Applied Research Of Fuzzy Control On Combustions Organization Of Rocket-based Combined Cycle (RBCC)

As an advanced propulsion system, RBCC (Rocke Based Combined Cycle) motor is now abstracting more and more attention of most of the major space countries in the world.In the thesis, the combustions ( ejector's first combustion and ramjet's secondary combustion ) organization of a typical structure of RBCC jet ?strutjet, was studied and analyzed , to get a better and dynamic method, to organize such kind of combustions. The secondary combustion, which has better controllability, and plays the most pivotal role on the overall performance of a strutjet, so the paper detailedly studied and analyzed the mechanism of fuel's atomization, the mechanism of fuel's spray burning, vital spray burning models and the combustion's controllability , combined with the author's practical investigation in the RBCC Lab , finally , the author got a most simple and feasible method to control the spraying burning of liquid kerosene--to set up an adjusting valve in the fuel pipeline. So the vital problem of the combustion organization was translated into how to control the aperture of the adjusting valve properly.The basic theories of fuzzy mathematics and fuzzy control were then described essentially. The research indicated that, if the secondary combustion chamber was looked on as a controlled object, with the adjusting valve as a input, the pressure and the temperature of a selected point on the inside wall of the combustion chamber as outputs, then such controlled system would be a strongly non-linear, time varying system with number of random disturbances, which resulted in huge difficulty to build an analyzed mathematics model for the spray burning of the liquid fuel, so that classic control methods were all invalid. Upon this, the author bethought of an intelligent control, which does not depend on an analytic model, fuzzy control to be applied on organizing such combustion.The dissertation accomplished the design of a fuzzy controller on the organization of the secondary combustion, how to build the fuzzy control rules, a principium design of the total fuzzy control system and a principium design of the experimental system used for accumulating inference rules. Then, the paper introduced the method of piling up inference rules, with computer simulation experiments combined with direct trial run. Then a tentative plan was offered that, CFD numerical simulation techniques and direct running trials were adopted to validate and improve the design of the fuzzy controller applied on the combustion organizations of RBCC.Finally, the paper summarized all research conclusions, and proposed some reformative advices on such techniques of the RBCC secondary combustion organization, including the necessity, the feasibility and the practical value of hardware and software being migrated to a single chip in the future were also referred, so that some theoretic provisions and tech supports are offered to the investigations of RBCC.