离心泵作透平流体诱发外场噪声特性及贡献分析

摘要

Numerical simulation and test investigation were performed for flow-induced exterior noise characteristics of a centrifugal pump as a turbine (PAT).Under typical flow conditions,dipole sources were obtained using Reynolds-average method.The flow-borne noise and flow-induced structure noise in exterior acoustic field due to impeller and casing dipole sources were solved with FEM/AML.Furthermore,the spectral characteristics of each noise source and their contributions to exterior noise were distinguished.Meanwhile,modal parameters for casing were recognized with modal test.Results showed that the average relative error of natural frequencies between calculation results and test ones is less than 4.60% with the similar modal shapes;the sound pressure at the fifth order blade natural frequency (BNF)is the highest due to the influence of casing structure,and that at the second order BNF takes the second place;the flow-induced structure noise due to casing dipole sources makes the biggest contribution to exterior noise,the flow-borne noise due to casing dipole sources follows and the flow-borne noise due to impeller dipole sources is the least.The results provided a reference for low noise design of similar turbomachineries.%以某离心泵作透平为研究对象，对流体诱发的外场噪声特性进行了数值计算和试验研究。在典型流量下，采用雷诺时均方法获取壁面偶极子声源，并利用 FEM／AML 方法求解出叶轮和壳体偶极子源作用的流动噪声，基于声振耦合法计算出流体激励结构振动产生的外场流激噪声，分析不同性质噪声源的频谱特性，同时评估外场声源在各个频段下的贡献量。借助模态试验对透平壳体结构的模态参数进行了识别。结果表明，计算与试验振型近似，固有频率平均相对误差小于4．60％。结构的影响使得外场五阶叶频处声压最高，二阶叶频处次之。壳体偶极子作用的流激噪声对外场噪声的贡献最大，其次是壳体偶极子作用的流动噪声，叶轮偶极子作用的流激噪声对外场噪声贡献最小。研究结果为低噪声叶轮机械设计提供了一定的参考。