Numerical studies for performance improvement of a variable geometry dual mode combustor by optimizing deflection angle

As part of our efforts to study the effect of the deflection angle on combustor performance of a variable geometry dual mode combustor, the flow field characteristics and mechanisms of the combustor performance loss, which comprised of compression loss, combustion heat addition loss and expansion loss, were investigated in the variable geometry dual mode combustor numerically with a Mach number of 3, a divergence ratio of 1.76, a fuel equivalence ratio of 0.6, and a deflection angle ranging from 8 to 16. Numerical results indicated that the total pressure recovery coefficient and combustion efficiency increased with the deflection angle and there was a maximum to be obtained at the deflection angle of 12 due to the interaction between the dominant shock resulted by combustion heat release and the additional shock caused by the wedge system. Irreversible entropy generation loss was analyzed specifically in this paper to clarify and describe the combustor performance loss for the variable geometry dual mode combustor. Moreover, thrust-to-drag ratio was utilized to assess the effect of the deflection angle on combustor performance. By taking into account the flow field characteristics and combustor performance characteristics, the high combustor performance of a variable geometry dual mode combustor can be improved by selecting and optimizing the deflection angle. (C) 2017 Elsevier Masson SAS. All rights reserved.