Turbulence Statistics of Thermo-Buoyancy Supercritical Fuel Flow in a Regenerative Cooling Channel

Active regenerative cooling with supercritical hydrocarbon fuel is considered as the most promising thermal protection method. The existence of buoyancy force would lead to strongly anisotropic flow and thermal transport characteristics. It is closely related to the cooling performance of the engine. To elucidate the mechanisms of turbulent transport, the large eddy simulation (LES) was performed to assess turbulence statistics within different turbulence scales. The results indicated that the buoyancy and inertial force together dominated the change of turbulent structure. Moreover, the spatial thermal buoyancy effect significantly suppressed the vertical velocity fluctuation. This is due to the laminar motion caused by the buoyancy force, thereby weakening the thermal transport. For the statistics of velocity fluctuation, it was found that the buoyancy force and inertial force greatly weaken the vertical and streamwise velocity fluctuation, respectively. For the statistics of thermal transport, the results pointed out that the near-wall heat transport characteristics need to be paid more attention. The thickness of the temperature mixing boundary layer led to the attenuation of vertical heat flux, which inhibited vertical temperature diffusion and predisposed to extreme conditions of heat transfer deterioration. The results can enhance the academic understanding of the heat transfer mechanism of supercritical fluids, and give guidance for further applications of thermal protection.