Influence of fuel inhomogeneity on detonation wave propagation in a rotating detonation combustor

Rotating detonation combustor (RDC) is a form of pressure gain combustion, which is thermodynamically more efficient than the traditional constant-pressure combustors. In most RDCs, the fuel-air mixture is not perfectly premixed and results in inhomogeneous mixing within the domain. Due to discrete fuel injection locations, local pockets of rich and lean mixtures are formed in the refill region. The objective of the present work is to gain an understanding of the effects of reactant mixture inhomogeneity on detonation wave structure, wave velocity, and pressure profile. To study the effect of mixture inhomogeneity, probability density functions of fuel mass fractions are generated with varying standard deviations. These distributions of fuel mass fractions are incorporated in 2D reacting simulations as a spatially/temporally varying inlet boundary condition. Using this methodology, the effect of mixture inhomogeneity is independently investigated to determine the effects on detonation wave propagation and RDC performance. As mixture inhomogeneity is increased, detonation wave speed, detonation efficiency, and potential for pressure gain all decrease, ultimately leading to the separation of the reaction zone from the shock wave.