Effects of boundary layer transition on the vane heat transfer in an integrated intermediate turbine duct

As the inlet gas temperature of the high-pressure turbine further increases, the heat transfer of the intermediate turbine duct, which connects the high-pressure and low-pressure turbines, should also be considered. This paper investigates the heat transfer characteristics of the vane in an integrated intermediate turbine duct (IITD) by experimental, numerical, and analytical methods. The vane surface laminar-turbulent transition is found to have a key effect on the heat transfer of the vane. The surface heat transfer coefficient of the turbulent boundary layer after transition is more than twice higher than that of a laminar boundary layer. It is found that the acceleration features in the IITD can influence the flow transition and are accurately captured by the $\gamma -R{e}_{\theta }$ model. A novel correlation related to the boundary layer transition of the IITD vane is proposed to predict the local Nusselt number on the vane and can reduce the time consumption for the heat transfer prediction by about $1/4$.