Investigation on low total temperature combustion characteristics of kerosene-fueled supersonic combustor

In this paper, the combustion characteristics of kerosene-fueled supersonic combustor under the conditions of Mach number 2.0, the total temperature at 700 K and the total pressure at 520 kPa (simulated flight Mach number at 3.5) were studied by using the flame stabilizing method of cavity and strut from three aspects such as blockage ratios, kerosene equivalence ratios, location and quantity of injection holes. The results showed that: (A) The combustor with the strut realized the independent and stable combustion of kerosene. The combustion-induced back pressure in the block test with blockage ratio of 20% and 10% destroyed the inlet flow conditions; while the blockage ratio was 7.3% and 5%, the incoming flow conditions when kerosene was burned stably were not destroyed. (B) The kerosene Equivalence Ratio (ER) was more likely to be disturbed upstream than the induced back pressure when it rose, and an excessively high-ER would reduce the combustion efficiency; when the equivalence ratio was constant, the combustion efficiency of the blockage ratio of 7.3% was higher than the blockage ratio of 5%. The combustion efficiencies were 0.86 (ER = 0.13) and 0.78 (ER = 0.19) when the blockage ratio was 5%, respectively; the combustion efficiencies were 0.89 (ER = 0.16) and 0.82 (ER = 0.19) when the blockage ratio was 7.3%, respectively; the combustion efficiencies were 0.51 (ER = 0.25), 0.81 (ER = 0.3), 0.65 (ER = 0.34) and 0.62 (ER = 0.42) when the blockage ratio was 20%, respectively. (C) The porous injection provided behind the strut was beneficial to the atomization of kerosene and improved the combustion efficiency of kerosene; the second injection after the cavity would reduce the combustion efficiency due to insufficient oxygen and combustion space. This study expanded the working range of ramjet and provided a reference fuel injection scheme for Turbine-Based Combined Cycle (TBCC) engine.