Processing And Properties Of Active Cooling Silicon Carbide Microchannels For Combustion Chamber

With the development of hypersonic vehicles,the heat management of the scramjet engine,which is the power system of hypersonic vehicle,is going to be more and more serious.Therefore,it is very important to find an effective heat management scheme.Using for reference the cooling technology of rocket thrust chamber,the active cooling scheme is considered to be one of the most effective and feasible methods.In this paper,the high efficient heat transfer characteristics of the microchannels has been applied to the heat protection of the combustor chamber.A type of diamond grinding wheel cutting method was provided to process the microchannels of silicon carbide ceramics.The basic theory of diamond grinding removal for hard brittle materials was analyzed.Both the effects of processing parameters and parameters of the grinding wheel on the shape and the surface quality of microchannels were studied.Based on the above study,the optimization processing parameters were selected as follows:n=6000r/min,vf=90mm/min,ap=0.15mm the diamond grit was size 120,the thickness of wheel is 0.5mm.And the samples required for subsequent research were prepared.The heat transfer test device were designed and manufactured and the experimental platform was built.Heat transfer performance of SiC microchannels with different hydraulic diameters including Dh=0.667mm,Dh=0.774mm and Dh=0.857mm were studied.The results show that a better heat transfer effect in single-phase convection heat transfer experiments was obtained by a larger hydraulic diameter microchannels.However,in the two phase boiling heat transfer experiment,the medium hydraulic diameter microchannels shown a better comprehensive performance.Besides,the heat transfer performance of two different coolant,deionized water and absolute ethanol were compared and analyzed.A novel combustor integrated with microchannels was designed and manufactured,and an experimental system used to evaluate the microchannel active cooling combustor was successfully established.A series of experiments were carried out to focus on the combustion performance and heat transfer characteristic of microchannels.The results show that the temperature of the combustor wall was obviously decreased and showing a pretty well temperature uniformity.Such related research results provide a reference for SiC microchannels application in active cooling system of supersonic vehicle scramjet.