Numerical simulation of pulse detonation engine phenomena

This computational study examines transient, reactive compressible flow phenomena associated with the pulse detonation engine. The PDE is an intermittent combustion engine that relies on unsteady detonation wave propagation for combustion and compression elements of the propulsive cycle. The computations focus on high order numerical simulations of the generic PDE configuration with simplified and detailed complex reaction kinetics. Both one- and two-dimensional simulations of the high speed reactive flow phenomena are performed and compared to determine the applicability of 1D and quasi-1D simulations for performance characterization. Examination of the effects of the combustion reaction mechanism, the use of a pressure relaxation length for 1D simulations, the presence of a convergent or divergent nozzle, and the complexity of the reaction mechanism is made. Engine performance parameters such as specific impulse, in addition to engine noise estimates within and external to the detonation tube, are presented and used in evaluating characteristics of the devices. The present simulations suggest that a great deal of useful performance and noise related data may be obtained even from quasi-one-dimensional computations of the pulse detonation engine with simplified reaction kinetics. Very similar centerline pressure profiles are observed when comparing complex and simplified reaction kinetics simulations throughout the course of the PDE cycle, suggesting that the inclusion of appropriate reaction time scales in a simplified mechanism could be sufficient to be able to represent critical PDE thermodynamic processes, including noise generation.; Comparisons of PDE tube performance with differently shaped nozzle extensions yield very interesting results. Not only are quasi-1D simulations able to capture flow and reaction processes reasonably well as compared with a full 2D axisymmetric simulation, but the competition between the effects of nozzle shape on the thrust wall and on the nozzle pressure contribution to impulse could be studied systematically. Similarly comparable predictions of noise generation for the different nozzle configurations could be achieved using the quasi-1D simulations. The present computations suggest that issues of performance and noise may be studied in a straightforward manner, making the present method useful as a design tool for PDE optimization.