Investigation of the near wake of a propfan

Abstract

The flow in the wake of a model single-rotation propfan rotor operating in a wind tunnel was traversed with a hot-wire anemometer system designed to determine the three periodic velocity components. Special data acquisition and data reduction methods were required to deal with the high data frequency, narrow wakes, and large fluctuating air angles in the tip-vortex region. The model-tip helical Mach number was 1.17, simulating the cruise condition. Although the velocity field is complex, flow features such as viscous velocity defects, vortex sheets, tip vortices, and propagating acoustic pulses are clearly identified with the aid of a simple analytical wake theory.