Aeroacoustic Calculation of a Transonic Propeller Using Kirchhoff Method

Kurzfassung

In this paper, a program system, based on the existing codes at DLR, is applied for the noise prediction of a three-dimensional transonic propeller. Firstly, the aerodynamic flowfield is computed by using the FLOWer code running in the Euler mode. The best aerodynamic result is achieved by adjusting several parameters. Then the farfield acoustic pressure is calculated using Kirchhoff method. Here the Kirchhoff surface is defined as a nonrotating cylinder entirely surrounding the propeller blade. A detailed study is given to show the influence of the radious and height of the cylinder on the acoustic pressure in the farfield. The results obtained by the Farassat method are also presented and compared with Kirchhoff results and experimental data. It is demonstrated that the Kirchhoff method, which considers most of the nonlinear effects, leads to better results than the linear method compared with the experiment. It also indicates that the present program system is applicable in the case of transonic propeller.