RANS Based Prediction of Airfoil Trailing Edge Far-Field Noise: Impact of Isotropic and Anisotropic Turbulence
M. Kamruzzaman, Th. Lutz, A. Herrig and E. Krämer
AIAA paper 2008-2867, 14th AIAA/CEAS Aeroacoustics Conference, Vancouver, Canada, 5 - 7 May 2008
A RANS based CFD flow solver (FLOWer1 ) is coupled with an airfoil Turbulent Boundary Layer Trailing-Edge Interaction (TBL-TE) far-field noise prediction scheme (Rnoise) for the application of the combined aerodynamic and aeroacoustic airfoil design process. The final form of the noise prediction model is expressed as an integral of the turbulence sources (e.g. Reynolds stress component, integral correlation length scale and velocity spectra in normal direction) over the boundary layer height and another integral in the wave number direction.2, 3 The main features of the present RANS based implementation are direct derivation of the required turbulence noise source properties by means of different turbulence model i.e. one/two equation (isotropic) and Explicit Algebric Stress Model (EARSM). Previous investigations2–4 shows that for the current noise prediction method, the turbulence anisotropy have decisive impact on the predicted noise emission. Thus, the anisotropy features of the flow in the derivation of the noise source parameter are considered by different approaches, and predicted turbulence parameters and noise spectra are
validated with the experimental data. Encouraging results are obtained. It is concluded that, one may consider anisotropy by a scaling law based on a set of measurement data in terms of quantities that are more easily determined or available from a isotropic RANS data without additional complexity and computational cost.