The flow field of an oblique detonation wave is examined. A Taylor wave is found to exist behind the detonation when operating in the weak, underdriven regime. This regime, which does not violate the second law of thermodynamics, has previously not been recognized by the aerospace community. Unsteady, normal detonations are also examined, since experimental evidence of the Taylor wave in this case provides the basis of the Taylor wave for steady oblique detonations. The oblique detonation wave is applied to hypersonic propulsion, the oblique detonation wave engine (ODWE).; A calculation technique is described that determines the performance of the ODWE and comparable diffusive scramjet engines. Diffusive scramjet performance is predicted for both constant-area and constant-pressure combustion. The calculations are performed with a calorically imperfect gas for both frozen and equilibrium flow through the subsequent expansive flow field. Performance parameters are calculated for H{dollar}sb2{dollar} and CH{dollar}sb4{dollar}, a range of freestream Mach numbers and fuel flow rates, and various inlet configurations. Results are for specific thrust, a thrust coefficient, and transverse engine size. The ODWE analysis shows the importance of including the Taylor wave, done here for the first time. An ODWE gives comparable performance to diffusive engines, and offers several advantages. The more compact size of the ODWE produces less drag, and less cooling is required. It offers considerably more design flexibility, since the wedge angle that generates the detonation can be varied to provide optimum performance over an entire flight envelope. Moreover, wedge angle variation allows easy restart capability for the ODWE.
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