Study On The Flowrate Distribution And Thermal Charcteristics Of Supercritical Hydrocarbon Fuel In Thermal Coupled Parallel Channels

In the thermally coupled parallel cooling channel of the scramjet engine,the existence of the flow mal-distribution and the thermal deviation,lead to a great waste of the finite heat sink and even local over-temperature of the engine structure,which dramatically affects the engine performance and reliability.Therefore,this paper makes experimental and numerical studies on the flow distribution characteristics and heat sink utilization of the thermally coupled parallel cooling channels.The numerical model of the flow and heat transfer in the thermally coupled parallel channels will be established,and verified by validating different models.The SST k- model is used.Together with the heat transfer characteristics of single-sided heatflux,the causes of thermal deviation under the rib effect will be analyzed.The coupling relationship between thermal deviation and flow deviation will be revealed.By analyzing the mechanism of the flow distribution of the parallel regenerative parallel channels,it is found necessary to reduce or even eliminate the "positive feedback effect" by simultaneously improving the initial flow distribution and thermal load distribution.Considering the degree of freedom when designing the regenerative cooling channels and the main influencing factors of the flow distribution,the influence of the channel aspect ratio,the rib thickness and the flow area on flow distribution and the heat sink utilization will be analyzed.The optimal parameters of the channel are found based on the analysis,which greatly improves the flow distribution deteriorate problem,and optimizes the fuel heat sink utilization.In this paper,the heat transfer characteristics of the special-shaped small channel in regenerative cooling system are studied.The Newton shear effect of the wall and the influence of the rib effect on the flow heat transfer in the channel are analyzed.The single channel thermal characteristics and the flow distribution characteristics on the parallel channel of the different circulation shapes are studied.The overall cooling performance of the parallel system with different cross-section channels will be analyzed,which is expected to provide reference for the design of the cooling system.Finally,the regulation of the flow distribution of the hydrocarbon fuel in the cooling plate with parallel channels will be studied experimentally.A two-stage regenerative cooling plate test bench was built,including phase transition stage and cracking stage.The effect of single-stage throttling on the regulation of cross-critical temperature flow in the parallel system of five-channel will be studied.In addition,the suppression effects of single-stage throttle in ultra-high temperature zone under subcritical pressure will also be evaluated.Besides,the endurance tests of the cooling plate(both phase transition stage and cracking stage)under the extreme operating conditions(The maximum fuel temperature exceeds 750℃ while the maximum wall temperature exceeds 1000℃)were carried out,which provides valuable test data for the basic parameter design and throttle structure design of the engine cooling system.