The Off-Design Performance of a Low Pressure Turbine Cascade

Abstract

The ability of a given blade profile to operate over a wide range of conditions is often of the utmost importance. This paper reports the off-design performance of a low pressure turbine rotor root section in a linear cascade. Data were obtained using pneumatic probes and surface flow visualisation. The effects of incidence (+9, 0, −20 deg.), Reynolds No. (1.5, 2.9, 6.0×105), pitch-chord ratio (0.46, 0.56, 0.69) and inlet boundary layer thickness (0.011, 0.022 δ*/C) are discussed. Particular attention is paid to the three-dimensionality of the flow field. Significant differences in the detail of the flow occur over the range of operating conditions investigated. It is found that the production of new secondary loss is greatest at the lower Reynolds numbers, positive incidence and the higher pitch-chord ratios.