Time evolution of the shear layer of a supersonic axisymmetric jet at matched conditions

Fourguette, Dominique; Mungal, M. G.; Dibble, Robert W.

doi:10.2514/6.1990-508

Cited by 17 publications

(14 citation statements)

References 10 publications

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“…Recent experiments in compressible flow shear layers indicate that the convection velocity U, of turbulent structures in supersonic shear layers is much closer to the high or low speed free stream velocities, U1 or U2, respectively, than 11% been found to be the case in subsonic shear layers (Pa.pamoschou 1989, Fourguette & Dibble 1990, Hall et al 1990. Such asymmetric behavior suggests, in turn, that the entraininent rate of free stream fluid into the turbulent illixiag region can potentially be expected t o be greatly asymmetric.…”

Section: Introductionmentioning

confidence: 92%

“…See, for example, discussion in Clemens et al (1990) and Clemens & h4ungal (1990), but also in Tam & Hu (1989) and Zhuang et al (1990). Nevertheless, there is also evidence that the structure that is there is not small scale, with a typical streamwise extent that is of the order of the local shear layer width , Fourguette & Dibble 1990, Hall et al 1990). The proposed model will also be implemented assuining that the flow can be treated as unbounded, ignoring, in other words, any influence on the convection velocity of the turbulent structures exerted by the presence of the guidewalls employed to confine the supersonic shear flow.…”

Section: Estimating the Shock Mach Numbermentioning

confidence: 99%

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On the convection velocity of turbulent structures in supersonic shear layers

Dimotakis

1991

22nd Fluid Dynamics, Plasma Dynamics and Lasers Conference

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An ansatz, complemented by appropriate selection rules, is proposed to estimate the convection velocity U, of turbulent vortical structures in supersonic shear layers. The proposed scheme assumes that, for supersonic convective Mach numbers, shocks will form in one of the two shear layer free streams. The strength of the shocks is estimated by assuming that the flow configuration is stationary with respect to perturbations in the mean flow quantities caused by the turbulent fluctuations. Given the shock strength, the convection velocity U, and the associated convective Mac11 numbers are calculated by matching the estimated total pressure at the stagnation points in the convected frame. The data indicate a convection velocity U, that is close to that of one of the free streams. That appears to be well accounted for by the proposed scheme, which also suggests that the flow can undergo large jumps in configuration with small changes in the flow parameters. This has important implications for supersonic mixing and hypersonic propulsion applications.

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Section: Introductionmentioning

confidence: 92%

Section: Estimating the Shock Mach Numbermentioning

confidence: 99%

On the convection velocity of turbulent structures in supersonic shear layers

Dimotakis

1991

22nd Fluid Dynamics, Plasma Dynamics and Lasers Conference

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“…Dibble et al (1989) and Fourguette et al (1990) used the condensation of ambient moisture and McGregor (1961), in addition to water vapor, also generated a fog using carbon tetrachloride. In blowdown wind tunnels, such as in the present work, use of water can be problematic if the total temperature drops below the freezing point, as ice can form on the windows.…”

Section: Alternative Condensing Speciesmentioning

confidence: 99%

“…The method, therefore, is similar to a finite rate chemically reacting system where two nonpremixed reactants meet within a mixing zone to form a reaction product Frieler 1988, Broadwell and. A method similar to the present one using Rayleigh scattering from condensed ambient moisture in a supersonic round jet has been used by Dibble et al (1989) and Fourguette et al (1990). Condensation induced by mixing was used by Hidy and Friedlander (1964) to obtain time-averaged visualizations of the mixing zones within a subsonic turbulent jet.…”

Section: Introductionmentioning

confidence: 99%

A planar Mie scattering technique for visualizing supersonic mixing flows

Clemens

Mungal

1991

Experiments in Fluids

145

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A planar Mie scattering technique is described which allows for the direct visualization of fluid mixing in supersonic flows. The mixed fluid is visualized by laser light sheet scattering from small alcohol droplets which condense as a result of the mixing of a vapor laden subsonic stream with a cold supersonic stream. Issues related to the formation, growth and size of the droplets are addressed. The technique reveals details of the turbulent structure which are masked by the spatial integration of schlieren and shadowgraph methods. Comparative visualizations using the vapor screen method to uniformly mark the high-speed fluid are also shown.

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“…Effects of compressibility upon round-jet structures have been experimentally studied [17][18][19]. At low compressibility (M c < 0.5), these works demonstrated the emergence of ring-like axisymmetric vortices in the transitional region.…”

Section: Introductionmentioning

confidence: 97%

Large eddy simulations of spatially growing subsonic and supersonic turbulent round jets

Maidi¹,

Lesieur²

2005

Journal of Turbulence

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This paper presents an application of large eddy simulations (LESs) using the filtered structure function model to spatially developing compressible round jets issuing from a perturbed upstream velocity profile close to a top hat. For centreline Mach number M = 0.9 and Reynolds number Re = 3600, the numerical solution compares satisfactorily against a forced-jet direct numerical simulation (DNS) and experimental data, both previously reported. High Reynolds number (Re = 36 000) 'free' jets at Mach 0.7 (case 1) and 1.4 (case 2) are studied. Here, an isotropic random white-noise perturbation is superposed on the upstream velocity. The Mach 0.7 jet has a convective Mach number of 0.35, and is weakly affected by compressibility. In this case, axisymmetric vortex rings are first shed from the nozzle and undergo alternate pairing further downstream. Then turbulence develops. The centreline velocity decay and some other statistical quantities are, in the self-similarity region, in very good agreement with previous incompressible experiments. At Mach 1.4, an impressive upstream reduction of the jet spreading rate is observed, due to an important delay of Kelvin-Helmholtz instability due to compressibility effects. Alternate pairing occurs immediately, and vortices are much more elongated in the flow direction. Further downstream, the jet becomes subsonic, develops into turbulence and spreads out again at a rate comparable with its subsonic counterpart. The potential-core length is increased by 27% from the subsonic to the supersonic case. This is in agreement with several laboratory experiments. Finally, the effects of Mach number increase upon various statistical quantities such as Reynolds stresses and radial lengthscale are studied. Results compare favourably against some experiments and temporal DNSs. From the point of view of Lumley's anisotropy invariant map evaluated on the whole physical domain, the Mach 0.7 jet is dominated by axisymmetric structures and the Mach 1.4 jet by streamwise perturbations.

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Time evolution of the shear layer of a supersonic axisymmetric jet at matched conditions

Cited by 17 publications

References 10 publications

On the convection velocity of turbulent structures in supersonic shear layers

On the convection velocity of turbulent structures in supersonic shear layers

A planar Mie scattering technique for visualizing supersonic mixing flows

Large eddy simulations of spatially growing subsonic and supersonic turbulent round jets

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