In this paper, a numerical study into the unsteadyaerodynamic performance of a ducted tail rotor based on CFDtechnique is presented. Computation was carried out for idealforward flight condition. The general governing equations ofturbulent flow around ducted tail rotor are given, and directlysolved by using finite volume discretization and Runge-Kuttatime integration. In order to predict the aerodynamic noise, ahybrid method combing computational aeroacoustic withboundary element method (BEM) has been proposed. Theunsteady flow around rotors is calculated using the CFDmethod to get the noise source information. The radiate soundpressure is calculated using the acoustic analogy FW-Hequation in the frequency domain. The scattering effect of theduct wall on the propagation of the sound wave is presentedusing the BEM. The results are validated against existingtechnique. The sound pressure directivity and scattering effectare shown to demonstrate the applicability and validity of theapproach.
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