Investigation of convection effects on airfoil trailing edge noise generation

Abstract

Airfoil trailing edge noise is one of the fundamental aircraft noise generation mechanisms. Understanding the physics associated with trailing edge noise is of paramount importance for the design of low-noise aerodynamic shapes such as wings and high-lift devices, as well as wind and gas turbine blades, propellers, rotors and fans. The present work concerns the study of convection effects on airfoil noise generation and propagation using boundary integral formulations. A numerical tool that solves the Boundary Element Method, BEM, formulation will be developed in order to investigate the problems of interest. The Helmholtz equation will be solved with the capability of including mean flow convection effects. The incident acoustic field will be calculated by point quadrupole sources representing realistic sources typical of a turbulent boundary layer. These acoustic sources will be placed close to the airfoil trailing edge. This model problem should be representative of the realistic problem of scattering of turbulent boundary layer noise by an airfoil trailing edge. In the current work, the effects of convection on noise generation and propagation will be presented for a range of subsonic freestream Mach numbers. Several airfoil configurations with different cambers and thin and blunt trailing edges will be analyzed.