Film Cooling Characteristics on Pressure Side in Annular Turbine Cascade

摘要

Experimental investigations were conducted to study the film cooling characteristics in a low speed annular turbine cascade using Thermochromic Liquid Crystal (TLC) technique. 18 blades were installed in the second stage of the turbine with chord length of 124.3 mm and height of 99 mm. A film hole with diameter of 4 mm, angled 28° to the tangential of the pressure surface in streamwise, was set in the middle span of the blade. The Reynolds number based on the mainstream velocity of the turbine outlet and the chord length of the rotor blade varied from 1.52×105 to 2.00×105. All measurements were made with the blowing ratio varying from 0.3 to 3.0. Air and CO2 worked as coolant to achieve the density ratio of 1.03 and 1.57. The results show that the film coverage and cooling effectiveness scale up with the blowing ratio. Higher density ratio can generate larger film cooling coverage and effectiveness. The higher the Reynolds number, the larger the film coverage and cooling effectiveness.