Numerical Simulation of Flow and Heat Transfer in a Square Rotating U-Duct Using Hydrocarbon Fuel

Air turbine power generation system is considered as a feasible power generation system for hypersonic aircraft with Mach 6. However, the incoming air with high temperature cannot be used as coolant while turbine has to be cooled. Since hydrocarbon fuel is the only cooling source onboard, the scheme of fuel cooling air turbine is put forward. In this paper, square cooling channel, including inlet part, outlet part and U-duct, is established based on the typical air turbine. The hydraulic diameter of the channel is 2 mm and four types of U-ducts are used to compare the performance with simulation using k-Epsilon turbulence model. The density and specific heat capacity of fuel are considered as constant as the temperature difference in this study is small. The Reynolds number varies from 2760 to 16,559 and rotating number ranges from 0 to 6.9. The results show that the pressure distribution in radial direction is proportional to the square of radial distance and the square of rotating speed. The regulations of velocity and normalized Nusselt number distributions depend on rotating number. Furthermore, the heat transfer is enhanced with fin while the pressure loss is also increased. The position of fins cannot significantly influence pressure loss but can influence heat transfer obviously. The normalized Nusselt number of inlet-fin U-duct is higher than the outlet-fin U-duct both on leading side surface and trailing side (TS) surface, while the pressure losses for the two types of ducts are almost same.