Semi-empirical wake structure model of rotors using joint axial momentum theory and DES-SA method

Abstract

CFD simulation with DES-SA turbulence model are conducted to investigate the wake velocity characteristics. The turbine wake velocity distribution of axial, tangential and radial component is analysed by comparing numerical results with previous the experimental and theoretical results. The axial velocity component is continuously recovered along the axial direction. Based on the position of minimum axial velocity, turbine wake can be divided into two zones: zone of flow establishment and zone of established flow. In the zone of flow establishment, two-dipped velocity valleys of the axial velocity distribution appear along the radial direction. These two valleys are combined to one valley at the rotation axis in the zone of established flow. The tangential velocity component is the second largest and the radial velocity component accounts for only a small proportion. Both of tangential and radial velocity decreases along the axial direction. Two velocity peaks of both tangential and radial velocity appear along the radial direction. Several empirical equations of turbine wake are proposed to describe the velocity distribution.