的二维轴对称数值模拟研究。新空化模型的成功应用表明，空泡在扩张过程中发生冷凝相变，在收缩过程中发生蒸发相变。由数值模拟与实验现象的比对分析可知，按照空化数大小，空化流场分为3种类型，分别是超空化流场、次生空化流场和弱空化流场，且由于非定常性影响，每种类型的空化流场都对应着不同的模型系数。新空化模型能够成功捕捉空化流场的非定常细节，有助于进一步研究空化机理。

Numerical Study on Unsteady Characteristics of Cavitation Flow Generated from Hemispherical Model

To further study the unsteady characteristics of cavitation flow, a new mathematical cavitation model based on Rayleigh-Plesset equation was given out. Both steady and unsteady cavitation flow generated from hemispherical cylinder were simulated numerically by using the new model in 2D axial symmetrical coordinates. The successful application and validation of the new model show that the condensation occurs when the bubble expands and evaporation happens when the bubble collapses. It can be seen from the analysis of the experiments and the numerical simulations that, according to the cavitation number, the cavitation flow is divided into three types, i.e. supercavitation flow, secondary cavitation flow and weak cavitation flow. Due to the unsteadiness, each type of cavitation flow corresponds to different model coefficients. The new cavitation model can successfully capture the unsteady details of the cavitation flow, and it is helpful to further study the mechanism of cavitation.