Large structure convection velocity measurements in compressible transverse injection flowfields

Gruber, Mark; Nejad, A. S.; Chen, T. H.; Dutton, J. C.

doi:10.1007/s003480050066

Cited by 55 publications

(19 citation statements)

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“…At large downstream distances (x/d j > 20), this convection velocity increases slightly, to approximately 0.85U ∞ , in agreement with previous work [30,31].…”

Section: Shear-layer Vorticessupporting

confidence: 92%

“…These vortices are convected downstream at a velocity approaching the free-stream velocity. Gruber et al [30] tracked the development and convection of jet shear-layer vortices for circular and elliptical jets, using both air and helium, in a Mach 2 crossflow, at J = 1.9. Similar studies have been conducted [31][32][33][34] to track shear-layer vortex convection, stretching and tilting.…”

Section: Introductionmentioning

confidence: 99%

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Transient interaction between a reaction control jet and a hypersonic crossflow

et al. 2018

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This paper presents a numerical study that focuses on the transient interaction between a reaction control jet and a hypersonic crossflow with a laminar boundary layer. The aim is to better understand the underlying physical mechanisms affecting the resulting surface pressure and control force. Implicit large-eddy simulations were performed with a round, sonic, perfect air jet issuing normal to a Mach 5 crossflow over a flat plate with a laminar boundary layer, at a jet-to-crossflow momentum ratio of 5.3 and a pressure ratio of 251. The pressure distribution induced on the flat plate is unsteady and is influenced by vortex structures that form around the jet. A horseshoe vortex structure forms upstream, and consists of six vortices: two quasi-steady vortices and two co-rotating vortex pairs that periodically coalesce. Shear-layer vortices shed periodically and cause localised high pressure regions that convect downstream with constant velocity. A longitudinal counter-rotating vortex pair is present downstream of the jet, and is formed from a series of trailing vortices which rotate about a common axis. Shear-layer vortex shedding causes periodic deformation of barrel and bow shocks. This changes the location of boundary layer separation which also affects the normal force on the plate. * warrick.miller@adelaide.edu.au.

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“…At large downstream distances (x/d j > 20), this convection velocity increases slightly, to approximately 0.85U ∞ , in agreement with previous work [30,31].…”

Section: Shear-layer Vorticessupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Transient interaction between a reaction control jet and a hypersonic crossflow

et al. 2018

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“…These studies have identified the importance of the windward shear layer on the entrainment process, along with the role of the CVP in the entrainment process in the wake. Because of the important role large-scale coherent structures play in the scalar transport processes, a large amount of work has been dedicated to understanding their dynamics and interaction with the supersonic crossflow (Gruber et al 1996(Gruber et al , 1997bBen-Yakar, Mungal & Hanson 2006). Furthermore, the effect of compressibility (measured by an increase in convective Mach number) on the evolution of large-scale structures and its implication for the observed decrease in mixing have also been investigated (Gruber et al 1997a).…”

mentioning

confidence: 98%

Ignition, flame structure and near-wall burning in transverse hydrogen jets in supersonic crossflow

Gamba

Mungal

2015

J. Fluid Mech.

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We have investigated the properties of transverse sonic hydrogen jets in hightemperature supersonic crossflow at jet-to-crossflow momentum flux ratios J between 0.3 and 5.0. The crossflow was held fixed at a Mach number of 2.4, 1400 K and 40 kPa. Schlieren and OH * chemiluminescence imaging were used to investigate the global flame structure, penetration and ignition points; OH planar laser-induced fluorescence imaging over several planes was used to investigate the instantaneous reaction zone. It is found that J indirectly controls many of the combustion processes. Two regimes for low (<1) and high (>3) J are identified. At low J, the flame is lifted and stabilizes in the wake close to the wall possibly by autoignition after some partial premixing occurs; most of the heat release occurs at the wall in regions where OH occurs over broad regions. At high J, the flame is anchored at the upstream recirculation region and remains attached to the wall within the boundary layer where OH remains distributed over broad regions; a strong reacting shear layer exists where the flame is organized in thin layers. Stabilization occurs in the upstream recirculation region that forms as a consequence of the strong interaction between the bow shock, the jet and the boundary layer. In general, this interaction -which indirectly depends on J because it controls the jet penetration -dominates the fluid dynamic processes and thus stabilization. As a result, the flow field may be characterized by a flame structure characteristic of multiple interacting combustion regimes, from (non-premixed) flamelets to (partially premixed) distributed reaction zones, thus requiring a description based on a multi-regime combustion formulation.

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“…Because of the important role that large-scale coherent structures play in the scalar transport process, a large amount of work has been dedicated to understand the dynamics of the these large-scale structures and their interaction with the supersonic crossflow. 14,34,35 Furthermore, the effect of compressibility (measured by an increase in convective Mach number) on the evolution of large-scale structures and its implications on the decrease in mixing have also been identified. 36 Reacting transverse jets in the supersonic regime have received less attention, partially due to the stringent requirements to initiate and sustain combustion in a supersonic flow.…”

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confidence: 98%

The reacting transverse jet in supersonic crossflow: physics and properties (invited)

Gamba

Miller

Mungal

2014

19th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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Combustion in the supersonic regime presents several challenges when compared to its low-speed counterpart. Here we review some of these challenges, and we describe some of the key features of one of the canonical flow fields in supersonic combustion: the reacting transverse jet in a supersonic crossflow (JISCF). From a practical standpoint, the key challenges that limit the control of this combustion regime are fast mixing, robust flame holding and stability. In turn, these aspects are controlled by the complex effects introduced by chemistry, compressibility, shocks and shock/flow interactions, turbulence and the underlying coupling among them. Some of their properties are discussed here. In particular, for a JISCF in a Mach 2.4 high enthalpy crossflow, the reaction zone structure, its dependence on near-wall events, boundary layer, and shock/boundary layer interaction are described. We demonstrate the paramount importance of the coupling between boundary layers and compressibility to provide mechanisms for flame stabilization at the wall. Mixing characteristics, overall structure, and the link to global parameters (momentum flux, velocity and density ratios) that characterize the JISCF, and possibly free shear supersonic flows in general, is also highlighted from non-reacting experiments. Nomenclature d = Jet exit diameter J = Jet-to-crossflow momentum flux ratio, ρ jet U 2 jet ρ a U 2 a M = Mach number p = Pressure p j,o = Jet stagnation pressure Re d = Injector jet exit Reynolds number, ρ jet U jet d µ jet r = Velocity ratio, U jet /U a s = Density ratio, ρ jet /ρ a T = Temperature U = Speed x = Streamwise direction y = Wall-normal direction z = Spanwise direction Greek letters: µ = Dynamic viscosity ρ = Density Subscript: a = Freestream conditions

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Large structure convection velocity measurements in compressible transverse injection flowfields

Cited by 55 publications

References 1 publication

Transient interaction between a reaction control jet and a hypersonic crossflow

Transient interaction between a reaction control jet and a hypersonic crossflow

Ignition, flame structure and near-wall burning in transverse hydrogen jets in supersonic crossflow

The reacting transverse jet in supersonic crossflow: physics and properties (invited)

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