Investigation for Effects of Equivalence Ratio on Flow Structure and Combustion Mode in a Hydrogen Fueled Scramjet Combustor

In order to investigate the effects of hydrogen equivalence ratio on flow structure and combustion mode in the scramjet combustor, the experiments were conducted in CARDC's 1kg/s direct-connected supersonic combustion wind tunnel. Schlieren, interferometry, flame emission and PLIF (Planar Laser-Induced Fluorescence) were used for better understanding the reacting flow field structure, flame development and stable status, the wall pressure measurement data was also used to analyze the combustion mode. The results were obtained under the inflow condition of Mach number 2.0, total temperature 950K and total pressure 0.8MPa. When the hydrogen equivalence ratio increased, the head of shock train moved upstream to the isolator entrance, the combustion flow structure status changed from stable to oscillation gradually, the combustion mode changed from supersonic combustion, dual-mode combustion to subsonic combustion. When the hydrogen equivalence ratio was not larger than 0.233, the combustion mode was supersonic combustion, the combustion flow structure was stable and the flame located in the cavity below shear layer. When the hydrogen equivalence ratio was between 0.233 and 0.279, the combustion induced back pressure began to disturb into the isolator and the combustion mode was dual-mode combustion. When the hydrogen equivalence ratio was larger than 0.279, the combustion mode was subsonic combustion, the combustion flow structure was unstable and the flame distribution was discontinuously broken status, the back pressure had disturbed near the center of the isolator. So, the hydrogen equivalence ratio had a great effect on flow structure and combustion mode. © 2019, Editorial Department of Journal of Propulsion Technology. All right reserved.