Reliable and Accurate Prediction of Three-Dimensional Separation in Asymmetric Diffusers Using Large-Eddy Simulation

Schneider, Hayder; Terzi, Dominic von; Bauer, H.-J.; Rodi, W.

doi:10.1115/1.4001009

Cited by 23 publications

(16 citation statements)

References 7 publications

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“…Methods that account for or even resolve these structures generally fare better. In the same study, Schneider et al (2010) performed large-eddy simulation (LES) with near-wall modelling and obtained results that agreed with the experimental data within their accuracy for both D1 and D2. Good results were also reported for D1 employing both wall-resolving LES and a hybrid RANS/LES method (Jakirlić et al 2010).…”

Section: Introductionsupporting

confidence: 62%

“…Overall, the contribution of the SGS model was relatively small with a time-and volumeaveraged fraction of turbulent to molecular viscosity, ν t /ν, of the order of O(10 −2 ). In contrast to Schneider et al (2010), the present simulations resolve the near-wall region instead of employing a near-wall model. All simulations were performed on the same computational grid with 896 × 128 × 192 cells (22 million).…”

Section: The Numerical Experimentsmentioning

confidence: 81%

“…By scrutinizing the workshop results (Jakirlić et al 2011), one can conclude that the quality of the diffuser predictions increased with the capability of the CFD method to represent the mean secondary vortices (MSVs) in the inflow duct. Schneider et al (2010) demonstrated that Reynolds-averaged Navier-Stokes (RANS) calculations with an eddy-viscosity model yielded qualitatively wrong results. These models cannot reproduce MSVs in the inflow duct.…”

Section: Introductionmentioning

confidence: 98%

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A mechanism for control of turbulent separated flow in rectangular diffusers

et al. 2011

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The turbulent separated flow through an asymmetric diffuser with and without manipulation of incoming turbulence-driven mean secondary vortices (MSVs) from a rectangular duct is investigated by large-eddy simulations. The simulations carried out for two diffuser geometries reveal that by introducing a small amount of meanflow kinetic energy via the MSVs into the flow, the complex three-dimensional separation behaviour and pressure recovery can be effectively controlled. Manipulated MSVs were found to enhance cross-sectional transport of high-momentum fluid, which determined the location, shape, and size of the separation bubble. The integral effect was a delay or expedition in the onset of separation. This change strongly affected the conversion of mean-flow kinetic energy to pressure, in particular for the front part of the diffuser. In addition, a substantial reduction in total pressure loss could be achieved. The manipulation of the MSVs is an efficient mechanism for performance enhancement in the cases investigated. The results have important implications for both control and statistical modelling of turbulent separated flow in rectangular diffusers.

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Section: Introductionsupporting

confidence: 62%

Section: The Numerical Experimentsmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 98%

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A mechanism for control of turbulent separated flow in rectangular diffusers

et al. 2011

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“…We mention here also the comparable inflow generation of Schneider et al (2010), successfully applied over a channel length of only 3 channel heights. The temporal resolution adopted corresponds to a non-dimensional time step of Dt = 0.0001U bulk /h = 0.01 (normalized by the inlet channel parameters U bulk = 1 m/s and h = 1 cm).…”

Section: Methodsmentioning

confidence: 99%

Numerical and physical aspects in LES and hybrid LES/RANS of turbulent flow separation in a 3-D diffuser

Jakirlić

Kadavelil

Kornhaas

et al. 2010

International Journal of Heat and Fluid Flow

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“…The MRV experimental technique has been validated using high-fidelity numerical simulations such as large eddy simulations (LES) by Schneider et al (2010) and direct numerical simulations (DNS) by Ohlsson et al (2010), which were both compared to the MRV data of Cherry et al (2008). Established experimental techniques such as particle image velocimetry (PIV) have also been used to validate MRV measurements, with excellent agreement between the two techniques (Elkins et al 2009;Coletti et al 2013).…”

Section: Introductionmentioning

confidence: 98%

Comparison of magnetic resonance concentration measurements in water to temperature measurements in compressible air flows

et al. 2014

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Magnetic resonance imaging (MRI) measurements in liquid flows provide highly detailed 3D mean velocity and concentration data in complex turbulent mixing flow applications. The scalar transport analogy is applied to infer the mean temperature distribution in high speed gas flows directly from the MRI concentration measurements in liquid. Compressibility effects on turbulent mixing are known to be weak for simple flows at high subsonic Mach number, and it was not known if this would hold in more complex flows characteristic of practical applications. Furthermore, the MRI measurements are often done at lower Reynolds number than the compressible application, although both are generally done in fully turbulent flows. The hypothesis is that the conclusions from MRI measurements performed in water are transferable to high subsonic Mach number applications. The present experiment is designed to compare stagnation temperature measurements in high speed airflow (M = 0.7) to concentration measurements in an identical water flow apparatus. The flow configuration was a low aspect ratio wall jet with a thick splitter plate producing a 3D complex downstream flow mixing the wall-jet fluid with the mainstream flow. The three-dimensional velocity field is documented using magnetic resonance velocimetry in the water experiment, and the mixing is quantified by measuring the mean concentration distribution of wall-jet fluid marked with dissolved copper sulfate. The airflow experiments are operated with a temperature difference between the main stream and the wall jet. Profiles of the stagnation temperature are measured with a shielded thermocouple probe. The results show excellent agreement between normalized temperature and concentration profiles after correction of the temperature measurements for the effects of energy separation. The agreement is within 1 % near the edges of the mixing layer, which suggests that the mixing characteristics of the large scale turbulence structures are the same in the two flows.

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Reliable and Accurate Prediction of Three-Dimensional Separation in Asymmetric Diffusers Using Large-Eddy Simulation

Cited by 23 publications

References 7 publications

A mechanism for control of turbulent separated flow in rectangular diffusers

A mechanism for control of turbulent separated flow in rectangular diffusers

Numerical and physical aspects in LES and hybrid LES/RANS of turbulent flow separation in a 3-D diffuser

Comparison of magnetic resonance concentration measurements in water to temperature measurements in compressible air flows

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