A novel open source conjugate heat transfer solver for detonation engine simulations

Detonation based engines has attracted significant attention for propulsion applications due to their high performance with higher thermal efficiency compared to typical deflagration based aero engines. Detonation shock waves were studied in the light of Chapman-Jouget theory and Zeldovich-von Neumann-Döring (ZND) cycle, the ideal thermodynamical cycle for detonation engines. This study is devoted to the development of a numerical open source conjugate heat transfer (CHT) solver for the modelling of the detonation engines, in order to understand the effects of heat loss from pulse detonation engines on engine performance. Transport equations for the deflagration-to-detonation transition (DDT) phenomena were solved with the open source computational fluid dynamics (CFD) toolbox, OpenFOAM. Model developments have been performed based on an existing detonation solver, ddtFoam. This solver has been improved with the capacity of performing coupled deflagration-to-detonation transition and conjugate heat transfer simulations. Simulations were performed by a second-order approximate Riemann solver for Unsteady Reynolds Averaged Navier-Stokes (URANS) equations coupled with Weller combustion model and Arrhenius equations of O’Conaire reaction scheme for hydrogen-air mixture. The validation and verification of the updated version of ddtFoam, chtDdtFoam, with the existing benchmark experimental and numerical results for a homogeneous deflagration-to-detonation transition case is presented. Subsequently, pulse detonation engines were analyzed by adiabatic and constant heat flux boundary conditions. For the simulations with the constant heat flux boundary condition, a convective heat transfer coefficient has been imposed related to the natural convection around the engine and a second-type, Neumann boundary condition has been applied by making use of the Newton’s law of cooling. Consequently, the developed model has been validated with a quantitative comparison with the benchmark results.