Wind-Tunnel Investigation of a Quarter-Scale Two-Bladed High-Performance Rotor in a Freon Atmosphere

摘要

A joint USAAVLABS/NASA-Langley/Bell Helicopter Company experimental investigation of a quarter-scale two-bladed teetering rotor system was conducted in the NASA-Langley Transonic Dynamics Tunnel using Freon as a test medium. Rotors tested were a dynamically similar Bell 540 rotor having -10-degree twist, and a thin-tipped rotor having 0-degree twist. Aerodynamic and loads data were obtained at advance ratios from 0.30 to 0.72 in combination with advancing-tip Mach numbers varying from 0.70 to 0.96. These data were compared to full-scale data and theory. In general, the aerodynamic test data followed predicted trends and correlated well with full-scale tunnel data in the areas of low blade loading at low advance ratio and low advancing-tip Mach numbers. The blade loads data followed the expected trends, but their magnitudes could not be readily compared to existing flight test data due to the differences between the flight test conditions, model test conditions attained, and hub impedance differences. (Author)