Propagation Characteristics Of The Continuous Rotating Detonation Wave Fueled By Ethylene

Continuous rotating detonation is an unqiue combustion mode in supersonic airflow.With high thermodynamic efficiency,fast heat release rate and simple structure,continuous rotating detonation engine(CRDE)has huge potential benefits.There is a huge gap between lucubtated hydrogen and kerosene,which is ideal fuel of airbreathing CRDE.And hydrogen flame luminosity is too low for optical observation.Ethylene is first choice of the transition from hydrogen to kerosene,because its chemical activity is comparatively active in hydrocarbon fuel.What’s more,ethylene combustion flame is luminous enough for optical observation.In addition,the optically-accessible racetrack combustor can avoid the image distortion and correction caused by curve glass.In this thesis,the hydrocarbon continuous rotating detonation experiment facility with optically-accessible combustor was desgined and constructed.Using a combination of theoretical analysis and experimental investigation,ethylene continuous rotating detonation operating domain,propagation mechanism,flowfield structure and instability characteristics have been studied.A series of continuous rotating detonation operating domain experiment was conducted,including the influence of combustor width,oxidizer activity,fuel activity and different schemes of fuel injection.And during the analysis,the influence of oxidizer activity,fuel activity and different schemes of fuel injection were intergrated into influence of combustor width.The determination of combustor width and detonation cell size has been validated.Using the quantitative evaluation,relative strandard deviation of continuous rotating detonation wave(CRDW)propagation velocity,the effect of the CRDW propagation instability has been analysed.The CRDW propagation characteristics,flowfield structure and flame distribution are studied in one-wave homo-rotating mode and one-couple hetero-rotating mode with the combination of wall pressure measurement,high frequency pressure measurement(PCB)and high-speed photography.In the one-wave homo-rotating mode,the flame front structure presented as anti-C structure.And in one-couple hetero-rotating mode,the flame front structure presented as flat structure followed by arrow structure.Specially for the mode transition,including one-wave homo-rotating mode to one-couple hetero-rotating mode and one-couple hetero-rotating mode to one-wave homorotating mode,the high frequency pressure and corresponding flame variation process have been analysed carefully and reasonable explanations have been proposed.Finally,the CRDW instability characteristics have been studied.From the highspeed photography,pre-combust phenomenon was discovered and classified,which is considered as an important mechanism of CRDW self-sustaning and instability.And two sorts of flow-field structures are constructed based on the PCB measurement and high-speed photography.Futhermore,the shock-induced combustion at combustor aftend was validated by CH* chemiluminescence.As for CRDW instability process,the initiation process was classified and analysed by the characteristics of shock and flame.And another mechanism low frequency oscillation was found,which was determinated by degree of coupling on shock and combustion wave.