旋涡自吸泵流致噪声模拟及降噪

以比转数为15.9的旋涡自吸泵为研究对象,结合CFX和LMS Virtual Lab中的Acoustic Harmonic BEM模块对旋涡自吸泵内流压力脉动和流致噪声进行仿真研究,旨在降噪优化.首先采用RNG k-ε湍流模型对旋涡自吸泵0.4Q_d,0.6Q_d,Q_d这3个工况下的内部流场分别进行定常、非定常求解,捕捉蜗壳壁面以及进出口管道壁面的压力脉动数据,并以cgns文件导入Acoustic Harmonic BEM模块进行声场计算,求解旋涡自吸泵内部的声压级大小及其分布特性.结合内流压力脉动与声场计算结果综合分析可得:蜗壳隔舌与叶轮的间隙内的压力脉动是产生流致噪声的主要因素.为了降低旋涡自吸泵内部流致噪声,借鉴涡轮叶片锯齿尾缘结构,优化叶片以降低间隙内流压力脉动.通过流场和声场的数值模拟的对比分析发现:优化泵隔舌间隙处压力脉动幅度在设计工况下最大降低20.0%,在小流量工况下最大降低26.6%;较之原模型,设计工况下改进型泵进、出口管道监测点的声压级分别降低1.01,1.03 dB;小流量工况下,进、出口管道声压级最大幅值分别降低8.57,2.65 dB.

Flow-induced noise and noise reduction of self-priming vortex pump

A research on the internal sound field characteristics was conducted in order to reduce the running noise of self-priming vortex pump. The CFX software and Acoustic Harmonic BEM of LMS Virtual Lab software were combined to study the internal pressure pulsation and the noise generated. Firstly, the pressure fluctuations of self-priming vortex at 0.4 Q_d, 0.6 Q_d and Q_d were obtained from the unsteady simulations with RNG k-ε turbulence model in the CFX software. Secondly, pressure fluctuations data were extracted and input into the LMS Virtual Lab software. Finally, the SPL of the pump discharge and the internal sound pressure distributions at different flows were obtained by acoustic field calculations. From the analysis of the CFD results and acoustic field calculations, it is concluded that the rotor-tongue interaction is the main cause of the noise. Results from the sawtooth structures on the trailing edge of turbine blade for reducing pressure pulsation, the CFD and acoustic field calculations show that the maximum amplitude of pressure pulsation decreases, by 20.0 % and 26.6 % respectively at Q_d and low-flow rate. The SPL at Q_d, decreases by 1.01 dB and 1.03 dB respectively in the inlet and outlet pipes. The SPL at low-flow rate, decreases by 8.57 dB and 2.65 dB respectively in the inlet and outlet pipes.