The effect of blade solidity on the aerodynamic loss of a transonic turbine cascade

Abstract

Past research at Virginia Tech (VPI) explored the aerodynamic loss of the transonic VPI turbine blade, which 1s based on the pitchline profile of a high pressure turbine blade for a large commercial aircraft gas turbine. The current experiment explores the loss of the VPI blade for different axial solidity ratios near the design point. Ten percent changes in the solidity ratio were accomplished by varying the blade pitch and changing the blade stagger to maintain a constant throat to spacing ratio. Reaction, exit angle and exit Mach number were kept constant with this method. Cascades with three different solidities were tested in VPI’s transonic blowdown wind tunnel. Downstream total pressure loss and static pressure measurements were obtained. In addition, inviscid calculations were made for each case. Static pressure contours and Mach number profiles from the calculations were compared with the experimental results.

A ten percent decrease in solidity caused no cascade loss penalty as compared to the Baseline solidity for a wide range of Mach numbers. Calculated blade Mach number profiles agreed well with experimental profiles except on the suction side near the throat and downstream of the shock/boundary layer interaction. Predicted downstream static pressure values agreed well with experimental values, except that the inviscid code tended to over-predict the pressure rise across the suction side shocks.