Rotor-rotor interaction for counter-rotating fans. I - Three-dimensional flowfield measurements

The rotor wake/vortex flowfield generated in a scale model simulator of General Electric's counter-rotating unducted fan (UDF®) engine was investigated using three-dimensional hot-wire anemometry. The purpose was to obtain a set of benchmark experimental aerodynamic data defining the rotor wake and vortex structure, particularly in the tip region, and to relate this observed flow structure to its acoustic signature. The tests were conducted in a large, freejet anechoic chamber. Measurements of the three components of velocity were made at axial stations upstream and downstream of each rotor for conditions that simulate takeoff, cutback, and approach power