Local and global flame characteristics in a liquid kerosene fueled supersonic combustor equipped with a thin strut

The investigations of local and global flame characteristics in a liquid kerosene fueled supersonic combustor based on the strut flame holder were conducted. A thin strut with the thickness of 6 mm is equipped in the center of the main flow, and there are two rows of oxygen injectors at the tailing edge of it to enhance the combustion. The room-temperature liquid kerosene is chosen as the fuel in the flush wall combustor without any cavity and other flame holders. The experimental condition is at flight Mach number of 6, and the Mach number is 2.8 at the entrance of the combustor, with stagnation state T-t = 1680 K, P-t = 1.87 MPa. The flame images in different equivalence ratios and oxygen mass flow rates are well captured and reproduced by the high-speed camera. Experimental results show that the flame mode could be divided into two modes, namely, the local flame mode and the global flame mode. With the injection of the oxygen, a local oxygen enriched zone forms in the recirculation zone, and the local flame generates in this location. The transition process from local flame to global flame is influenced by the equivalence ratio and the oxygen mass flow rate. There are three flame stabilization patterns being found accompanied with the changing of the equivalence ratios, and different stabilization patterns correspond to different flame modes. The main function of the injected oxygen is to establish the local flame and to strength it, then the enhanced local flame will act as the pilot flame to ignite the extra fuel to form the global flame. In addition, the oxygen will improve the efficiency of the global combustion to a certain degree. All in all, these results are valuable for the optimization of the fuel and oxygen injection strategy. (C) 2018 Elsevier Masson SAS. All rights reserved.