Secondary injection of gases into a supersonic flow

Abstract

The How field around the injection port for secondary injection of a gas nor:mal to a supersonic stream has been studied in a series of wind-tunnel experiments. The experiD1ents were conducted at freestream Mach numbers of 1.38 to 4.54. Gaseous nitrogen, argon, and helium were used as injectants. New information concerning pressure fields, concentration fields, and shock shapes was obtained. A scale pal'ameter has been calculated, based on a simple, inviscid model of the How field. This scale parameter gives a good general correlation of the data. Use of this scale parameter allows prediction of a simple scaling law for the side forces generated by secondary injection. This side-force scaling law is in approximate agreement with existing rocket motor test results.

Physical Insight into Fuel-Air Mixing for Upstream-Fuel-Injected Scramjets via Multi-Objective Design Optimization

“…Fuel/air mixing is predominantly driven by two types of largescale motions, namely, streamwise vortex pairs generated on either side of the jet in the near-field mixing process as well as vortices developing at the jet/freestream interface orienting themselves tangent to the interface [12,15]. Transverse injection at a normal angle (α j 90 deg) inherently incurs a large total pressure loss due to the relatively strong bow shock present immediately upstream of the injector.…”

“…The interactions between fuel and air including mixing, ignition, and combustion occur at an extremely short time scale, rendering the development of effective and reliable fuel injection systems crucially important. The significance of fuel injection in high-speed airbreathing engines has brought about a considerable number of preceding studies for the last half-century, starting with early experimental and analytical investigations of underexpanded injection flowfields in supersonic crossflow [12,13]. Fuel injection for supersonic combustion commonly aims to achieve both high efficiency and effectiveness simultaneously, primarily targeting three objectives [11,14]: 1) high mixing efficiency to ensure desirable mixture of fuel and air before entering the combustor, 2) minimum total pressure losses in the mixing process to maintain high stream thrust, and 3) proper penetration of the injected fuel into the airstream for ignition and sustained combustion.…”

Large-Eddy/Reynolds-Averaged Navier-Stokes Simulations of Sonic Injection into Mach 2 Crossflow

“…Figure 1 shows the flowfield features that result from transverse injection into a supersonic crossflow. Optical methods [1][2][3][4][5][6][7] allowed researchers to discern the major flow phenomena, such as the prominent bow shock, the Mach disk in the interior of the injection plume, the counter-rotating vortices in the injection plume, and the wake and vortex regions beneath the injection plume. More recent studies [8][9][10][11][12][13][14] have used laser diagnostics in addition to optical techniques and gas-sampling methods to glean more information from wind-tunnel tests.…”

Shock wave-boundary layer interactions at the supersonic flow around three-dimensional configurations

“…За допомогою аналізу даних по розподілу статичного тиску на поверхні стінки визначено п'ять зон, що харак-теризують відрив та приєднання пограничного шару, первинні та вторинні вихори перед та після струменю. Тривимірна конфігурація з круглим інжекційним отво-ром досліджена авторами робіт [12][13][14]. Відмічається складна топологія потоку із значними завихреннями навколо газового струменю та викривленням стрибка ущільнення.…”