The Pennsylvania State University (PSU) will investigate the effect of mixture concentration inhomogeneity on detonation propagation. The goal is to gain fundamental understanding of the relationship between mixture inhomogeneity and detonation properties to improve the design of pressure gain combustion systems with a focus on flow configurations found in rotary detonation engines. In most rotary detonation engine designs, fuel and oxidizer are separately injected into the main combustion chamber, leading to spatial variations in fuel and oxidizer concentration (mixture inhomogeneity) prior to the onset of detonation. Rotary detonation engines are particularly prone to concentration variations due to short mixing times and variations in fuel and oxidizer flow rates due to backpressure from the continuously traveling detonation wave. The interaction between the detonation wave and these variations in concentration can lead to reductions in the detonation wave velocity, local increases in pressure fluctuations, and changes in the failure limits of successfully propagating waves.