Numerical Investigation on Pylon and Flush Wall Injection in Cold Coaxial Jets

The dual combustion ramjet (DCR) engine is considered one of the promising engines for the hypersonic missile propulsion system. This paper reveals the non-reacting flow characteristics of the DCR engine with the influence of pylon and wall injections in coaxial jets using numerical investigation. The supersonic combustor of the DCR engine is modeled and analysed using the commercial CFD software ANSYS 18.0. The three-dimensional compressible Reynolds-averaged Navier-Stokes (RANS) equations coupled with the SST k - ω turbulence model have been used to analyse the coaxial mixing characteristics of the jets. The numerical study is validated with the experimental data and agrees with it for further investigation. The pylon and wall injectors are located symmetrically at the gas generator’s nozzle exit, and the air is used as the injectant to simulate gaseous fuel. The pylon and wall injection results are compared with the actual DCR engine. In a typical DCR engine, the shock waves generated from the gas generator nozzle enhance the mixing of the coaxial jets with minimum total pressure loss. The pylon injection induces more shock interactions along the flow direction within the supersonic combustor leading to higher total pressure loss than the wall injection. The pylon injection provides the spatial distribution of fuels compared to the wall injection in the coaxial supersonic flow field.