Fan-wake/outlet-guide-vane interaction broadband noise in turbofan jet engines is studied. The mechanism and some issues are first discussed using a two-dimensional gust-prediction model. An oblique gust-prediction model is then developed. Quasi-three-dimensional unsteady lift is calculated using a two-dimensional equivalence method. It is coupled with annular duct modes to obtain the sound power spectrum density. Spanwise turbulence integral length scales and their impact on power spectrum density predictions are investigated. A spanwise integration limit suitable for the complete frequency range is proposed. The model is validated using the NASA Source Diagnostic Test data. Sound power scaling with vane count B is examined. If solidity is maintained, the cascade response does not converge on the single-airfoil response, even for low vane counts. The sound power varies inversely with B at low frequency; it scales with B at very high frequency. The power spectrum density trend with the fan tip Mach number MT is also identified. It scales with MT5 if turbulence intensity in the fan wake scales "ideally" with MT. At offdesign conditions, fan wakes are not ideal; therefore, different speed trends apply. MT3.3 scaling is found to best fit the Source Diagnostic Test data and the prediction. Presented as Paper 2013-2151 at the 19th AIAA/CEAS Aeroacoustics Conference, Berlin, Germany, 27-29 May 2013
Investigation of Fan-Wake/Outlet-Guide-Vane Interaction Broadband Noise
AIAA journal ; 53 , 12
2015
Article (Journal)
English
Effects of Vane Sweep on Fan-Wake/Outlet-Guide-Vane Interaction Broadband Noise (AIAA 2016-2948)
British Library Conference Proceedings | 2016
|