Investigations On The Structure, Rotating Mode And Lasting Mechanism Of Continuous Rotating Detonation Wave

The thermodynamic efficiency of continuous rotating detonation engine （CRDE） islarger than that of conventional constant-pressure combustion engines. CRDE couldoperate continuously just with one initiation. Due to the high rotating frequency, CRDEcould produce a roughly stable thrust, so it has huge potential benefits. Using acombination of theoretical analysis, experimental observation and numerical simulation,the flow-field structure, rotating mode and lasting mechanism of H₂/air continuousrotating detonation wave have been studied.Based on the present CRDE research results, two continuous rotating detonationcombustors are desgined and constructed with different propellant injection methods,such as injector-injector and slot-injector collision methods. A hotshot tube is desginedand constructed too, which has two convergent sections. The H₂/O2hotshot jet formingprocess is studied, and the influences of ignition opportunity, H₂/O2mixing quality andignition method have been discussed. Through lots of tests, a reliable program is gained,and the intensity of the hotshot jet has been measured quantitatively. Four CRDEinitiation methods have been discussed, and H₂/O2hotshot jet tangential injectionmethod has the best reliability. Using this method, CRDE can be initiated successfullyat a wide range of hotshot jet intensity.Lots of tests have been carried out, and there are two detonation wave rotatingmodes, which are one-direction mode and two-wave collision mode.For the one-direction rotating mode, all the detonation waves propagate along thesame direction at the same time. But the propagation direction may change during thetest process under some experiment conditions. The number of detonation waves aremainly influenced by the total mass flow rate of the propallents. The values of heightand propagation velocity of detonation wave in one-wave mode are larger than that oftwo-wave mode. For experimental results, the detonation wave propagates unstably, andits propagation velocities and peak pressure values are different from one period toanother. Within several periods, the flow-field parameters are time averaged, and theaverage parameter values along the azimuthal direction are nearly the same.For the two-wave collision mode, there are two detonation waves propagatingalong opposite directions in the combustor, colliding with each other periodically. Torealize this rotating mode, there should be an annular zone of fresh H₂/air mixtureslocated at the top of the combustor. The oscillating characteristics of the PCB results areanalyzed, and it is mainly influenced by the azimuthal angle between the pressuremeasurement point and the detonation wave collision point. Two-wave collision canlead to high pressure values, and the average flow-field parameters along the azimuthaldirection are different from each other. So this rotating mode should be avoided in thedetonation engines. Through changing test conditions, lots of tests have been carried out, and thedetonation wave lasting condition boundaries are gained. During the test, the propellantinjection process has been influenced by the rotating detonation wave. Considering thisprocess, the actual equivalence ratio of the H₂/air mixture is calculated, and thedetonation wave propagation velocity deficits are studied. For CRDE tests, when thedetonation wave propagation velocity deficit is larger than17%, the detonation wavecould not propagate continuously. Influences of the lateral expansion on the detonationwave structure and propagation process are detailed, and the calculation method ofpropagation veloctiy deficit caused by lateral expansion is deduced. For one-wave mode,the velocity deficit calculated by this method is4.6%-12%, and the corresponding valueis6%-15%for two-wave mode. Under the critical test condition, the velocity deficitcalculated by lateral expansion is close to17%, which shows that the velocity deficit ofthe continuous rotating detonation wave is mainly caused by the lateral expansioneffect.Investigations on the CRDE application are also carried out. Based ontwo-dimensional numerical simulation, the thrust vectoring ability of CRDE isdemonstrated. The influences of combustor geometric factors on the engineperformance have been analyzed by means of three-dimensional numerical simulation.The specific impulse performance can be improved by using a nozzle.