TECHNIQUES FOR COMPREHENSIVE MEASUREMENT OF MODEL HELICOPTER ROTOR AERODYNAMICS

A wide selection of sophisticated experimental measurement techniques has recently been applied to examine the aerodynamics of advanced design, Mach scaled helicopter main rotor models in a wind tunnel. Comprehensive measurements on a single rotor were made using three-dimensional smoke visualization to determine tip vortex geometries, laser velocimetry and particle image velocimetry to determine flow velocities, and pressure and hot film instrumented blades to measure airloads and boundary layer states. In addition, the effects of rotor geometry and flight condition on rotor stall were studied using minituft visualization and blade strain gauges. Finally, the interaction between the main rotor wake and the horizontal tail was quantified using unsteady pressure instrumentation, a traversing pressure probe, and shadowgraphy. This paper will describe the experimental techniques used and provide sample results.