Ignition process in a large aspect ratio supersonic combustor based on multi-strut with liquid kerosene

The annular scram combustor is a popular configuration for combined engines owing to its compatibility with both turbines and rockets and its ability to withstand high flame temperatures. However, a significant challenge associated with this design is the large width of the combustor, which can make it difficult to establish and stabilize flames at supersonic speeds. To address this issue, under the conditions of T_t = 1680 K, P_t = 1.64 MPa, and Ma = 2.7 at the inlet of the combustor, some experimental studies have been carried out in a fan-shaped large width-to-height supersonic combustor fueled with liquid kerosene based on single-strut and multi-strut. The ignition and development of the flame were captured and analyzed using a high-speed camera, and the flame establishment process was compared across different equivalence ratios. The results revealed that the ignition process with a single-strut injection method consisted of a central-flame establishment stage with a weak flame strength. The flame establishment process under the multi-strut condition involved two stages: a central-flame establishment stage of downstream propagation and a cross-flame stage of countercurrent propagation. The multi-strut injection method improved the ignition performance of the combustor by increasing the fuel diffusion range and reducing the airflow speed. The central flame was further classified into four states based on ignition characteristics at different equivalence ratios: diffusion-weak state, diffusion-strong state, contraction-weak state, and contraction-strong state. The central-flame state had a significant effect on the flame-crossing process. The ignition performance in the multi-struts combustor was high when the central-flame was in a diffusion-strong state.