Inflow measurements made with a laser velocimeter on a helicopter model in forward flight. Volume 10: Rectangular planform blades at an advance ratio of 0.30, 0.50 chord above the tip path plane

摘要

An experimental investigation was conducted in the 14- by 22-Foot Subsonic Tunnel at the NASA Langley Research Center to measure the inflow into a scale model helicopter rotor in forward flight (mu = 0.30). The measurements were made with a two-component Laser Velocimeter (LV) 0.50 chord above the plane formed by the path of the rotor tips (tip-path-plane). A conditional sampling technique was employed to determine the position of the rotor at the time that each velocity measurement was made so that the azimuthal fluctuations in velocity could be determined. Measurements were made at a total of 177 separate locations in order to clearly define the inflow character. The mean and standard deviation of the induced inflow ratios and the azimuthally dependent induced inflow ratios are included on 5.25 flexible disk in the pocket on the inside of the rear cover of this report. These data are presented without analysis.