A method was presented to predict the sound radiation caused by the casing vibration of a centrifugal fan on the basis of the boundary element analysis(BEA). Measuring points were laid according to the casing BEA acoustic model
and the measurement of the casing normal vibration was conducted. Then the noticeable blade-passing and rotary frequency components in the acceleration spectra were extracted and converted into velocity spectra to serve as the velocity boundary conditions of the sound radiation computation. The sound field and sound power were analyzed using the boundary element method to predict the noise generated by casing vibration. The results show that sound pressure caused by the casing vibration is much smaller than its aeroacoustic counterpart. The fan casing noise radiation may be the major noise contributor near the fan if mufflers are mounted on both the inlet and outlet of the fan. It appears that the present method may be used to predict noise radiation of other kinds of casings.
关键词
Keywords
references
NEISE W. Noise reduction in centrifugal fans: a literature survey [J]. Journal of Sound and Vibration, 1976, 45(3): 375-403.
OHTA Y, OUTA E, TAJIMA Y. Evaluation and prediction of blade-passing frequency noise generated by a centrifugal blower [J]. ASME Journal of Turbomachinery, 1996, 118(3): 597-605.
SUN H,LEE S. Numerical prediction of centrifugal compressor noise [J]. Journal of Sound and Vibration, 2004, 269(1): 421-430.
YOUNSI M, BAKIR F, KOUIDRI S, et al. Numerical and experimental study of unsteady flow in a centrifugal fan [J]. Proc IMechE: J Power and Energy, 2007, 221(7): 1025-1036.
LIU Q, QI D, TANG H. Computation of aerodynamic noise of centrifugal fan using large eddy simulation approach, acoustic analogy, and vortex sound theory [J]. Proc IMechE: J Mechanical Engineering Science, 2007, 221(7): 1321-1332.
BALLESTEROS-TAJADURA R, VELARDE-SUAREZ S,HURTADO-CRUZ J P. Noise prediction of a centrifugal fan: numerical results and experimental validation [J]. ASME Journal of Fluid Engineering, 2008, 130(9): 1-12.
KOOPMANN G H, NEISE W, CUNEFARE K A. Fan casing noise radiation [J]. ASME Journal of Vibration and Acoustics, 1991, 113(1): 37-41.
FAHY F. Foundations of engineering acoustics [M]. London, UK: Elsevier Academic Press, 2001.