Enhanced mixing with streamwise vorticity

Waitz, Ian A.; Qiu, Y.J.; Manning, Ted; Fung, A.K.S.; Elliot, James; Kerwin, John; Krasnodebski, J. K.; O'Sullivan, Michael Noel; Tew, David; Greitzer, E. M.; Marble, Frank E.; Tan, C. S.; Tillman, T. G.

doi:10.1016/s0376-0421(96)00008-5

Cited by 107 publications

(50 citation statements)

References 8 publications

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“…Fi~.l l Streamwise vorticitv at z/2 = 3.0 discrepancy between the prediction and measurements is the flow rotation in the central recirculation zone. This is experimentally observed (Figs.9~ 11), however it is not shown in the numerical results (Figs.7,8). It is well known that the flow in the recirculation zone is highly unsteady.…”

Section: Comparison With Experimental Resulismentioning

confidence: 67%

“…In addition to streamwise vortices, counter-rotating pairs of horseshoe vortices wrapping around each inward and outward lobe peaks are also predicted. In the present study, transverse vortices are not considered since the upstream flow velocity is the same on either side of the mixer and the effect of these vortices on the flow-field is believed insignificant [4,5,8]. Fig.7 gives the vector and streamwise vorticity plots at z/2=1.5, the six ribbon vortices become wider and distorted.…”

Section: Solution Methodsmentioning

confidence: 99%

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Flow-field of an axisymmetric lobed mixer

et al. 2004

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The flow-field of a fuel/air mixing system with an axisymmetric lobed mixer was numerically investigated. Large-scale streamwise vortices are formed immediately downstream of the mixer trailing edge, stretched further downstream, and finally broken into fragments where more intense mixing occurs. Both numerical and experimental results indicate that the length required for streamwise vortices breakdown in the confined flowfield of an axisymmetric lobed mixer is much shorter than that in the case of planar lobed mixers subject to parallel freestreams. For the conditions studied, the streamwise vortices start to breakdown at three wavelengths downstream of the mixer trailing edge.

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Section: Comparison With Experimental Resulismentioning

confidence: 67%

Section: Solution Methodsmentioning

confidence: 99%

Flow-field of an axisymmetric lobed mixer

et al. 2004

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“…The TVD limiter limits the excessive fluctuations of properties around regions of high gradients and shocks 8,15 .…”

Section: Flow Solutionmentioning

confidence: 99%

Parametric study of a mixer/ejector nozzle with mixing enhancement devices

DalBello

Steffen²

2002

40th AIAA Aerospace Sciences Meeting &Amp; Exhibit

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“…More recent numerical and experimental works showed that coherent streamwise structures introduced in supersonic mixing flows increase the mixing rates between the reactants [4,5] and are able to augment the growth rate of mixing layers due to additional entrainment of fluid [6] and low sensitivity to compressibility effects. Mixing enhancement with streamwise vortices is, in fact, achieved by means of the synergistic action of turbulence, strain rates at the interface between the reactants [7], and the entrainment of the right proportions of air and injectant.…”

Section: Introductionmentioning

confidence: 99%

Supersonic Combustion of Pylon-Injected Hydrogen in High-Enthalpy Flow with Imposed Vortex Dynamics

Vergine

Crisanti

Maddalena

et al. 2015

Journal of Propulsion and Power

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The ignition and combustion characteristics of the hydrogen plume issued from two pylon-type injectors in a Mach 2.4, high-enthalpy airflow are presented. Specifically, the focus of the study is on the effects of the imposed interaction and subsequent dynamics of a system of selected supersonic streamwise vortices on the reacting plume morphology and its evolution. The design phase of the experimental campaign was carried out with a reduced-order model, with the goal of identifying peculiar interactions among streamwise vortical structures introduced in the flow of interest. Two vortex interaction modes have been selected and later implemented using ramp-type vortex generators positioned symmetrically and asymmetrically on the pylon injectors, as prescribed by the results of the simulations reported here. Hydrogen/air combustion experiments, aimed at investigating the selected cases, were conducted in the expansion tube facility of the High-Temperature Gas Dynamics Laboratory at Stanford University. Stagnation enthalpy of 2.8 MJ∕kg, static temperature of 1400 K, and static pressure of 40 kPa were the chosen test conditions. Hydrogen at 300 K was delivered with two different total injection pressures. The supersonic combustion, ignition, and flameholding characteristics were documented with schlieren photography, OH chemiluminescence, and instantaneous OH radicals planar laser-induced fluorescence. The evolution of the reactive vortical system was probed in cross-sectional planes at a distance of 1.8, 4.3, 7.6, and 10.7 cm from the fuel exit plane. The results are thoroughly analyzed and the marked difference in the plume morphology between the two cases is explained. The similarities between the injectant's predicted plumes and the measured distribution of OH radicals across the surveyed planes allow for an interpretation of the results based on supersonic vortex dynamics considerations.

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Enhanced mixing with streamwise vorticity

Cited by 107 publications

References 8 publications

Flow-field of an axisymmetric lobed mixer

Flow-field of an axisymmetric lobed mixer

Parametric study of a mixer/ejector nozzle with mixing enhancement devices

Supersonic Combustion of Pylon-Injected Hydrogen in High-Enthalpy Flow with Imposed Vortex Dynamics

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