Large eddy simulation analysis of a 18-lobe convoluted mixer nozzle

Ooba, Yoshinori; Kodama, Hidekazu; Nakamura, Y.; Nozaki, Osamu; Yamamoto, Kazuomi; Nishizawa, Yasuki

doi:10.2514/6.2002-717

Cited by 8 publications

(4 citation statements)

References 5 publications

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“…Originally, a steady RANS approach in conjunction with a turbulence model (38)(39)(40)(41)(42) and a vortex-element approach (43) were used to calculate lobed mixer flows, and the effect of boundary conditions on the numerical results were also considered in these studies (39)(40)(41) . Subsequent studies with regard to mixing characteristics of lobes have simulated multiple or realistic lobed nozzles using a large-eddy simulation (LES) approach (44,45) . More recently, Brinkerhoff, et al (46) investigated the mixing mechanisms downstream of an axisymmetric lobed mixer using an unsteady RANS approach, showing the transient behaviour of the lobed-mixer flow.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical study of mixing characteristics of a rectangular lobed mixer in supersonic flow

Feng¹,

Shen²,

Wang

et al. 2015

Aeronaut.j.

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A combined experimental and computational study on a rectangular lobed mixer is performed. A series of simulations based on a steady Reynolds-averaged Navier-Stokes Simulation (RANS) are conducted to analyse the mixing mechanisms of large-scale streamwise structure shed by the trailing edge of lobed mixer, with emphasis being placed on the effect of turbulence modeling and inflow conditions. The simulations are validated in respect of velocity and scalar distribution against the data obtained through Particle Image Velocimetry (PIV) and Nanoparticle-based Planar Laser Scattering (NPLS) technique. The computational results predicted by the SST k -ω turbulence model show better agreement with the experimental data. But the small-scale turbulence structures are not captured accurately by these turbulence models. The convoluted shear layer shed from trailing edge is stretched and rotated by the large-scale streamwise vortices, forming an unstable 'pinching-off' structure, which increases the interfacial area. And at the interface of two streams, a large number of small-scale turbulence structures are formed, which contribute a lot to the mixing enhancement along with the increased interfacial area. The streamwise vorticity decays more rapidly with the decrease of velocity ratio and total pressure ratio of two streams. The scalar thickness which reflects the mixing rate of two streams increases with the decreasing velocity ratio and total pressure ratio.

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Section: Introductionmentioning

confidence: 99%

Experimental and numerical study of mixing characteristics of a rectangular lobed mixer in supersonic flow

Feng¹,

Shen²,

Wang

et al. 2015

Aeronaut.j.

View full text Add to dashboard Cite

show abstract

“…While the mechanism for increasing mixing of a lobed forced mixer nozzle was investigated, new computational and experimental methods were also applied for the lobed forced mixer nozzle. Ooba et al 4 used LES (large eddy simulation) to simulate the flow field of a lobed mixer and the results proved that LES could predict mixing characteristics of a lobed mixer. Cooper et al 5 applied different two‐equation turbulent models for computing the flow field of a lobed mixer and found that the outcome produced with a realizable k–ϵ turbulent model was the most consistent with experiment data.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of mixing length on performance of lobed forced mixer nozzles

Xie

Liu

2011

Heat Trans. Asian Res.

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Geometric models of a lobed mixer nozzle with variation of mixing length are created and corresponding flow fields are simulated using a steady Reynolds Averaged Navier-Stokes (RANS) equation with realizable k-ε turbulence model. The numerical simulation results show that the mixing length of the nozzle has a relatively great influence on the development of streamwise vortices and the effective range for streamwise vortices to intensify mixing is about 0.5D distance from the lobe trailing edge. The change of mixing length has little effect on the thermal mixing efficiency. As for the total pressure recovery coefficient, the shorter the mixing length, the sharper the total pressure recovery coefficient curve. On the nozzle exit section, the thermal mixing efficiency increases at first and then slightly declines, and the total pressure recovery efficiency changes little as the mixing length increases. In addition, the thrust coefficient has some small relationship with the mixing length. The thrust coefficient increases in waves as the mixing length increases and the difference between the maximum and the minimum values is slightly less than 1% when the mixing length increases from 0.4D to D.

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“…While the mechanism for increasing mixing of the lobed mixer was investigated, new numerical simulations and experimental methods were also applied. Ooba et al [5] employed the large eddy simulation (LES) method to simulate the flow field of the lobed mixer, and the results demonstrated that LES could correctly predict the flow field of the lobed mixer, especially the streamwise vortices. Hu et al [6] used dual‐plane stereoscopic PIV (DP‐SPIV) to simultaneously measure the velocity (all three components) fields of the lobed mixer/nozzle and obtained the instantaneous and time‐averaged structure of streamwise vortices.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of lobe spacing ratio on performance of forced mixer nozzle

Xie

Liu

2011

Heat Trans. Asian Res.

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Geometric models of a lobed mixer nozzle with variation of lobe spacing ratios are created and the corresponding flow fields are simulated using a steady Reynolds Averaged Navier-Stokes (RANS) equation with a realizable k-ε turbulence model and standard wall function. According to the numerical simulation results, the spacing ratio has a large influence on the shape of streamwise vortices, but a relatively small effect on the streamwise vorticity field at the lobe exit. Therefore, at the initial part of mixing, a change of spacing ratio has little effect on the thermal mixing efficiency and the total pressure recovery coefficient. In addition, the thermal mixing efficiency increases sharply at the initial part, and near the nozzle exit it approaches some constant. The development of the total pressure recovery coefficient is totally reverse to the thermal mixing efficiency. It falls rapidly at the beginning. Then the rate of descent gradually slows down, and approaches some constant. At the nozzle exit cross-section, the thermal mixing efficiency ascends and the total pressure recovery efficiency reduces as the spacing ratio increases. Besides, the thrust coefficient has little relationship to the spacing ratio, with a variation smaller than 0.01 when the spacing ratio increases from 4.87 to 0.497.

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Large eddy simulation analysis of a 18-lobe convoluted mixer nozzle

Cited by 8 publications

References 5 publications

Experimental and numerical study of mixing characteristics of a rectangular lobed mixer in supersonic flow

Experimental and numerical study of mixing characteristics of a rectangular lobed mixer in supersonic flow

Numerical investigation of mixing length on performance of lobed forced mixer nozzles

Numerical investigation of lobe spacing ratio on performance of forced mixer nozzle

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