水翼非定常空化流场的数值模拟

Numerical simulation of unsteady cavitating flow on hydrofoil

采用修正的RNGk-ε湍流模型对8°攻角NACA0015水翼的非定常二维空化流场进行数值模拟,分析当空化数分别为1和1.5,对应雷诺数为3×105时绕翼型的非定常流动,得到不同空化数下的非定常空化流场结构及其演化过程的流动特性.计算结果表明,回射流在空泡的形成和发展过程中起着重要的作用.空泡首先出现于水翼的前缘,在其产生的位置形成一个顺时针的漩涡,漩涡沿水翼上表面向下游移动.空泡逐渐长大并脱落,在不同空化数下,空泡脱落的位置不同.空泡形成和发展过程中均伴有压力的波动,大空化数流场的压力波动幅度和频率都明显高于小空化数流场.

The unsteady cavitating flow around an NACA0015 hydrofoil at an angle of attack of 8°was simulated by a modified RNG κ-ε turbulence model with two different cavitation numbers of 1 and 1.5, and the Reynolds number of 3× 10^5. The structure of unsteady cavitating flow was obtained and so were the flow characteristics of its evolution process. Results show that the re-entrant jet plays an important role in the initiation and development process of cavity. The cavity first appears in the leading edge. Then the clockwise vortex developed in the same location moves to downstream along the surface of hydrofoil. The cavity grows up gradually and sheds from the hydrofoil and the shedding locations are different according to the cavitation numbers. The initiation and development process of the cavity accompany the pressure fluctuation. The amplitude and the frequency of pressure fluctuation of cavitating flow with a large cavitation number are obviously greater than that with a smaller eaviation number.