Distribution of Enthalpy in Rotating Detonation Engine

Abstract

In Rotating Detonation Engine (RDE), the detonation wave rotates inside the annulus of thecombustor. After initiation by a pre-detonator, this detonation wave can be sustained by thecontinuous supply of fuel and oxidiser. The frequency of rotation is reported to be of the orderof 5-10 KHz indicating a near continuous operation which can be used in rocket andairbreathing propulsion systems. An experimental study on the RDE is being carried out atNational Centre for Combustion Research and Development (NCCRD), Indian Institute ofTechnology (IIT), Madras using hydrogen and air system. In addition,N2H4 - N2O4 hypergolicsystemreported in literature is considered for comparative study. In order to understand thevarious processes undergone by the flow through the RDE, a detailed thermodynamic analysisis performed. The procedure is explained in greater detail for the better understanding of thevarious state properties in the entire flow field. The flow field comprises of detonation wave,trailing oblique shock wave and Prandtl- Mayer expansion waves. There are two slip lines,one separating the fresh reactants and inert combustion products of the previous cycle ofdetonation wave propagation and another separating the products of detonation combustionand the shocked inert products. Though all the state properties will be evaluated, the enthalpydistribution is considered in the entire flow field of RDE and discussed. This provides theknowledge of the energy availability in various flow regimes and the extent of energyconversion due to detonative combustion, flow expansion, shock compression, and axial flowexciting through the combustor outlet. Propulsion parameters such as axial specific thrust andspecific impulse are computed to show the capability of this modelling approach.