Optical diagnostics in a detonation-driven direct-connected circular combustor fueled with hydrogen for mach 10 scramjet

Various optical methods are applied to study flame characteristics of a circular-cross-section combustor for a Mach 10 scramjet. Experiments are performed on a direct-connected test facility fueled by hydrogen and driven using hydrogen/oxygen detonation. The circular-cross-section combustor is advantageous in solving thermal inhomogeneity, corner boundary layer and aircraft integration problems. However, it is difficult to use traditional optical measurement methods, which require large-sized measurement windows. In this study, tunable diode laser spectroscopy and a multi-view imaging system are used with small windows. High repetition rate measurements allow the effective time of facility, which is approximately 5 ms in this case, to be obtained. The dynamic flame characteristics are diagnosed upstream and downstream of the cavity with/without strut injection. When combined with proper orthogonal decomposition to obtain the flame pulsation state during the effective time period, the method is expected to be effective for engine performance evaluation and numerical simulation verification.