球阀阀口气穴流场的数值模拟与实验研究

Numerical and Experimental Investigation of Cavitating Flow in Oil Hydraulic Ball Valve

将 RNG k-ε湍流模式与多相流技术相结合 ,对球阀阀口的三维气穴流场进行了数值模拟 ,计算了小球在对称位置与非对称位置的气穴流场。运用高速摄像机观察了阀口附近的气穴现象 ,与模拟结果比较 ,相当吻合。对球阀有无气穴现象分别进行了噪声测试和频谱分析。实验结果表明阀口气穴现象以 2 5 0 0 Hz的频率周期性地发生 ,小球及小球弹性系统在轴向的固有频率远小于 2 5 0 0 Hz,而且频率 2 5 0 0 Hz对应的噪声级很高。比较了数值模拟得到的对称与非对称气穴区域与实验观察到的气穴云变化。进一步预测阀的横向振动使得气穴现象周期性发生。

A three-dimensional cavitating flow issuing from the orifice of a ball valve was numerically investigated by using the combination of RNG k- ε turbulence model and multiphase flow model. The cavitation region was predicted for axisymmetric and non-axisymmetric case when the ball moves to one side. Flow visualization experiment was conducted to capture cavitation images near the orifice of the ball valve using high-speed video camera. The predicted and observed cavitation region agrees well. Furthermore, the noise spectrums of the ball valve in cavitation and non-cavitation cases are measured. The results show that the cavitation around the orifice occurs periodically with a very high frequency of 2500 Hz and the noise level is high at 2500Hz. The natural frequency of the ball in the axial direction and something is far from 2500Hz. The predicted cavitation region for axisymmetric and non-axisymmetric case was compared with experimentally visualized cavitation image. It was expected that the ball vibrates in the lateral direction and cavitation occurs frequently.