Design Method for High Ma Number Counter Rotating Turbine Blades

The relative Ma number from rotor outlet is often quite large in high pressure turbine, especially in vaneless counter rotating turbine. Therefore, it is necessary that appropriate blades are adopted for high Ma working circumstances. In this paper, 13 design parameters are firstly chosen through analysis of the key factors that affecting the high Ma turbine performance. Then the non-uniform rational B spline method is employed to parameterize the model of turbine blade, and made the dynamic parameters of key geometric parameters associate. Furthermore, a parametric modeling method is developed for high Ma turbine cascade. Later, the method is applied to design a big bend angle and high Ma turbine blade used for a counter rotating turbine of VCE. Simulations are carried out to verify the modeling and the results prove that design demands under both working patterns can be satisfied, which implies that the blades modelling method developed in this paper is appropriate for high Ma turbine blades.