Characteristics of Dual Transverse Injection in Scramjet Combustor, Part 1: Mixing

TLDR

The study investigates the mixing characteristics of a dual transverse injection system in a scramjet combustor using numerical methods. The authors used 3‑D Navier–Stokes simulations with a k–SST turbulence model, solving the equations via a finite‑volume upwind scheme to examine how jet‑to‑cross‑flow momentum flux ratio and injector spacing affect mixing. Dual transverse injection yields higher mixing rate and penetration than single injection, though it incurs greater stagnation‑pressure losses, and an optimal injector spacing—larger at higher jet‑to‑cross‑flow momentum flux ratios—was identified.

Abstract

The mixing characteristics of a dual transverse injection system in a scramjet combustor were studied with numerical methods. The effects of the jet-to-cross-flow momentum flux ratio and the distance between injectors on mixing characteristics were investigated. Three-dimensional Navier–Stokes equations, including the k–! SST turbulencemodel,weresolvedwiththe finitevolumemethodadoptingtheupwindmethodofEdwards’lowdiffusion flux splitting scheme. It is shown that the mixing characteristics of a dual transverse injection system are very differentfromthoseofasingleinjectionsystem.Therearinjection flowisstronglyinfluencedbyblockageeffectsdue to the momentum flux of the front injection flow and thus has higher expansion and penetration than the front injection flow. The dual injection system has a higher mixing rate and a higher penetration but have more losses of stagnation pressure than the single injection system. It is also shown that there is an optimal distance between injectors for mixing characteristics and that the optimal distance increased as the jet-to-cross-flow momentum flux ratio increased.