Mechanism Research On The Hydrocarbon Rotating Detonation Under Pintle Injection Condition

Continuous rotating detonation(CRD)shares a lot of similarities with high frequency tangential instability(HFTI)in the rocket engine and it can be one of the courses of HFTI.As one of the injection methods of liquid rocket engine(LRE),pintle injector has the intrinsic combustion stability.In this dissertation,ethylene-air CRD has been realized in a hollow chamber with designed pintle injectors.The research was conducted through numerical simulation and experimental study.Numerical simulations were conducted on the ethylene-air CRD under the condition of pintle injection.The flow fields of different pintle configurations under cold flow conditions were showed.The effects of head recirculation zone and central recirculation zone on the propellant distribution were also analyzed.After ignition,the structure of detonation wave was demonstrated clearly.The tradeoff interaction between CRD waves and injection process was analyzed.The influence of pintle configuration on the realization of the CRD was explored.It was proved that the decrease in pintle diameter could result in the decoupling of inducing shock wave and combustion flame.A series of ethylene-air CRD experiments were carried out with pintle injector.The propagation characteristics of single-wave mode,tow-wave mode and unstable mode were analyzed.And two mode transition phenomena obtained in the experiment were introduced.The frequency comparison between the combustion flame and high frequency pressure was conducted and the result proved the coupling of inducing shock wave and flame,quantitatively.The influence of the pintle diameter and insertion length on the operation range was discussed.As the pintle diameter decreased,the realization of CRD got harder.A large pintle insertion length always produced a new detonation wave and finally resulted in the mode transition from single-wave mode to tow-wave mode.The pressure changes along the combustion chamber were analyzed,and the pressure characteristics under different propagation modes were compared.It has been discovered that for fuels of hydrogen,ethylene and methane,the pressures along combustion chamber are almost the same.But for CRD of different fuel,their peak pressure,lean limit equivalence ratio and propagation frequency are different.The comparison between the frequency of CRD waves and the intrinsic acoustic frequency of the combustion chamber was conducted.The consistence between the frequency of CRD waves and HFTI was discovered.The inhibition mechanism of the pintle injector on HFTI was analyzed.