Solid Rocket Ramjet Combustion Process Simulation And Experimental Study

The solid-propullant ducted rocket, which combines the advantages of solid propullant rocket and ramjet propulsion, is a new kind of combined propulsion system. It offers considerable advantages for missile propulsion, such as high specific impulse, high speed, light weight, long range, high maneuver and simple structure. As the major direction of the propulsion system for supersonic missile, the ducted rocket has good prospects.It is a key technique for ducted rocket to make the second combustor operate at high efficiency and stability. The process of mixing and chemical reaction in the second combustor is very complicated, many factors affect the combustion efficiency. This thesis is aimed at providing the complete details of the combustion processes and flowfields in the second combustor, and seeking ways to improve the combustion efficiency in order to provide theoretical basis and direction for the design of second combustor.In this paper, simple reacting flow model in solid-propellant ducted rocket combustor based on Eddy Break-Up model is established. The model is used to simulate the three-dimensional combustion flowfields in an experimental motor. Some factors how to affect the combustion efficiency are discussed in the paper, including air intake and gas generator nozzle. With computations and analysis, the comprehension on the mixing and combustion process is increased, and some significative results are listed below: a) There are three recirculation regions and one vortex region in the combustor, and these recirculation regions affect the combustion process deeply, b) Increasing side-arm angle and moving side-air inletposition toward the fuel inlet can improve mixing and combustion characteristics, and increase the combustion efficiency, c) When the angle between two air-inlets equals to 180? the mixing of air and fuel can be improved, d) Adding air distributary valve at exit of air-intake can increase the amount of air bifurcated into the dome region, so the value of combustion efficiency is increased, e) Increasing gas generator nozzle number can improve combustion characteristics in the dome region and produce good condition for combustion progress, f) When the fuel streams are ejected into the second combustor with a angle, the combustion efficiency is increased, g) When the speed of fuel streams increased, the intension and temperature of recirculation region is improved. While the speed is very large, the fuel-air mixing behind the airstream is decreased and the span that the fuel flow in the second combustor is reduced, so the combustion efficiency is decreased, h) If the fuel streamsimpinge with the airstreams directly at the air-inlet exit, it make against increasing thecombustion efficiency, i) Increasing air-to-fuel ratio within proper range can increase the combustion efficiency.An experimental unchoked ducted rocket motor system is designed in this paper, and some experiments are finished.