Reduction of aerodynamic noise radiated from Wells turbine

Abstract

This study focuses on the reduction of aerodynamic noise radiated from a Wells turbine. A Wells turbine is composed of a cascade of blades arranged around the rotational axis. As a fundamental study, we measured the aerodynamic sound radiated from an airfoil with a plasma actuator mounted near the trailing edge of the two-dimensional airfoil. At a normal airfoil, discrete frequency noise is clearly observed at small attack angles. The peak level of spectra for working plasma actuators decreased compared with the normal airfoil. The plasma actuator was effective in reducing the discrete frequency noise radiated from the airfoil. This noise radiated from the airfoil depended on the electrode position, geometry of the electrode, and applied frequency. The effective geometry of the plasma actuator to reduce this noise was clarified.