Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : March 16, 2023 - March 17, 2023
The increase of turbine blade loading by the increase of blade turning angle is an effective method to improve the efficiency of gas turbines. However, it also increases the secondary losses caused by the intensifications of the horseshoe vortex, the passage vortex, and the leakage vortex, and consequently leads to the significant degradation in the aerodynamic performance of turbine. Therefore, the applications of any useful techniques to suppress the increase of aerodynamic losses are absolutely required for the development of the highly loaded turbine cascade in practical use. The squealer tip, which has a cavity on the blade tip surface, is one of the techniques to reduce the leakage flow and has been verified to be effective for the conventional turbine cascade. In this study, the performance tests were performed for the ultra-highly loaded turbine cascade (UHLTC) with three kinds of squealer tip, which were different in the cavity depth, by using the small sized wind tunnel test rig for an annular cascade. The test results showed that the application of the squealer tip with minimum cavity depth contributed to the enhancement of aerodynamic performance of the UHLTC. It increased the torque but had almost no effects on the efficiency due to the increase of the loss in the high flow coefficient region. On the other hand, its application improved the efficiency in the low flow coefficient region because of the reduction of the loss as well as the increase of the torque.
