Abstract
The increase of turbine blade loading is the effective means to improve the perfomance of gas turbine. The increase of turbine blade loading by the increase of blade turning angle can enhance the torque obtained from single stage, and consequently decrease the size and the weight of gas turbine by reducing the numbers of the blades and stages. However, because the increase of turbine blade loading increases the pitchwise pressure gradient in the blade-to-blade passage and also the pressure difference between the pressure and the suction surfaces at blade tip, both of the passage and the tip leakage vortices became stronger. Therefore, in order to develop the practical turbine blade with the high turning angle, it is necessary to clarify the effect of the increase of blade turning angle on the secondary flow behaivor and the loss generation. In the present study, the measurements of the blade surface static pressure and the internal flow field were carried out by using the 5-hole Pitot tube for the ultra-highly loaded turbine cascade (UHLTC) with turning angle of 160 degree. The experimental results clarified that the increase of the size of tip clearance strengthened the tip leakage vortex and moved its starting point at the suction surface of blade tip toward upstream, and consequently increased the associated loss.
