In airframe-integrated scramjets, nonuniform compression fields combine with thick boundary layers developed over the vehicle forebody to deliver density stratified flow to the combustor. Additionally, in high-Mach-number scramjets fueled with wall-based injectors, delivering fuel to engine centerline air is challenging, typically relying on turbulent mixing through long combustors. This study exploits the interaction between the density-stratified flow and the vortices generated by a strategically positioned injector in the inlet to manipulate the flow field, redistributing oxygen in captured air to more accessible locations. A numerical study was performed, examining the Mach 12 rectangular-to-elliptical shape-transitioning engine flow path. With the inlet compressing air into a high-density cowl-side core-flow, hydrogen injection here through a “manipulator jet” imparts vorticity through the bulk of the engine mass flow. This high-penetration injector allowed hydrogen to pierce the core-flow, aided by the engine’s natural shock train. The injector-induced vortices ensured that centrally located and previously inaccessible air was redistributed to the more accessible cowl-side combustor surface. When combined with supplementary injectors, combustion efficiencies exceeding 80% were achievable 3.6 combustor-heights further upstream than with previous fueling configurations. These improved mixing and combustion rates suggest that combustor length could be reduced in future studies.
Improving Scramjet Performance Through Flow Field Manipulation
Journal of Propulsion and Power ; 34 , 3 ; 578-590
2017-10-19
13 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch