Experimental Evaluation of the Effects of a Blunt Leading Edge on the Performance of a Transonic Rotor

Abstract

A rotor designed for a tip relative Mach number of 1.4 and a pressure ratio of 1.8 was tested with two different leading edge configurations, to evaluate experimentally the effects of leading edge thickness on the performance of a transonic rotor. The rotor was first tested with a leading edge thickness that resulted in a normal blade gap blockage of approximately 3 percent at the rotor tip and increased to about 4 percent at the rotor hub. The rotor leading edge was then cut back to produce a leading edge thickness which resulted in a normal blade gap blockage of about 6 percent at the tip and the hub remained at about 4 percent. The increased leading edge thickness resulted in a decrease in the rotor overall peak efficiency of 3.5 points at design speed. The major portion of this loss in efficiency occurred in the outer 30 percent of the blade span. At 90 and 70 percent of design speed, the increased leading edge thickness had a relatively small effect on rotor efficiency.