Study On The Combustion Characteristics Of Secondary Combustion Chamber Of Solid Rocket Scramjet

Solid rocket scramjet is an ideal power device for hypersonic flight,which has the following advantages:no ignition and flame stabilization problems,relatively simple structure,fast combat response,adjustable gas flow,etc.It is widely used in the field of hypersonic weapons.The secondary combustion chamber is an important main component of solid rocket scramjet.High temperature gas is produced by the primary combustion of solid propellant in the gas generator.The gas is injected into the refuel chamber through the jet hole and mixed with the air for combustion.Its combustion characteristics directly affect the performance of the engine.Therefore,it is great significance to study the supersonic mixing combustion characteristics and influence rules of the refuel chamber of solid rocket scramjet.A reasonable numerical simulation model and calculation method were established for supersonic mixing combustion flow in the ring-type supplementary combustion chamber,and a cold flow test was designed.The reliability of the numerical simulation method adopted in this paper was verified by the cold flow test results and the classic DLR scramjet test.The annular combustion chamber model was designed with reference to the cold flow test engine,and the mixing flow field and the combustion flow field were numerically simulated and analyzed respectively.The calculation results showed that the mixing and combustion of gas mainly occurred in the backflow area at the end of the strut and in the shear layer formed by the gas jet and air flow.And,the H₂ combustion efficiency is 48.9%,the CO combustion efficiency is 61.4%,and the total combustion efficiency is 58.7%.On the basis of the above ring-type refuel chamber model,parameters such as the radius of the inner and outer walls of the refuel chamber,the expansion Angle of the expansion section,the Angle of the strut head and the width of the strut,etc.,were changed.By means of numerical simulation,the influence rules of wall structural parameters and strut structural parameters on the flow field and combustion characteristics of the ring-type refuel chamber were studied and analyzed.The calculation results show that when the entrance height of the equal straight section changes,the combustion efficiency changes most obviously.When the equal straight section entrance height is 12mm,the combustion efficiency increases to 67%.Comprehensive analysis of the calculation results,the influence of various structural schemes on the combustion characteristics of the refuel chamber can be classified into two types:the influence on the airflow velocity and the influence on the shear layer.Because the distance between the inner and outer walls of the ring-type reburning chamber studied in this paper is small,the shear layer is the main factor influencing the combustion characteristics,that is,the combustion characteristics are sensitive to the change of the shear layer.