Humidity effects on the aerodynamic performance of a transonic compressor cascade

Abstract

Humid air degrades gas turbine aerodynamic performance. However, little is known about humidity effects on the compressor flow field. Blade loading distribution, deviation, and loss coefficient have been measured in a transonic compressor cascade for relative humidity (RH) values of 20, 32, 42, 45, 49 and 53% at Mach number of 1.11 and incidence of +5°. In addition, numerical studies have been conducted for the same conditions by incorporating the Classical Nucleation Theory (CNT) model and Hertz-Knudsen droplet growth model into ANSYS FLUENT. As the relative humidity increases, due to condensation, the pressure of upstream of the shock on the suction surface is increased; the pressure on the pressure surface is decreased; and shock is pushed downstream, reducing shock strength. However, due to the negligible shock-induced boundary layer separation, humidity has little effect on deviation. Loss coefficient is increased as the relative humidity increases because, even though the shock loss is reduced, heat addition to the flow from condensation decreases total pressure.