On Thermodynamic Cycles for Detonation Engines

Abstract

Detonation engines are considered to potentially yield better performance than existing turbo-engines in terms of improved thermodynamic efficiency, simplicity of manufacture and operation, and high thrust-to-weight or thrust-to-volume ratio, amongst other advantages. Much effort has been put into the development of pulsed detonation engines (PDEs), including thermodynamic cycle analysis. Thermodynamic analysis of PDEs usually makes use of one-dimensional models, based on the Chapman–Jouguet (CJ) and the Zeldovich–von Neumann–Doring (ZND) theories, although increasingly sophisticated techniques, some involving numerical modeling, have also been developed lately. It is now understood that the Humphrey cycle used to model an isochoric cycle underpredicts the performance of a PDE [1]–[4]. The so-called Fickett–Jacobs (FJ) cycle is based on the CJ model. While an improvement over the Humphrey cycle, its reliance on the CJ model means that it fails to account for the physics espoused by the ZND model [1, 2]. In this paper, a discussion of the Humphrey and FJ cycles is given and the proper ZND cycle is suggested. These cycles are illustrated with a hydrogen/air mixture initially at STP. The use of a generic heat release parameter to construct the ZND cycle is provided.