Some Results From Tests on a High Work Axial Gas Generator Turbine

Abstract

Aerodynamic test results are presented for a single-stage, axial gas generator turbine of 3.9:1 design pressure ratio. Test results are also shown for a number of variants on this design, indicating the effect on aerodynamic performance of degree of reaction, nozzle and rotor aspect ratio, rotor blade channel design, rotor tip clearance, radial work distribution and effect of nozzle endwall contouring. Detailed aerodynamic observations are compared with analytical predictions. Of the design parameters examined, rotor blade aspect ratio, tip clearance and channel diffusion were found to have the greatest influence on losses. Operation at pressure ratios above the design was found to be improved with “open” rotor stagger, yielding a reduced design point degree of reaction.