Guide channel to improve a cavity-based scramjet combustor

A novel scramjet combustor with a guide channel (GSC) was configured by arranging an airflow channel adjacent to the cavity of a single-cavity scramjet combustor (SSC). Seven GSCs were fabricated by configuring different inlets and outlets in the guide channel. A validated numerical simulation method was used to investigate the combustor performance and related mechanisms of C 2 H 4 -fueled combustion in SSC and GSCs with an inlet Mach number of 2. A significant finding is that the airflow exiting the cavity exerts an entrainment effect on the airflow within the guide channels at the outlets, thereby providing the initial driving force for the airflow in the guide channel. The flow rate through the guide channels is dependent on both the inlet and outlet configurations. The protruding recirculation vortices at the guide channel inlets can be used to expand the low-velocity regions ahead of the fuel jets, and the incoming airflow can be leveraged to induce a partial recirculation of the airflow before the fuel jets, thereby increasing the penetration height of the C 2 H 4 jets ( ). A higher content is beneficial for increasing the residual O 2 within the cavity, which helps sustain larger combustion zones in the cavity region. Additionally, the guide channel airflow contributes to the establishment of a new combustion zone downstream of the cavity by supplying O 2 . The simulations revealed that an appropriately designed guide channel configuration in GSC-6 results in potential improvements such as better flame stability, an enhanced combustion efficiency of approximately 23%, a reduced total pressure loss of approximately 1.1%, and a lowed temperature of least 500 K for the bottom wall of the combustor downstream of the cavity. • A novel cavity-based scramjet combustor scheme was presented. • Different inlets and outlets of the guide channel were investigated. • Effects of the guide channels on scramjet combustor were analyzed. • Mechanism for achieving high combustion efficiency was revealed. • Wall temperature downstream of the cavity was effectively reduced.