The flow field in a preswirled cooling air supply to a turbine rotor has been investigated by means of CFD-simulations. Coefficients for system efficiency are derived. The influences of various geometrical parameters for different configurations have been correlated with the help of appropriate coefficients. For some of the most important geometrical parameters of the coverplate receiver design recommendations have been found. For the preswirl nozzles the potential of efficiency improvement by contour design is highlighted.

Experiments were performed in a transonic cascade wind tunnel to investigate the film effectiveness and heat transfer coefficient on the suction side of a high-turning turbine rotor blade. The coolant scheme consisted of six rows of staggered, discrete cooling holes on and near the leading edge of the blade in a showerhead configuration. Air was cooled in order to match the density ratios found under engine conditions. Six high-frequency heat flux gauges were installed downstream of the cooling holes on the suction side of the blade. Experiments were performed with and without film and the coolant to freestream total pressure ratio was varied from 1.02 to 1.19. In order to simulate real engine flow conditions, the exit Mach number was set to 1.2 and the exit Reynolds number was set to 5×106. The freestream turbulence was approximately 1%. The heat transfer coefficient was found to increase with the addition of film cooling an average of 14% overall and to a maximum of 26% at the first gauge location. The average film cooling effectiveness over the gauge locations was 25%. Both the heat transfer coefficient and the film cooling effectiveness were found to have only a weak dependence upon the coolant to freestream total pressure ratio at the gauge locations used in this study.

This paper presents the results of an effort to improve the cooling performance of symmetrically self-ventilated induction machines in the 2-15 MW Range. Aerodynamic modifications are applied to the rotor inlet, the rotor bars, the stator bars and the stator cooling gap supports. The modificatiorts are tested in a rotating test r i g under labomtory conditions and in a prototype engine. The cooling mass flow and cooling eficiency are increased by more than 10%.

This paper reports on an investigation of the heat transfer on the suction side of a transonic film cooled turbine rotor blade in a linear cascade. Heat transfer coefficient and film effectiveness are first determined for steady conditions. The unsteady effects of a passing shock on the heat transfer are then investigated. The film cooling pattern used is a showerhead design with three rows on the suction side, one row at the stagnation point and two rows on the pressure side. The experiments were performed at engine representative temperature and pressure ratios using air as coolant. Heat transfer measurements are obtained using a Heat Flux Microsensor, and surface temperature is monitored with a surface thermocouple. Static pressure is monitored with a Kulite pressure transducer. The shock emerging from the trailing edge of the NGV and impinging on the rotor blades is modeled by passing a shock wave along the leading edges of the cascade blades. The steady-state heat transfer coefficient is 8% higher with film cooling than without film cooling. Shock heating of the freestream flow is determined to be the major contribution to the unsteady variation of heat flux, leading to an increase of about 30°C to 35°C in recovery temperature and adiabatic wall temperature.