Investigation of cooling-air injection on the flow field within a linear turbine cascade

In order to make clear how air injection influence the internal flows of turbine guide vanes, flows in a lagre-scale linear cascade were surveyed with secondary air injection from the locations of the blade leading-edge, and the rear of the suction and the pressure surfaces. The experimental results show that the secondary air interacts with the vortices in the cascade, alters the pressure distribution over blade profile and increases the energy loss obviously. It has been found that the air injection from the rear of the suction surface leads to the largest effect on the loss increase while the air injection from the rear of the pressure surface exerts the least influence. All the injections pertaining to the experiment have been found to have little effect on the exit flow angle. Effects on secondary flows, vortex intensity, and some averaged parameters are also discussed in this paper.