Abstract:In order to research the rules and relationship between internal pressure pulsation and flow noise under different conditions,flow field and acoustic field of an axial-flow pump were simulated by computational fluid dynamics software Fluent and acoustic software LMS Virtual Lab numerically,and then both time and frequency domain analysis were applied.Taking the unsteady fluctuating pressure exerted by the fluid on the blade as noise source,BEM was applied to compare the difference of pump casing boundary acoustic field distributions between the condition of acoustic-only and acoustic-vibration coupling.The results show that static pressure pulsation in each checkpoint on impeller blades,guide vane blades and interfaces between rotating blades and the stationary blades show obviously discrete spectrum characteristics in spectrum diagrams,and the blade passing frequency is the dominate contents of both the pressure fluctuations and flow noise data,which manifests that the fluid-structure interaction between the rotating blades and the stationary ones may be the primary disturbance source.The flow noise frequency spectra has obvious peak at the double harmonic frequency and the triple harmonic frequency.Neglecting the pump casing vibration influence,the sound level is too high,while it is closer to practice with considering that influence.Therefore,structure vibration is very important in analyzing the noise radiation level.Noise directionality distribution chart indicates that blade noise radiation has obvious dipole characteristics.
[1]Timouchev S,Tourret J.Numerical simulation of BPF pressure pulsation field in centrifugal pump[C] //Proceedings of the 19th International Pump Users Symposium,2002:85 -105.[2]Langthjem M A,Olhoff N.A numerical study of flow-induced noise in a two-dimensional centrifugal pump-Part I:Hydrodynamics[J].Journal of Fluids and Structures,2004,19(3):349-368.[3]Langthjem M A,Olhoff N.A numerical study of flow-induced noise in a two-dimensional centrifugal pump-Part II:Hydroacoustics[J].Journal of Fluids and Struc-tures,2004,19(3):369-386.[4]Majidi K.Numerical study of unsteady flow in a centrifugal pump[J].Journal of Turbomachinery,2005,127 (2):363-371.[5]熊海芳 袁寿其 袁建平 等.离心泵内部流动诱导噪声的研究[J].水泵技术,2007,(3):7-9.[6]袁寿其 杨勇 袁建平 等.离心泵内部流动诱导噪声测量系统设计[J].排灌机械,2009,27(1):10-14.[7]杨勇.[D].镇江:江苏大学流体机械T程技术研究中心,2009.[8]袁寿其 薛菲 袁建平 等.离心泵压力脉动对流动噪声影响的试验研究[J].排灌机械,2009,27(5):287-290.[9]Jiang Y Y,Yoshimura S,Imai R,et al.Quantitative evaluation of flow-induced structural vibration and noise in turbomachinery by full-scale weakly coupled simulation[J].Journal of Fluids and Structures,2007,23(4):531 -544.[10]Cai Jiancheng,Qi Datong,Lu Fuan,et al.Numerical studies on fan casing vibration and noise radiation[C] // Proceedings of the ASME Turbo Expo 2009:Power for Land,Sea and Air,2009:8-12.