方腔涡流运动对压力脉动噪声影响的数值分析

Numerical analysis of a pressure pulse with a vortex around a submerged cavity

为了研究水下方腔内的湍流流动情况,采用k-ε模型和大涡模拟(LES)方法分析了腔内流场的涡旋分布及其发展规律、关键位置的压力脉动特征.运用MATLAB平台对时域下的压力脉动信息进行快速傅里叶变换,得到频域脉动压力级结果,进而讨论了腔内关键压力点的脉动特征.结果表明:压力脉动的峰、谷特征与涡流运动状态具有良好的对应性;方腔不同位置点的压力脉动频率和压力级特征不同,与相应的涡流运动状态密切相关;通过与相同方腔模型脉动声压实验数据的对比表明,在40 Hz以上频率,方腔涡流压力脉动级与实验具有很好的符合度,验证了数值模拟和傅里叶分析方法的可行性和准确性.

The turbulent flow around a submerged cavity was simulated by a computational fluid dynamics（CFD） method with a k-ε model and large eddy simulation（LES）.The generation and development of vortex flow as well as the characteristics of pressure fluctuation in key positions were analyzed.The pressure information in the time mode was changed to the pulse information of the pressure level in the frequency mode through fast Fourier transformation（FFT） in a MATLAB program,and the vortex motions of three key positions were discussed.The results indicate that the characteristics at peak and valley points of the pressure pulse showed a good match with that of the vortex moving.Different positions in the cavity result in different characteristics of the pressure pulse and pressure level,and are closely related to the vortex status.The simulation results also are compared to the measurement data and it shows well agreement on vortex pressure level over frequency 40 Hz.The simulation and Fourier analysis method were demonstrated to be suitable for use in analyzing the cavity flow and vortex noise.