Numerical analysis of the influence of the cooling-steam inlet total pressure on rotor cooling effectiveness

At various cooling-steam inlet total pressures, a numerical simulation was performed of the IP (Intermediate Pressure) No.1 stage of an ultra-supercritical steam turbine with the flow state in both the cooling path and the main flow passage being investigated. Moreover, the temperature field of the rotating blade surface and blade root surface was also studied. The research results show that corresponding to the given maximum and minimum inlet total pressures, the difference of the areas on the rotating blade suction surface being influenced by the cooling steam is about 10% of a relative blade height, while that of the maximum temperature difference on the blade root surface, only around 0.6 K. The higher the inlet total pressure of the cooling steam, the better the cooling effectiveness. The interference of the cooling steam to the main stream, however, is also stronger, leading to a drop of the flow efficiency. Consequently, the optimum cooling steam inlet total pressure should be chosen by taking a comprehensive consideration of the cooling effectiveness and flow efficiency.