Flow-field analysis and pressure gain estimation of a rotating detonation engine with banded distribution of reactants

Abstract

The flow-field structure and pressure gain performance of a rotating detonation engine with banded distribution of reactants have been studied using two-dimensional numerical simulations. The reactants are premixed H2/Air mixture. An unsteady reacting flow solver named rhoHLLCFoam is developed based on the open source software OpenFOAM. Unsteady Reynolds Averaged Navier-Stokes (RANS) equations are solved with second order accuracy in space and time with Harten-Lax-van-Leer-Contact (HLLC) Riemann scheme. The solver resolves the combustion phenomena through finite rate chemistry reaction model with Arrhenius form of reaction rate by using Ó Conaire scheme. After checking the reliability of the solver, two sets of cases with various inlet-area ratios (ψ) and equivalence ratios (ϕ) are conducted. The result shows that with ψ<1.0, the reactants in front of detonation waves present a discretely banded distribution which causes a series of reverse compression waves in flow-field. This paper estimates the specific impulse and specific thrust of combustion chamber. It's shown that these parameters increase with the promotion of ψ. By calculating the area-averaged stagnation pressure along axial direction of combustion chamber, the pressure gain ratio (η) of the rotating detonation engine is estimated. The result suggests that η decreases dramatically with the reduction of ψ. In order to achieve pressure gain, ψ must be greater than 0.60. Moreover, the equivalence ratio should be around unity to obtain higher value of η.