Distributed Injection for Performance Improvement of a Supersonic Combustor with Multi-staged Wall-injections

Abstract

Distributed injections by varying the number of orifices in use, were applied to improve the performance of supersonic combustor with wall/wall staged injections, especially to attain higher combustion efficiency of the second-stage fuel. The combustor performance was investigated experimentally in a Mach 2.5 airflow with a total temperature of 1500 K and a total pressure of 1.0 MPa. In the case with a strut, the distributed wall/wall staged injection caused a larger pressure rise around the second-stage injector (in the diverging section) than the staged injection with all of the orifices, while pressure rise around the first-stage injector (in minimum cross-sectional area section) was marginal. A reduction in the streamwise interval between first- and second-stage injectors with distributed injections enhanced heat release. However, the wall/wall staged injections did not produce larger thrust than the strut/wall staged injections. Removing the strut reduced the pressure rise in the case with the distributed staged injections, and the second-stage injection alone produced larger thrust than the distributed staged wall injections in the case without strut. NOMENCLATURE A- cross-sectional area of duct F- thrust (dF - thrust increment) P- pr essure X- streamwise location from step Y- spanwise location from duct center Z- lateral location from duct center φ - equivalence ratio Subscripts: i- combustor inlet 0- stagnant condition 1 - first-stage (injection) 2 - second-stage (injection)