Location of Repository

Upstream-radiated rotor–stator interaction noise in mean swirling flow

By A. J. Cooper and N. Peake

Abstract

A major component of the noise in modern aeroengines is rotor–stator interaction noise generated when the wake from the rotating fan impinges on a stator row downstream. An analytically based model for the prediction of upstream-radiated rotor–stator interaction noise is described, and includes the important effect of mean swirling flow on both the rotor wake evolution and the acoustic response. The analytic nature of the model allows for the inclusion of all wake harmonics and enables the response at all blade passing frequencies to be determined.\ud \ud An asymptotic analysis based on large rotor blade number is used to model the evolution of the rotor wake downstream in a cylindrical duct carrying mean swirling flow. The equations governing the axial evolution of the wake simplify to three coupled first-order differential equations in the interior, while close to the duct walls, a boundary-layer correction is required in order to satisfy the impermeability conditions at the boundaries. At the stator location, the wake is used as input into a local linear cascade model at each radius. The interaction of each wake harmonic gives rise to acoustic waves of multiple azimuthal order which contribute to the pressure field radiated back upstream. This enables the total acoustic response to be determined in terms of cylindrical duct modes in mean swirling flow.\ud \ud The effect of stator blade geometry (thickness, camber, angle of attack) and rotor–stator separation on the total upstream-radiated noise is determined. Blade geometry is shown to have a significant effect on the noise generated, and increasing the rotor–stator gap can lead to large reductions in noise levels. Asymptotic treatment of the acoustic field, based on large azimuthal order, is also considered and used to identify the dominant contributions to the total pressure field resulting from the rotor–stator interaction. The ray structure of the acoustic modes in swirl is shown to be very different in some cases from that in uniform flow

Topics: QA, TL
Publisher: Cambridge University Press
Year: 2005
OAI identifier: oai:wrap.warwick.ac.uk:742

Suggested articles

Preview

Citations

  1. (1998). A high frequency model of cascade noise. doi
  2. (2004). A t a s s i ,H .M . ,A l i ,A .A . ,A t a s s i ,O .V .&V i n o g r a d o v ,I .V doi
  3. (1962). Axial flow compressor noise studies. doi
  4. (1999). Design selection and analysis of a swept and leaned stator concept. doi
  5. (2000). Evolution of rotor wake in swirling flow. doi
  6. (1998). G o l u b e v ,V .V .&A t a s s i doi
  7. (1996). G o l u b e v ,V .V .&A t a s s i ,H .M doi
  8. G o l u b e v ,V .V .&A t a s s i ,H .M .2000a Unsteady swirling flows in annular cascades. Part 1: Evolution of incident disturbances. doi
  9. G o l u b e v ,V .V .&A t a s s i ,H .M .2000b Unsteady swirling flows in annular cascades. Part 2: Aerodynamic blade response. doi
  10. (2001). H a n s o n ,D .B doi
  11. (2003). High frequency formulation for interaction noise in annular cascades. doi
  12. (2002). High frequency sound radiation from an annular cascade in swirling flows. doi
  13. (1997). Influence of camber on sound generation by airfoils interacting with high-frequency gusts. doi
  14. (1995). Influence of incidence angle on sound generation by airfoils interacting with high-frequency gusts. doi
  15. (1997). Influence of mean loading on noise generated by the interaction of gusts with a flat-plate cascade: upstream radiation. doi
  16. (2002). On sound generation by the interaction between turbulence and a cascade of airfoils with non-uniform mean flow. doi
  17. (1971). On the transmission of sound waves through a blade row. doi
  18. (2001). Propagation of unsteady disturbances in a slowly varying duct with mean swirling flow. doi
  19. (1994). Sound radiation from a cylindrical duct. Part 1. Ray structure of the duct modes and of the external field. doi
  20. (1990). T s a i ,C .T .&K e r s c h e n ,E .J doi
  21. (1992). The interaction between a high-frequency gust and a blade row. doi
  22. (1999). The response of a swept blade row to a three-dimensional gust. doi
  23. (1978). Unsteady vortical and entropic distortions of potential flows round arbitrary obstacles. doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.