Numerical Simulation Of Mechanism Of Applying Coanda Effect In Gas Turbine

Circulation Control Turbine Cascade is the redesign of the traditional turbine stator cascade with the purpose of reducing the weight as well as maintaining the aerodynamic performance. The redesign includes cutting off the trailing edge and introducing into the passage the Coanda wall jet, which would be used to maintain the performance by the so called Coanda effect. This paper mainly deals with the numerical simulation of the Circualtion Control Turbine Cascades which are designed on the basis of two different baseline turbine blades respectively. The main points of the research are the performance of the cascade and the flow condition in the passage when the Circulation Cotrol Cascade works in 4 different exit Mach number.The first part of the research is involved with the subsonic cascade with an exit Mach number of 0.3. What were mainly discussed in this part includes the impact of the slot height, jet total pressure and the Coanda surface on the cascade performance and the wall jet flow condition. Compared with the baseline cascade, Circulation Control Cascade could obtain the similar performance, such as the exit flow angle, the expansion ration and the energy loss, when the invlovled geometric and aerodynamical parameters were properly selected. Changes in the jet total pressure and the curvature of the Coanda surface would lead to different aerodynamic performance. The flow condation of Coanda wall jet depends on the jet velocity and the curvature of the Coanda surface.As for the transonic Circulation Control Cascade, this paper studied the performance and the flow condition of the cascade at 3 different exit Mach numbers, such as 0.6, 0.85 and 1.1. The main research objects of this part involve the cut position, the jet total pressure and the Coanda surface. The Circulation Control Cascade could obtain the similar aerodynamic performance as the baseline cascade at Mach number 0.6, while a lower exit flow angle and expansion ratio at Mach number 0.85. As for the Mach number 1.1, although the performace of the Circulation Control Cascade is close to the baseline, the shock wave generating near the Conada surface leads to a higher energy loss.