Using an Inflow Turbulence Generator for Leading Edge Noise Predictions

Abstract

Inflow turbulence noise is often the dominant noise mechanism in turbomachines. It has been shown that the sound pressure level is related to the intensity and integral length scale of the turbulence. We utilise a methodology for generating turbulence with prescribed intensity and length scales within a detached eddy simulation. This is applied to a case of homogeneous isotropic turbulence impinging on a non-symmetric aerofoil at high Reynolds number (2.1×10⁵). The sound pressure level is estimated using Curle’s compact acoustic analogy, and compared to experimental data and analytical estimates. The intensity of the inflow turbulence is higher than expected, though it exhibits approximately homogeneous and isotropic characteristics. While the general shape of the predicted noise spectrum is correct, the magnitude differs from the experimental results by up to 17 dB. Reasons for this are elaborated, and improved predictions based on a flat plate are presented.