Study on the Flow and Heat Transfer Characteristics of Fuel in Regenerative Cooling System of Scramjet Engine under Extreme Gravity

In order to study the effects of gravity level on the flow and heat transfer characteristics of aviation kerosene in the regenerative cooling system of scramjet engine, the finite volume method was used to study the flow and heat transfer of RP-3 aviation kerosene in horizontal tube at different gravity levels. The horizontal tube has an inner diameter of 1.8 mm, a wall thickness of 0.2 mm, a length of 300 mm. The working medium is RP-3 aviation kerosene. The tube wall is heated by a uniform heat flux of 400 kW/m2. Results show that the variation of the secondary flow pattern along the tube can be summarized into three kinds of evolution laws according to gravity levels. At 0g, the flow pattern on the cross-section develops from the confluence flow to the source flow, and finally becomes the confluence flow again. When the gravity level increases to 0.1g, there is a vortex above the pipe axis. The center of the vortex gradually moves downward. The confluence flow is observed finally. Once the gravity level rises to 0.3g, the center of the vortex is located below the pipe axis. The center of the vortex moves up and down around the pipe axis. With the increase of gravity level, the turbulent kinetic energy of the fluid above the axis of the tube increases, while the turbulent kinetic energy of the fluid below the axis decreases. The asymmetric distribution of turbulent kinetic energy is affected by the secondary flow induced by buoyancy effect. The increase of gravity level strengthens the convective heat transfer at the lower wall, while it weakens the convective heat transfer at the upper wall. It results in the heat transfer deterioration at the upper wall. The average convective heat transfer coefficient at the tube wall increases with the increase of the gravity level. © 2021, Science Press. All right reserved.