Hystereses and catastrophes were experimentally investigated in a cavity-based scramjet combustor.The inflow Mach number was 3.0.Fuel Equivalence Ratio(ER)was continuously reg-ulated with multi-steps to explore influences of historical regulation directions on combustion states.Two divided hysteresis loops with catastrophes were observed.By 1-D flow estimations,the first loop occurred with shock-free/separated scramjet mode transitions,while the second kept in the separated scramjet mode.This breaks through the traditional knowledge that hysteresis and catastrophe were certainly related to ramjet/scramjet mode transitions.The first hysteresis and catastrophes were attributed to flame stabilization mode transitions between the cavity shear-layer stabilized and the jet-wake stabilized,with flow separation establishment/vanishment upstream the cavities.The obvious variations of flame and shock/separation structures meant large wall-pressure changes in the expansive duct,and generated obvious thrust catastrophes.Besides,transition ER and catastrophe were larger in historical ER-increasing path because combustion effi-ciency became obviously larger as flow separation established.Difference of critical transition ERs meant the first hysteresis.The second hysteresis and catastrophes in the jet-wake stabilized mode were attributed to flame/shock interaction mode transitions between the flame/shock weak interac-tion mode and intensive interaction mode.Each transition caused slightly stronger/weaker flame interacting with slightly larger/smaller flow separation,which meant small wall-pressure changes in the expansive duct,and thus thrust catastrophe was unobvious.Hysteresis occurred as the critical transition ER was slightly higher in historical ER-increasing path because of slightly lower combus-tion efficiency under slightly smaller separation.

State Key Laboratory of High Temperature Gas Dynamics,Institute of Mechanics,Chinese Academy of Sciences,Beijing 100190,China;School of Engineering Science,University of Chinese Academy of Sciences,Beijing 100049,China;Innovation Academy for Light-duty Gas Turbine,Chinese Academy of Sciences,Beijing 100190,China

[1]Xu ZHANG;Qifan ZHANG;Zhenjie WU;Lianjie YUE;Zhanbiao GAO;Weihang LUO;Hao CHEN-.Experimental study of hysteresis and catastrophe in a cavity-based scramjet combustor)[J].中国航空学报（英文版）,2022(10):118-133

Hystereses,catastrophes,ramjet,vanishment

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