Computational and experimental studies of flow in multi-lobed forcedmixers

Elliott, J.; Manning, Ted; Qiu, Y.J.; Greitzer, E. M.; Tan, C. S.; Tillman, T. G.

doi:10.2514/6.1992-3568

Cited by 33 publications

(20 citation statements)

References 5 publications

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“…There have been several studies of a basic two-stream mixing layer originating from such a splitter plate. [4][5][6][7][8] One obvious effect of the lobed geometry is the increase in the interfacial area between the two streams that enhances the mixing. Depending on the geometry, the lobes can also introduce pairs of counter-rotating streamwise vortices that efficiently transport momentum and species across the mixing layer.…”

Section: Introductionmentioning

confidence: 99%

Noise, turbulence, and thrust of subsonic free jets from lobed nozzles

Zaman

Wang²

2002

40th AIAA Aerospace Sciences Meeting &Amp; Exhibit

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A study of noise benefit, vis-à-vis thrust penalty, and its correlation to turbulence intensities was conducted for free jets issuing from lobed nozzles. Four convergent nozzles with constant exit area were used in the experiments. Three of these were of rectangular lobed configuration having six, ten and fourteen lobes; the fourth was a circular nozzle. Increasing the number of lobes resulted in a progressive reduction in the turbulence intensities as well as in the overall radiated noise. The noise reduction was pronounced at the low frequency end of the spectrum. However, there was an increase in the high frequency noise that rendered the overall benefit less attractive when compared on a scaled-up A-weighted basis. A reduction in noise was accompanied by a commensurate reduction in the turbulent kinetic energy in the flow field. As expected, increasing the number of lobes involved progressive reduction in the thrust coefficient. Among the cases studied, the six-lobed nozzle had the optimum reduction in turbulence and noise with the least thrust penalty.

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Section: Introductionmentioning

confidence: 99%

Noise, turbulence, and thrust of subsonic free jets from lobed nozzles

Zaman

Wang²

2002

40th AIAA Aerospace Sciences Meeting &Amp; Exhibit

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“…Werle et al 12 and Eckerle et al 13 reported that the lobed mixer first induced radial secondary flows, which then grew up into streamwise vortices. Elliott et al 14 suggested that the streamwise vortices and the increased initial interfacial area, due to the convoluted geometry of the lobed mixers, strengthened jet mixing effectively, compared to circular nozzle. Manning 15 further stated that the effects of these two aspects on jet mixing were comparative.…”

Section: Introductionmentioning

confidence: 98%

Numerical research on the mixing mechanism of lobed mixer with inlet swirl in linear radial distribution

Lei

Zhang

Zhu

et al. 2015

Proceedings of the Institution of Mechanical Engineers, Part A:

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A detailed numerical simulation is presented to investigate the effects of inlet swirl and its radial distribution on the mixing mechanisms of a turbofan mixer with 12 lobes, by using the commercial ANSYS CFX solver and k-! SST model. The core-to-bypass temperature ratio and pressure ratio were set to 2.59 and 0.97, respectively, giving the Mach number of 0.66 and bypass ratio of 2.65 at mixing nozzle outlet. In the core inlet, the swirl angle was raised from 0 to 30 in a uniform or linear radial distribution manner. The inlet swirl and its radial gradient did enhance the development, interaction, and dissipation of the vortices downstream of lobed mixer, resulting in accelerating the lobed jet mixing. When the inlet swirl was less than 20 , the total pressure and thrust loss increments of lobed jet were acceptable and no more than 0.26% and 1.57%, respectively, compared with the baseline case. The results also showed that the three-dimensional separation bubble on center-body and the backflows along jet axis at the rail of center-body, resulting from the swirling flow between lobes' trough and center-body, were the dominant sources of total pressure and thrust losses for all cases with inlet swirl. And, reasonable radial distribution of inlet swirl could inhibit the aforementioned 3D separation and backflow, and thus limited the increment of jet mixing loss favorably.

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“…Following Manning's work, Belovich et al 22 performed flow visualizations using a smoke test and found that the ratio of the mixing enhancement due to streamwise vorticity and that due to increased interfacial contact area increased with the doublestream velocity ratio. Elliot et al 23 reported three primary contributors to the mixing process in lobed mixing flows, namely spanwise vortices due to the Kelvin-Helmholtz instability, and increased interfacial contact area due to the trailing edge shape. Once the flow has passed the trailing edge of the mixer, vortices are developing.…”

Section: Introductionmentioning

confidence: 98%

Aeroacoustic study of Internal Mixing Nozzles with Forced Lobed Mixers using a High-Mach Subsonic Lattice Boltzmann Scheme

Habibi

Mongeau

Casalino³

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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Numerical simulation of the transient compressible flow through lobed mixers inside turbofan engine nozzles was performed. A novel entropic Lattice Boltzmann (LB) scheme was used for the computational studies. The very large eddy simulation scheme (LBM-VLES) was used to capture sub-grid scale flow structures. The sound generation process was investigated using the porous Ffwocs William-Hawkings (FW-H) surface integral method. A contoured dual-stream nozzle with a standard 12-lobed mixer (12CL) was selected as a test case to validate the LBM simulation. A detailed model of the mixer and the nozzle was concurrently created to simulate both the internal flow through the mixer and the external jet plume. All operating boundary conditions were imposed based on available measured data for the same mixer geometry. The transient and mean flow characteristics of the flow field were obtained both inside the nozzle and within the jet plume. The transient behavior of the streamwise vortices at the nozzle exit was visualized and quantified. The Reynolds number based on nozzle exit diameter was 2.02×10 6 and the acoustic Mach number reached 0.94. Both near field and far field results and trends were in good agreement with experimental data. Specifically the predicted averaged velocity field was within the range of measure values. The overall radiated sound pressure was within 2-3dB of measured sound at all directional angles.Nomenclature c i = particle velocity f = particle distribution function f i eq = equilibrium distribution function D J = jet diameter M = Mach number (M=U /a) P = pressure P a = ambient pressure Re D = jet Reynolds number (Re D = U j D j / υ j ) T = temperature T a = ambient temperature t = time * Corresponding Author, Research assistant -AIAA member, Email: kaveh.habibi@mail.mcgill.ca. † Professor, Senior AIAA member ‡ Technical director, AIAA member § Senior physics validation Engineer, AIAA member Downloaded by ROKETSAN MISSLES INC. on February 8, 2015 | http://arc.aiaa.org |

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Computational and experimental studies of flow in multi-lobed forcedmixers

Cited by 33 publications

References 5 publications

Noise, turbulence, and thrust of subsonic free jets from lobed nozzles

Noise, turbulence, and thrust of subsonic free jets from lobed nozzles

Numerical research on the mixing mechanism of lobed mixer with inlet swirl in linear radial distribution

Aeroacoustic study of Internal Mixing Nozzles with Forced Lobed Mixers using a High-Mach Subsonic Lattice Boltzmann Scheme

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