液下泵内部非定常流动及噪声特性

为研究液下泵内部流动的非定常特性及噪声规律,通过采用计算流体动力学软件ANSYS CFX15.0与LMS Virtual.lab声学仿真软件相结合的一种间接混合计算方法,对液下泵内部流场及其声场进行求解.在该计算方法中,对流场进行求解得到监测点的非定常压力脉动,从而获得非稳态的压力脉动频域特性规律;基于声学边界元法,对液下泵蜗壳偶极子内场噪声和叶片偶极子内场噪声进行求解,获得了边界元表面的声压级分布以及典型场点的声压频率曲线.计算结果表明:叶片扫掠过程中与蜗壳隔舌的相互作用产生较大的压力脉动,隔舌附近的噪声是流动噪声的主要噪声源;声压级在叶片通过频率及其谐频时达到极大值,随频率的增大,声压级极大值都呈现衰减状态.研究结果可为液下泵的后续降噪分析提供一定的理论基础.

Unsteady characteristics and noise of internal flowin vertical sump centrifugal pump

The flow and sound field in a vertical sump centrifugal pump were solved by using an indirectly mixed computational method of computational fluid dynamics(CFD)software ANSYS CFX15.0 and acoustics simulation software LMS Virtual.lab to investigate unsteady characteristics and noise pattern of the pump.In this method,firstly,the unsteady pressure pulsations in time domain at a few monitoring points in the flow field were obtained by solving the flow field,thereby the characteristics of these unsteady pressure pulsationsin frequency domain were determined.Based on the acoustic boundary element method,the internal acoustic field of the volute and blade dipoles was solved,the sound pressure level distribution on the surface of boundary elements and the sound pressure frequency curve at typical field points were obtained.The results show that the interaction between sweeping blades and the volute tongue produces a larger pressure pulsation,and the noise near the tongue is the main sound source for the flow borne noise.The sound pressure level reaches the maximum at blade passing frequency and its harmonic frequencies.With increasing frequency,all the maximum sound pressure levels decrease.The results can provide a certain theoretical basis for subsequent analyses of noise reduction issued by vertical sump centrifugal pumps.