Numerical Investigation of Effects of Incidence Angle on Aerodynamic Performance of Ultra-Highly Loaded Turbine Cascade

An increase in turbine blade loading is a useful means to improve the performance characteristics of gas turbines. This paper describes the results of numerical investigation for the internal flow within a low speed linear ultra highly loaded turbine cascade (UHLTC) at the off design condition. The present UHLTC has the design inlet flow, angle of 80 degree and the blade turning angle of 160 degree. The computations were made for the incidence angles from −30.0 to +7.5 degree relative to the design incidence. The two dimensional computations were carried out for eight incidence angles in order to reveal the effects of incidence on the profile loss of UHLTC. Subsequently, the three dimensional computations were performed for the several incidence angles to clarify the sensitivity of secondary flow and the associated loss generation mechanisms to the change of incidence angle. The influences of incidence variation on the blade loading were also examined. The computed results showed that the loss generation and the strength and the structure of secondary flows were much sensitive to the increase of incidence angle from the design incidence. On the other hand, the decrease of the incidence from the design one did not give the strong effect for the loss generation and the blade loading.