Numerical Study of Staged Transverse Injection of Sonic Jets into Supersonic Crossflows behind a Step

Abstract

Efficient combustion in the Scramjet combustors depends on the proper air-fuel mixing. Sufficient mixing between the supersonic airstream and the fuel jet is critical for designing of scramjet engines, and this is due to the very short residence timescale for the mixture in supersonic flows. The fluid residence time is only about of the order of milliseconds in a scramjet engine, and therefore injection and spreading of the fuel is an important issue. In this paper staged transverse injection of sonic circular jets into supersonic crossflows behind a step has been studied numerically. In comparison with parallel injection, Transverse injection provides better fuel penetration with sufficient mixing and heat release but imposes larger stagnation pressure loss. Three-dimensional Reynolds Averaged Navier-Stokes equations and k-ω sst turbulence model and the perfect gas equation have been solved by using Fluent software. The results of the numerical solution are compared and validated with available experimental data. Numerical results showed good agreement with the experimental values. The simulations correctly captured the location and shape of the main flow features. The flow filed consists of various shock waves such as bow shocks, separation -induced shocks, and barrel shocks. Results showed that Mach disc height of the second injector is larger than first injector that is due to the stagnation pressure loss of the first injection.

Keywords

• scramjet combustor
• transverse injection
• supersonic flow
• shock waves
• crossflow