The Computation And Analysis Of Heat Transfer Of Platelet Cooled Microchannel On The High Temperature And High Pressure Gas Wall

The channel scale on transpiration cooling for the platelet thrust chamber of liquid propellant rocket engine is approaching micron dimension. It is very possible that micro-scale effects will occur in the flow and heat transfer of the channel. In the past, researchs on flow and heat transfer in the platelet micro-channel are mostly based on macro-scale theory. The rationality of the result got from the microscale theory should be analyzed by microscale theory.In the paper, an overview of transpiration cooled platelet and micro-scale theory is presented. The velocity slip model and the temperature jump model for the research on flow and heat transfer in the platelet micro-channel are developed. While programs developing, two dimensional temperature distribution of the fluid in the channel and one dimensional temperature distribution of the platelet are obtained. Macro-scale theory is used also to compute the heat transfer in platelet micro-channel. The temperature difference model is established, and the function for the temperature distribution in the platelet micro-channel is obtained, numerical calculation is carried by using commercial solftware named FLUENT. Through comparison and analysis the result gained from micro-scale theory and macro-scale theory, we can drew several conclusions as follows:1. As the Knudsen number (Kn number)is very small, the inaccuracy would be neglect,when the macro-scale theory is used to solve the problems which were proposed in the paper.2. The temperature field got from macroscale theory and microscale theory are similar In the microscale theory, two demension heat transfer model is considered, and the temperature difference of the fluid between central axis and nearby the wall is considerably big.3. The hot-dip-depth and temperature difference between fluid and platelet wall are influenced by many factors, such as the coefficient of heat conductivity of platelet and fluid, the coolant fluid, the Knudsen number, and so on.High temperature make Kn number become bigger, and then microscale effects become notable. Howerve, high pressure make Kn number become smaller, and then microscale effects minished.4. The paper proved that when the cooling channel belongs to the transitional region from macro-scale to micro-scale, whether the macro-scale theory or the micro-scale theory will be used depends on the accuracy that the researcher reqired, and does not need to depend on the Knudsen number.