翼型空化绕流数值研究

空化是发生在流体机械上的复杂过程，理论研究遇到很大困难。本文引入合适的空化数值模型，将空腔界面近似为自由面，用界面构造精度较高的流体体积方法求解空腔位置，通过直接求解原始变量的NavuerStokes方程，数值模拟了无界域中空化在翼型上发生、发展和脱落的周期过程；并分析了空化产生对翼型表面的压力分布、翼型收到的阻力和升力的影响。结果表明，空化出现在翼型上表面；由于空化的产生，翼型表面压力分布不稳定，导致升力、阻力和流场压力出现波动，这是实际中产生噪声和损失的主要原因。

Numerical Study of Cavity Flow around a Hydrofoil

There are many difficulties in theoretically studying cavitation, a complex phenomenon occurring in fluid machinery. Based on an appropriate cavity model, cavity flow around a hydrofoil in an unbounded domain was numerically studied through Navier-Stokes equations and Volume of Fluid (VOF) method to construct cavity interfaces more accurately. The period-like phenomen, incipience, development, and shedding of cavity, were demonstrated; furthermore, the cavity effects on coefficients of pressure, drag and lift around the hydrofoil were also numerically analyzed. The results indicated that the cavitation appears on the upper side of the hydrofoil. Due to cavitation, the pressure distribution around the foil is unsteady, the drag and lift forces are randomly changed, which were the main reasons leading to environment noise and mechanical loss.