Influence of air-assisted atomizer structure on ignition and flame propagation in a trapped-vortex cavity

This study explores the application of a partially-premixed and pre-evaporated air-assisted fuel supply device used in a trapped-vortex cavity. The lean-ignition fuel-air ratio (FAR) was measured under different device structures, total pressures, and incoming Mach numbers. The spanwise flame propagation process was captured by a high-speed camera. Results show that the fuel supply device has outstanding ignition performance, which can realize stable ignition under the total pressure of 0.05 MPa; the lean-ignition FAR never exceeds 0.0044 during the tests. With the increase of the total pressure, the ignition FAR decreases significantly; the rise in inlet Mach number will make the ignition FAR show a decrease-increase trend. Increasing the evaporation pipe's orifice diameter and number will reduce this ignition FAR, which can be attributed to the change in the internal flow field and fuel distribution caused by the rise of the orifice's total opening area. In addition, the flame propagation in the cavity is also affected by the structure of the fuel supply device: a larger opening area will increase the time required for flame spreading in the spanwise direction.