Study of design methods and heat transfer characteristics of combined cooling structure for turbine blades with turbine inter-vane burner

The turbine inter-vane burner can greatly increase the engine thrust but brings about a harsh thermal environment to the turbine blades. Fuel-air combined cooling structure is an effective way to solve the thermal protection problem of the blades. There is a lack of research on the thermal protection of turbine blades with turbine inter-vane burner, especially systematic research on the fuel–air combined cooling structure. In this paper, the design methods of the fuel–air combined cooling structure of turbine blades with turbine inter-vane burner are proposed, and one-dimensional empirical formulas are used to design specific parameters. The heat transfer characteristics of the designed combined cooling structure are numerically investigated and analyzed without turbine inter-vane combustion, where the mainstream temperature varies from 818 K to 1414 K, the cold air temperature ranges from 500 K to 700 K, and the mass flow rate of cold air changes from 0.005 kg/s to 0.02 kg/s. The results show that in the combined cooling structure with embedded fuel channels, the heat absorbed by fuel is mostly influenced by cold air temperature compared to mainstream temperature and mass flow rate of cold air. The proportion of fuel heat absorption to overall heat absorption decreases from 0.25 to 0.13 when mainstream temperature increases from 818 K to 1418 K, as the increase of mainstream temperature has a minimal effect on the heat flux of the fuel channels, but can significantly increase the overall heat absorption. The proportion of fuel heat absorption to the overall heat absorption changes from 0.15 to 0.31 when cold air temperature increases from 500 K to 700 K, as the increase of cold air temperature enhances the heat exchange between the fuel channels and the cold air but decreases the heat exchange between the mainstream and the cold air. Besides, the flow and heat transfer performance of the combined cooling structure of turbine blades with turbine inter-vane combustion is numerically studied. The results show that the temperature of blade and fuel channels are maintained within the safe range with turbine inter-vane combustion, providing research support for subsequent studies on the fuel–air combined cooling structure of turbine blades with turbine inter-vane burner.