Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : March 13, 2024 - March 14, 2024
Increasing the blade turning angle for axial turbine increases blade loading. 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 reduce the increase of aerodynamic losses are absolutely required for the development of the highly loaded turbine cascade in practical use. The bowed blade with curvature in spanwise is one of the techniques to reduce the secondly flow and has been verified to be effective for the conventional turbine cascade. In this study, the performance tests were carried out for the ultra-highly loaded turbine cascades (UHLTC) with the bowed shape by using the small sized wind tunnel test rig for an annular cascade. The four types bowed shape were applied to the UHLTC, which have the convex surface on the pressure surface (termed positive bowed) or the suction surface (negative bowed) and are characterized by the bow angle. The test results showed that turbine efficiency of the positive bowed blade decreased due to lower torque and higher enthalpy drop. The negative bowed blade showed a decrease in enthalpy drop in the low flow coefficient region, but the efficiency did not increase due to the decrease in torque. In addition, an increase in bow angle further reduced efficiency for both the positive and negative bowed blades.
