Research On Design And Optimization Of Integrated Scramjet Flowpath

The issue of the integrated scramjet flowpath design and optimization was studied particularly by means of a new method with numerical simulation and direct-connect test, and the effects of design factors on the performance of the components and engine were discussed comprehensively.A successive optimization process based on surrogate models was developed for complex system optimization. The approximate and iterative capabilities of several kinds of surrogate models including polynomial response surface, Kriging model, and neural network were compared. During the optimization iteration of complex system, better optimization efficiency will be achieved when several surrogate models are adopted at the same time by synthesizing their advantages of space fitness.The parameters were defined to evaluate the general performance of inlet/forebody. Two circles of successive optimization of inlet/forebody were executed on the global space and reduced space respectively with the relative remarkable performance improvement. Then, the effects of configuration parameters on performance of inlet/forebody were discussed in detail according the database built during optimization, and the result shows the cowl parameters and isolater height have more important effect on the general performance of inlet/forebody.The analysis method was developed to evaluate the performance of scramjet combustor in direct-connect test. The optimal scramjet combustor configuration and fuel distribution were obtained by abundant direct-connect tests, and the database of combustor performance were built with respect to the divergence angles of combustor shape, distribution of fuel injection and equivalence ratio.The effects of divergence angles of combustor shape, distribution of fuel injection and equivalence ratio on the combustor performance were studied systemically. The variations of combustor performance were discussed for three cases of altering injection proportions for each injection, the circumferential fuel injection distribution, and adding/reducing cavities.An available and extensible combustor control loop was designed to perform the control of thrust force increment and combustor-isolator interaction by feedback of force and isolator pressure measurements, where the fuel mass flow was regulated dynamically by fuel mass flow control system based on controllable cavitaing venturi.The evaluation method was presented to analyze the performance of scramjet engine/airframe flowpath. The successive optimization of scramjet engine/airframe was executed, and the optimal configuration was obtained with remarkable performance improvement at on-design state and off-design state, further more, the effects of fuel injection distritution and main configuration parameters on the general performance of engine/airframe were discussed in detail.This work has established a foundation to further study the effects of design factors on scramjet performance, to obtain the dominating factors, and to improve the scramjet performance.