The interaction between combustion and flowfield in a rectangular scramjet combustor is investigated experimentally and numerically. The combustion mode is categorized into two modes; one is intensive combustion (IC) mode and the other is weak combustion (WC) mode. In IC mode, large separation region is generated by the precombustion shock wave, and fuel is rolled up and transported toward the core of the main airflow. The combustion is controlled by the rate of mixing, and both the mixing efficiency and the combustion efficiency are high. On the other hand, in WC mode, the fuel reacts gradually in the shear layer at the downstream of the step and the rate of heat release is low. The combustion is controlled by the rate of chemical reaction of the mixture generated in the shear layer, and the mixing efficiency and the combustion efficiency remain low.
