Analytical Models for the Thrust of a Rotating Detonation Engine

Abstract

Two models are proposed for rotating detonation engine performance. The first model is motivated by models of pulse detonation engine performance which are based on the pressure-time history within the detonation tube. The present work extends those ideas to treat rotating detonation engines with a control volume analysis that considers the forces within the combustion chamber. The key scaling parameters for this model are the height of the reactant layer just ahead of the detonation wave and the computed Chapman-Jouguet pressure and velocity. The thrust can be estimated using these parameters and a simple functional form of the pressure history on the injector surface. The second model is based on the approximation of mean axial flow and uses a conventional control volume analysis that focuses on exit conditions to evaluate thrust. The axial flow speed and thrust are evaluated based on approximating the flow following the detonation as isentropic and considering a two-dimensional expansion that converts azimuthal motion into purely axial flow. Numerical and analytic evaluation of these models demonstrates that predicted thrust and specific impulse exhibit the same scaling relationships with mixture properties as pulse detonation engines.