A combined Computational Fluid Dynamics(CFD)-Kirchhoff method is presented for predicting high-speed impulsive noise generated by a hovering rotor blade. Two types of Kirchhoff integrated formula are used: one for the classical linear Kirchhoff formulation and the other for the nonlinear Kirchhoff formulation. An Euler finite-difference solver, TURNS, is solved first to obtain the flow field close to the blade, and then this flow field is used as an input to a Kirchhoff formulation to predict the acoustic far field. These formulas are used at Mach numbers of 0.90 and 0.95 to investigate the effectiveness of the linear and nonlinear Kirchhoff formulas for delocalized flow. During these calculations, the retarded time equation is also carefully examined, in particular, for the cases of the control surface located outside of the sonic cylinder, where multiple roots are obtained. Predicted results of acoustic far field pressure with the linear Kirchhoff formulation agree well with experimental data when the control surface is well outside of the nonlinear aerodynamics flow field. Calculation based on the nonlinear Kirchhoff equation using a sonic cylinder as a data surface show a good agreement with experimental data for both tip Mach numbers of 0.90 and 0.95. The agreement supports the conclusion that a nonlinear formulation is necessary if the data surface.
Rotor high-speed noise prediction with a combined CFD-Kirchhoff method
Die Prognose über die Geräuschentwicklung eines Rotorblattes bei Hochdrehzahl mit einer kombinierten Fluiddynamik-Kirchhoff-Methode
Forum, Annual Forum, American Helicopter Society, 50 ; 1 ; 103-113
1994
11 Seiten, 5 Bilder, 19 Quellen
Aufsatz (Konferenz)
Englisch
Kirchhoff Methods for Rotor Noise Prediction
British Library Conference Proceedings | 1995
|Kirchhoff methods for rotor noise prediction
British Library Conference Proceedings | 1995
|Helicopter rotor noise prediction using ONERA and DLR Euler/Kirchhoff methods
Tema Archiv | 1999
|