Recently, thermal power generation has been increasing to complement the power shortage due to the stoppage of nuclear power plants in Japan. The steam turbines are used for thermal power plants and the importance is increasing as the core component of the power generation. The turbine increase the temperature and pressure for the high efficiency. However, the aerodynamics performance of turbine cascade deteriorate by the increasing secondary flow loss due to the high loading. In this research, the loss generating mechanism in three-dimensional turbine cascade is revealed by automatic measuring system of cascade performance and CFD analysis, the secondary loss reduction is investigated analytically and experimentally.

Cavitation performance of flattened-type torque converter is investigated both experimentally with a transparent model and numerically using a conventional cavitation simulation in stalled condition. In this condition, the occurrence of cavitation is the most susceptible because of the maximum torque loadings of turbine and stator. In contrast with the cavitation inception observed at the stator in the conventional type torque converter, the cavitation initiates at the turbine inlet in the flattened-type torque converter. The latter inception is found to be caused by the strong secondary flow in the pump element due to large meridional curvature with flattened shape, resulting in high inflow velocity near the shell surface. However, the torque decrease mechanism due to cavitation is found to be similar to the conventional type; the development of cavitation around the stator separation region strengthens the blockage effect resulting in the decrease in circulating flow rate.

The fluid injection upstream from a low-speed centrifugal compressor was investigated experimentally to decide the key parameter of fluid injection effects on the compressor characteristics. Some fluid injection case demonstrates the improvement of the static pressure rise and stall suppression at rotating stall condition, whereas few impact on the compressor performance at design point. Especially when the injector exit is located near the casing aligned with the airfoil, the case of tip injection, the fluid injection momentum produces a large pressure rise and suppresses the rotating stall. As a result, the tip injection with 0.82×10^-3 of fluid injection momentum ratio extends the compressor stable operating range to 12% lower mass flow rate compared with the non-jet case.