Numerical Simulation Of Steam-cooling Turbine Blades

As the technology of gas turbine is developing rapidly, the temperature at the inlet of the turbine is rising higher and higher. For the modern advanced gas turbine, this temperature is way above the melting point of the component material of blade, so the cooling of blade is necessary. Steam cooling, which came out as a new method in the 1970's, has two advantages over air cooling. On the one hand, with better feature in specific heat and thermal conductivity than air, steam has higher cooling efficiency, which enables the blade to stand higher temperature. On the other hand, steam cooling reduces the cooling air from compressor, which is favorable for improving the efficiency of the compressor and consequently improves the efficiency of the whole gas turbine.In this study, the flow channel model is processed with Pro/E and ICEM is used to mesh the blade and the flow model. Then the numerical simulation analysis of the flow field and temperature field is conducted with Ansys-CFX. Below are the details:1. When air is used as the cooling medium, calculate the distribution of the surface temperature of the steam cooling blade, the distribution of velocity, pressure and temperature of gas flow channel and the cooling effect under different air flow rates. Summarize the highest blade surface temperatures, the temperatures of the blade middle section and how the cooling efficiency varies under different air flow rates.2. When steam is used as the cooling medium, calculate the distribution of the surface temperature of the steam cooling blade, the distribution of velocity, pressure and temperature of gas flow channel and compare the result with that of air cooling. The cooling effects of blade are compared and summarized under different steam flow rates and under different inflow methods.3. Based upon the computation, add a cooling sleeve before the blade to jet impingement cooling the high-temperature area on the root of blade and re-divide the grid to compute. By comparing with the previous calculation, it is found that under the same steam flow rates impingement-film cooling can achieve better cooling effect than using film cooling only.