Thermal and Mixing Efficiency Enhancement in Nonuniform-Compression Scramjets

Numerical simulations are presented to compare the heat addition, thermodynamic cycle, and mixing efficiency of generic uniform- and nonuniform-compression scramjets. The work builds on previous numerical studies that showed the coupling of nonuniform-inlet compression and thermal compression enhanced the performance of low-inlet compression scramjets. In line with previous work, both engines have the same inlet-fuelling method, inlet contraction ratio, and combustor geometry. The freestream corresponds to a Mach 10 flight condition with a dynamic pressure of 100 kPa. This study shows the mixing, heat addition, and thermodynamic cycle efficiency in the nonuniform-compression engine are higher than the uniform-compression engine. The mixing and heat release efficiency increase by 10 and 20% respectively. Enhancement of these performance parameters in the nonuniform-compression engine is caused by a staged-combustion process. This study offers new insight into how purposely induced nonuniform compression can be used to enhance scramjet engine performance.