Numerical simulation of convective heat transfer for an internally cooled gas turbine using liquid metal

Abstract

Air is considered as the feasible internal coolant to cool the vane of the gas turbines for the conventional cooling method all the time. However, the traditional cooling method gradually is difficult to meet the demand of increasing inlet temperature for the high-pressure turbine. Because of the excellent heat transfer performance of liquid metal, the scheme of liquid metal cooling gas turbine is put forward. In this study, numerical simulation is performed to investigate the heat transfer effects of an internally cooled vane with a U-shaped channel. Empirical formulas are employed to calculate the variable physical properties of the liquid metal. The nondimensional surface temperatures are representative of the first stage of the gas turbine. A comparison of heat transfer between the air and liquid metal coolant is presented. Results showed that the liquid metal shows more excellent heat transfer performance compared to air and the overall effectiveness values of GaIn20 cooling are approximately 366% higher than that of air cooling at Re = 50,000. Additionally, the enhancing rate of the heat transfer coefficients of GaIn20 cooling is much less than that of air cooling at Re > 50,000. For the same mass flow rate, the decreasing rate of the heat transfer coefficient for GaIn20 cooling is greater than that of air cooling with the increase of internal coolant inlet temperature. However, the pressure loss coefficient of air increases while the pressure loss coefficient of GaIn20 is almost constant with an increase in the inlet temperature of the internal coolant.