Scale model performance test investigation of exhaust system mixers for an Energy Efficient Engine /E3/ propulsion system

Kuchar, A. P.; Chamberlin, R.

doi:10.2514/6.1980-229

Cited by 33 publications

(19 citation statements)

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“…It is to be noted that, since the sixties, much before the findings of Liepmann and Gharib (Liepmann, 1991;Liepmann and Gharib, 1992) on the important part played by the streamwise structures in mixing, artificial streamwise vorticity generation methods are used in aeronautics and combustion in order to improve mixing (Kuchar and Chamberlin, 1980;Paterson, 1984;Presz et al, 1986Presz et al, , 1994Presz et al, and 2002Zaman, et al, 1994;Zaman, 1996aZaman, , 1996bZaman, , 1999Zaman, and 2003Ramesh et al, 2006). The currently used passive generators of streamwise vortices are small tabs or chevrons placed at the nozzle exit.…”

Section: Introductionmentioning

confidence: 99%

Vortex dynamics and entrainment mechanisms in low Reynolds orifice jets

Năstase

Meslem

2008

J Vis

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Classical planar 2D-PIV measurements and time-resolved visualizations enriched by low-level processing are used for the reconstruction of the Kelvin-Helmholtz vortex passing in the near field of a circular and a 6-lobed orifice jet flow. In the circular jet, the entrainment is produced in the braid region, being interrupted in the presence of the Kelvin-Helmholtz ring. The latter compresses the streamwise vortices and alters their self-induction role. Conversely, the 6-lobed orifice geometry allows the cutting of the Kelvin-Helmholtz structures into discontinuous ring segments. Consequently, into these discontinuity regions streamwise large scale structures are developing. These streamwise structures are permanent thus controlling and enhancing the jet entrainment which is not altered by the Kelvin-Helmholtz structures passing.

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Section: Introductionmentioning

confidence: 99%

Vortex dynamics and entrainment mechanisms in low Reynolds orifice jets

Năstase

Meslem

2008

J Vis

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“…(1) Enhancing the thrust of the engines by 5%; (2) reducing the length of the exhausters; (3) reducing the fuel consumption by 2.5-3.0% (Kuchar and Chamberlin 1980); (4) reducing the noise by 3.8 dB (Crouch et al 1976); (5) reducing the infrared radiation of the stealth planes by 95%.…”

Section: List Of Symbolsmentioning

confidence: 99%

On the vorticity characteristics of lobe-forced mixer at different configurations

Mao

Zhou

et al. 2009

Exp Fluids

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Lobe-forced mixer is one typical example of the passive flow controllers owing to its corrugated trailing edge. Besides the spanwise Kelvin-Helmholtz vortex shedding, streamwise vortices are also generated within its mixing layer. The geometrical configuration of the lobe significantly affects these two types of vortices, which in turn affects the mixing performance of the mixer. In the present investigation, characteristics of mixers with five different configurations were examined and evaluated for two velocity ratios (r = 1, 0.4). The mixers have only one lobe in order to eliminate any possible interactions between neighboring vortices generated by the adjacent lobes. Hotwire anemometer was used to examine the Kelvin-Helmholtz vortices via the spectrum analysis while laser Doppler anemometer was employed to examine the streamwise vortices. It was found that there were two main frequencies for the Kelvin-Helmholtz vortices in the wake of the mixer; and the Strouhal numbers approached their respective maximum values at high Reynolds number. The rectangular mixer had similar mixing performance with the semicircular one; and both of them were better than the triangular mixer. The scalloping modification enhanced mixing by generating additional streamwise vortices while the scarfing modification could not improve the mixing performance. C I Mean streamwise circulation of the plane I, List of symbolse Penetration angle (half divergence angle) of the lobe-forced mixer k Wavelength of the lobe (m)

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“…More recently, experimental investigations conducted by Shumpert (1980), Kozlowski and Kraft (1980) and Kuchar and Chamberlin (1980) confirmed the increased mixing effectiveness produced by this type of mixer. These experimental investigations (on model mixers) were mainly directed towards establishing global performance parameter variations brought about by changes in the lobe geometry [e.g.…”

Section: Introductionmentioning

confidence: 83%

Isothermal velocity and turbulence measurements downstream of a model multilobed turbofan mixer

Koutmos

McGuirk

1989

Experiments in Fluids

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An isothermal experimental investigation of the three dimensional flow field downstream of a model multilobed turbofan forced mixer is presented. LDA measurements of the three mean velocities and corresponding turbulence intensities were obtained in the downstream duct where the turbine (primary) and fan (secondary) streams emerging from the lobes mix together. The flow development in the near field was quantified by measuring the crossplane velocities. These were found to consist of large radial flows, of order 15% of the mean axial velocities at the lobe inlet, with changing sign depending on location. The cross-plane flow is consistent with a large scale axial vortex pair (per lobe) which persists throughout the downstream duct and enhances mixing in this region. Turbulence generation and anisotropy of the turbulence structure were evident mainly in the shear layers formed as the fan and turbine streams emanated from the lobe trailing edge. Spatial uniformity in the mean and turbulent fields was measured as little as five heights downstream of the mixer exit, indicating the rapid mixing achievable in these systems.

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Scale model performance test investigation of exhaust system mixers for an Energy Efficient Engine /E3/ propulsion system

Cited by 33 publications

References 0 publications

Vortex dynamics and entrainment mechanisms in low Reynolds orifice jets

Vortex dynamics and entrainment mechanisms in low Reynolds orifice jets

On the vorticity characteristics of lobe-forced mixer at different configurations

Isothermal velocity and turbulence measurements downstream of a model multilobed turbofan mixer

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