Abstract
AbstractThis paper is concerned with modelling the effects of swirling flow on turbomachinery noise. We develop an acoustic analogy to predict sound generation in a swirling and sheared base flow in an annular duct, including the presence of moving solid surfaces to account for blade rows. In so doing we have extended a number of classical earlier results, including Ffowcs Williams & Hawkings’ equation in a medium at rest with moving surfaces, and Lilley’s equation for a sheared but non-swirling jet. By rearranging the Navier–Stokes equations we find a single equation, in the form of a sixth-order differential operator acting on the fluctuating pressure field on the left-hand side and a series of volume and surface source terms on the right-hand side; the form of these source terms depends strongly on the presence of swirl and radial shear. The integral form of this equation is then derived, using the Green’s function tailored to the base flow in the (rigid) duct. As is often the case in duct acoustics, it is then convenient to move into temporal, axial and azimuthal Fourier space, where the Green’s function is computed numerically. This formulation can then be applied to a number of turbomachinery noise sources. For definiteness here we consider the noise produced downstream when a steady distortion flow is incident on the fan from upstream, and compare our results with those obtained using a simplistic but commonly used Doppler correction method. We show that in all but the simplest case the full inclusion of swirl within an acoustic analogy, as described in this paper, is required.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Reference81 articles.
1. Koch L. D. 2012 Predicting the inflow distortion tone noise of the NASA Glenn advanced noise control fan with a combined quadrupole–dipole model. In 18th AIAA/CEAS Aeroacoustics Conference and Exhibit, Colorado Springs, CO.
2. Lu H. Y. , Ramsay J. W. & Miller D. L. 1976 Noise of swirling exhaust jets. In 3rd AIAA Aero-Acoustics Conference, Palo Alto, CA.
3. Hughes C. E. , Jeracki R. J. , Woodward R. P. & Miller C. J. 2002 Fan noise source diagnostic test – rotor alone aerodynamic performance results. In 8th AIAA/CEAS Aeroacoustics Conference and Exhibit, Breckenridge, CO.
4. Topol D. A. 1999 TFaNS tone fan noise design/prediction system. Volume I: System description, CUP3D technical documentation and manual for code developers. Contractor Report CR-1999-208882. NASA.
5. The generation of sound by vorticity waves in swirling duct flows
Cited by
32 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献