The effect of counterflow on the development of compressible shear layers

Strykowski, Paul J; Krothapalli, Anjaneyulu; Jendoubi, S.

doi:10.1017/s0022112096001395

Cited by 59 publications

(29 citation statements)

References 40 publications

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“…We can, however, determine immediately a number of interesting things by inspection of Eq. (17). It shows that late in time, when l(t) is much larger than the length scales imposed by the initial conditions, the term on the right becomes small and the layer grows linearly at ð2=3Þ ffiffiffiffi ffi c 0 l p ðc 2 À c 1 Þ Á DV, determined only by the model coefficients and the available shear velocity difference.…”

Section: B Turbulence Quantities and Analysismentioning

confidence: 96%

“…Experiments using counterpropagating supersonic jets have suggested that these effects may be in some fashion different for the counterpropagating geometry compared to the co-flowing case. 17 Others have suggested that in the counterflowing case the growth rate can be enhanced by exciting bulk modes of the entire shear layer which are inaccessible to the coflowing case. 18 While this experiment is likely too integrated with other processes, from shocks, high-energydensity plasma effects, etc., to clearly distinguish subtleties of the coflowing versus counterflowing geometries, some of the considerations discovered in previous experiments may ultimately apply.…”

Section: Introductionmentioning

confidence: 99%

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The high-energy-density counterpropagating shear experiment and turbulent self-heating

et al. 2013

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The counterpropagating shear experiment has previously demonstrated the ability to create regions of shock-driven shear, balanced symmetrically in pressure, and experiencing minimal net drift. This allows for the creation of a high-Mach-number high-energy-density shear environment. New data from the counterpropagating shear campaign is presented, and both hydrocode modeling and theoretical analysis in the context of a Reynolds-averaged-Navier-Stokes model suggest turbulent dissipation of energy from the supersonic flow bounding the layer is a significant driver in its expansion. A theoretical minimum shear flow Mach number threshold is suggested for substantial thermal-turbulence coupling. V C 2013 AIP Publishing LLC. [http://dx.

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Section: B Turbulence Quantities and Analysismentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

The high-energy-density counterpropagating shear experiment and turbulent self-heating

et al. 2013

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“…The global analysis based on linear absolute instability concepts successfully predicts the occurrence of finite amplitude Global modes in counter-flow mixing layers (Strykowski & Niccum 1991, Strykowski et al 1996, wakes with or without suction (Hammond & Redekopp 1997, Leu & Ho 2000, Oertel 1990, Woodley & Peake 1997, hot or helium jets (Kyle & Sreenivasan 1993, Sreenivasan et al 1989, Yu & Monkewitz 1993, separated boundary layer flows over a double-bump topography (Marquillie & Ehrenstein 2003; see Figure 1), or even flickering candles (Maxworthy 1999), among many other examples.…”

Section: Global Linear Stability Analysis Of Weakly Nonparallel Flowsmentioning

confidence: 97%

GLOBAL INSTABILITIES IN SPATIALLY DEVELOPING FLOWS: Non-Normality and Nonlinearity

Chomaz

2005

Annu. Rev. Fluid Mech.

606

565

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Key Words absolute/convective instabilities, transient growth, fronts, Global modes, passive and active control ■ Abstract The objective of this review is to critically assess the different approaches developed in recent years to understand the dynamics of open flows such as mixing layers, jets, wakes, separation bubbles, boundary layers, and so on. These complex flows develop in extended domains in which fluid particles are continuously advected downstream. They behave either as noise amplifiers or as oscillators, both of which exhibit strong nonlinearities (Huerre & Monkewitz 1990). The local approach is inherently weakly nonparallel and it assumes that the basic flow varies on a long length scale compared to the wavelength of the instability waves. The dynamics of the flow is then considered as a superposition of linear or nonlinear instability waves that, at leading order, behave at each streamwise station as if the flow were homogeneous in the streamwise direction. In the fully global context, the basic flow and the instabilities do not have to be characterized by widely separated length scales, and the dynamics is then viewed as the result of the interactions between Global modes living in the entire physical domain with the streamwise direction as an eigendirection. This second approach is more and more resorted to as a result of increased computational capability. The earlier review of Huerre & Monkewitz (1990) emphasized how local linear theory can account for the noise amplifier behavior as well as for the onset of a Global mode. The present survey first adopts the opposite point of view by demonstrating how fully global theory accounts for the noise amplifier behavior of open flows. From such a perspective, there is strong emphasis on the very peculiar nonorthogonality of linear Global modes, which in turn allows a novel interpretation of recent numerical simulations and experimental observations. The nonorthogonality of linear Global modes also imposes severe constraints on the extension of linear global theory to the fully nonlinear régime. When the flow is weakly nonparallel, this limitation is so severe that the linear Global mode theory is of little help. It is then much more appropriate to develop a fully nonlinear formulation involving the presence of a front separating the base state region from the bifurcated state region.

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“…The presence of a recirculation zone behind ramps has been noticed in several previous studies (Koike et al 2006), but its ability to act as a wavemaker by supporting self-sustained motion has not been previously studied. Counterflow leads to a significant increase in the spatial growth rate of supersonic jets according to the experiments of Strykowski, Krothapalli & Jendoubi (1996). The increased mixing layer growth rate causes a reduction of the potential core length by a factor of two in counterflowing jets at Mach 2, thus a significant mixing enhancement (Gutmark, Schadow & Yu 1995).…”

Section: Introductionmentioning

confidence: 86%

Mach number effects on the global mixing modes induced by ramp injectors in supersonic flows

Massa

2014

J. Fluid Mech.

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Modern injectors for supersonic combustors (hypermixers) augment the fuel-air mixing rate by energizing the perturbation in the mixing layer. From an instability point of view, the increased perturbation growth is linked to the increased complexity of the equilibrium base flow when compared to the axisymmetric mixing layer. Common added features are streamwise vortex streaks, oblique recompression shocks and Prandtl-Meyer expansions. One of the main effects of such distortions of the mean flow is to transform the instability responsible for the creation of fine scales from a local amplified mode to a global self-sustained fluctuation. The focus of the present research is on the flow distortion induced by flushed ramps for free-stream Mach numbers in the range 2.5-3.5. The principal mean flow features are the recirculation region due to the recompression of the flow after the ramp, the shear layer over the recirculation region and the vortex streaks propagating from the ramp corners. A global three-dimensional stability analysis and three-dimensional direct numerical simulations of small perturbations of the mean flow are performed. The growth and energy distribution of the dominant and subdominant fluctuations supported by the three-dimensional steady laminar base flow are computed. The main results are the growth rates of the self-sustained varicose and sinuous modes and their correlation to the variation in the free-stream Mach number. The complex three-dimensional wavemaker is investigated by evaluating the three-dimensional eigenfunctions of the direct and adjoint modes, and the effects of the axial vorticity generated by the ramp corners are discussed.

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The effect of counterflow on the development of compressible shear layers

Cited by 59 publications

References 40 publications

The high-energy-density counterpropagating shear experiment and turbulent self-heating

The high-energy-density counterpropagating shear experiment and turbulent self-heating

GLOBAL INSTABILITIES IN SPATIALLY DEVELOPING FLOWS: Non-Normality and Nonlinearity

Mach number effects on the global mixing modes induced by ramp injectors in supersonic flows

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