The Relationship Between Thermal Process And Potential Performance In Dual-mode Scramjet At Ma4-7

To improve performance is a difficult project for Dual-Mode supersonic combustor ramjet(Dual-Mode scramjet)development.To know how much the performance potential will be and on what conditions it will be realized is the premise to resolve this difficulty.This dissertation is aimed to find performance potential conditions for Dual-Mode thermodynamic cycle.All possible paths for Dual-Mode thermodynamic cycle are found based on the classical quasi-one-dimensional channel flow theory with heat interaction and the latest understanding to Dual-Mode scramjet proceeding.The scope of possible optimum cycle paths is minimized by studying cycle loss.Then an equivalent thermo-process cycle model is devised with characteristic Mach number in combustor as the token of the cycle according to the manner of an assured optimum process,which represents a family of thermo-processes possible to produce optimum performance.Some sub physical models in this model are improved.The validity of the model is proved by combustion tests.Thus a method is formed to analysis the relationship between the equivalent thermo-process and performance(processperformance relationship)for Dual-Mode scramjet,in which are taken into account all necessary elements including gas components,specific heat ratio,dissociation effect,wall friction and heating loss.This method rapidly gives evaluation of the relationship between inflow conditions,area-heat distribution and the performance potential.Using this method the author examined process-performance relationships for Dual-Mode combustor at flight Mach number from 4 to 7,as well as effect of some factors on these relationships,including inflow parameters,equivalence ratio,dynamic pressure,and nozzle expansion degree.From the examination,the performance potential conditions are found,and the formulized sensitivity relationship between the performance potential and combustor incoming parameters is deduced,which can be used to match the processes between engine components.Comprehensive understanding is obtained on thermo-process design and control for Dual-Mode scramjet cycle from the investigation.Results provide insights toward a useful roadmap for future effort to develop combustion organization technology according to an optimum thermo-process.Using this method the author also examined effect of typical ground facility test gases on the process-performance relationships at flight Mach number from 4 to 7.From the sight of optimum performance(no concerning the flameout boundary),the author suggests that according to the obtained optimum thermo-process,which is demonstrated with appropriate vitiated test gas in ground facility,redesigning the combustor divergent degree to obtain the combustor configuration for pure air condition.The equivalent thermo-process cycle analysis method developed in this dissertation should be more applied,because it has been demonstrated in this dissertation that the method is prospective in understanding the thermo-process and helpful to design combustor key parameters.