Experimental study on the effect of equivalence ratio and injector position on flow structure and flame development in the scramjet combustor

Abstract

In order to understand the combustion characteristic clearly in the scramjet combustor, the effect of equivalence ratio and injector position on flow structure and flame development in a hydrogen fueled scramjet combustor was investigated experimentally in the present paper, various measurements included schlieren, shadow, differential interferometry, flame emission and OH*-PLIF were made during the experiments in an attempt to better understand the combustion flow field. The results were obtained under the inflow condition of Ma2.0, total temperature and total pressure were 950 K and 0.82 MPa, respectively. The combustion induced backpressure had not spread into the isolator when the equivalence ratio was 0.1, the flow structure was stable and the flame was located in the cavity shear layer in a line shape. But the backpressure of the cases when the equivalence ratio was 0.3 had spread into the isolator, the flow structure was unstable and the flame existed both in the cavity and in the core flow in a shredded paper shape. The hydrogen injected from the upstream injector burnt more intensively than that injected from the downstream injector under the same equivalence ratio condition. The above mentioned non-intrusive measuring methods had their own limitations, but the synchronous measurement method could well show a more comprehensive coupling information of the flow structure and combustion characteristics.