Noise generated by a leading edge in anisotropic turbulence

The noise generated by the interaction of a turbulent inflow with the leading edge of a flat plate or an airfoil is a dominant sound source, for example in rotor-stator configurations of fans and air condition units. Aeroacoustic research of this noise source often includes performing wind tunnel experiments, where the required incident turbulence is generated by passive grids or meshes. In certain cases, for example in close proximity to the grid, the generated turbulence may be anisotropic and inhomogeneous. In the present experimental study, constant temperature measurements were performed both in isotropic, homogeneous turbulence as well as in anisotropic, inhomogeneous turbulence. The results were used as an input for a common turbulence interaction noise prediction model and compared with acoustic measurements both on a flat plate and a NACA 0012 airfoil. When turbulence measurements are performed at several measurement positions to account for the inhomogeneity, the model delivers usable results for inhomogeneous and anisotropic turbulence as well. For measurements on airfoils of finite thickness, common thickness corrections should be used. Finally, a larger set of acoustic measurements were performed. The results of these measurements were scaled based on the dependencies on the parameters of the turbulence as used in the prediction model.