Experimental study on combustion mode transition effects in a strut-based scramjet combustor

A strut-based scramjet combustor was operated in three different combustion modes under Mach 2.5 inflow conditions, scramjet mode, weak ramjet mode, and strong ramjet mode. The combustion mode transition effects are investigated through ground experiments. The scramjet mode occurred below the overall fuel equivalence ratio of around 0.44. Transition from the scramjet mode to the weak ramjet mode occurred at ER ∼ 0.44, accompanied by a sudden increase in thrust. By contrast, transition from the weak ramjet mode to strong ramjet mode occurred at ER ∼ 0.6125, accompanied by a sudden decrease in thrust. In particularly, combustion mode transitions significantly change the dominant characteristics of the flow field.