A non-linear k-epsilon model for turbulent shear flows

Shih, Tsan‐Hsing; Liu, Nan-Suey; Chen, Kuo-Huey

doi:10.2514/6.1998-3983

Cited by 23 publications

(16 citation statements)

References 8 publications

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“…For low Mach number compressible flow, a preconditioning is applied to the governing equations, and the solution is advanced temporally by a so-called "dual-timestep" approach, in which the Runge-Kutta scheme is used for the "inner" iteration. The turbulence model used in the present work is a cubic non-linear k-epsilon model [5] with low Reynolds number wall integration. This turbulence model is reported [5] to capture the recirculation zones and their structures with more accuracy, relative to the standard k-epsilon model.…”

Section: Computational Methodmentioning

confidence: 99%

“…The turbulence model used in the present work is a cubic non-linear k-epsilon model [5] with low Reynolds number wall integration. This turbulence model is reported [5] to capture the recirculation zones and their structures with more accuracy, relative to the standard k-epsilon model. A description of the solver and some benchmark test cases can be found in Refs.…”

Section: Computational Methodmentioning

confidence: 99%

“…Turbulence is modeled by a cubic non-linear k-epsilon model with low Reynolds number wall integration [5]. The chemistryturbulence interactions are represented by the eddy-dissipation combustion model of Magnussen and Hjertager [8], where combustion rate is assumed to be controlled by the turbulence mixing rate of the reactants.…”

Section: Experimental Setup and The Geometrymentioning

confidence: 99%

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Numerical Prediction of Non-Reacting and Reacting Flow in a Model Gas Turbine Combustor

Davoudzadeh

Liu

2004

Volume 1: Turbo Expo 2004

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The three-dimensional, viscous, turbulent, reacting and non-reacting flow characteristics of a model gas turbine combustor operating on air/methane are simulated via an unstructured and massively parallel Reynolds-Averaged Navier-Stokes (RANS) code. This serves to demonstrate the capabilities of the code for design and analysis of real combustor engines. The effects of some design features of combustors are examined. In addition, the computed results are validated against experimental data. The numerical model encompasses the whole experimental flow passage, including the flow development sections for the air annulus and the fuel pipe, twelve channel air and fuel swirlers, the combustion chamber, and the tail pipe. A cubic non-linear low-Reynolds number K-e turbulence model is used to model turbulence, whereas the eddy-breakup model of Magnussen and Hjertager is used to account for the turbulence combustion interaction. Several RANS calculations are performed to determine the effects of the geometrical features of the combustor, and of the grid resolution on the flow field. The final grid is an all-hexahedron grid containing approximately two and one half million elements. To provide an inlet condition to the main combustion chamber, consistent with the experimental data, flow swirlers are adjusted along the flow delivery inlet passage. Fine details of the complex flow structure such as helicalring vortices, recirculation zones and vortex cores are well captured by the simulation. Consistent with the experimental results, the computational model predicts a major recirculation zone in the central region immediately downstream of the fuel nozzle, a second recirculation zone in the upstream corner of the combustion chamber, and a lifted flame. Further, the computed results predict the experimental data with reasonable accuracy for both the cold flow and for the reacting flow. It is also shown that small changes to the geometry can have noticeable effects on the combustor flowfield.

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Section: Computational Methodmentioning

confidence: 99%

Section: Computational Methodmentioning

confidence: 99%

Section: Experimental Setup and The Geometrymentioning

confidence: 99%

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Numerical Prediction of Non-Reacting and Reacting Flow in a Model Gas Turbine Combustor

Davoudzadeh

Liu

2004

Volume 1: Turbo Expo 2004

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“…One is the National Combustion Code (NCC) developed at NASA GRC for turbulent reacting flows in propulsion systems. The subscale mode used in NCC is a two-equation K-( model evolved from its parent RANS models [3][4][5][6]. The simulations of the C4 configuration of a LDI research combustor were performed using the NCC code.…”

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confidence: 99%

Modeling of Internal Reacting Flows and External Static Stall Flows Using RANS and PRNS

Shih

Liu²

2007

Flow Turbulence Combust

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The reacting flow in a research lean direct injection (LDI) hydrogen combustor and the static stall of NACA0012 airfoil were simulated using both Reynolds averaged Navier-Stokes (RANS) and partially resolved numerical simulation (PRNS) approaches. The concept and the main features of the PRNS approach are briefly described. The PRNS basic equations are grid independent or grid invariant; the subscale models are a dynamic equation system. We consider PRNS as an engineering tool for the very large eddy simulation of complex turbulent flows. Two CFD codes, NCC and Wind-US, with two different subscale models (i.e. two-and one-transport equation models, respectively) are used in the presented PRNS simulations. Based on the comparisons with available experimental data, the numerical results indicate that the PRNS subscale models seem to be able to capture important large scale turbulent structures and to improve the quality of numerical simulations while keeping a relatively low cost comparable to the unsteady RANS simulations.

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“…A short summary of the features of NCC pertaining to this paper are: the use of unstructured grids, 1 massively parallel computingwith almost perfectly linear scalability, 2 a dynamic wall function with the effect of adverse pressure gradient, 3 low Reynolds number wall treatment, 4 and a cubic nonlinear k-epsilon turbulence model. 5,6 The combination of these features is usually not available in other CFD codes and gives the NCC an advantage when computing recirculating turbulent flows. These features need to be validated, before the NCC is accepted as a design tool.…”

mentioning

confidence: 99%

Towards accurate prediction of turbulent, three-dimensional, recirculating flows with the NCC

Iannetti

Tacina

Jeng

2001

39th Aerospace Sciences Meeting and Exhibit

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A non-linear k-epsilon model for turbulent shear flows

Cited by 23 publications

References 8 publications

Numerical Prediction of Non-Reacting and Reacting Flow in a Model Gas Turbine Combustor

Numerical Prediction of Non-Reacting and Reacting Flow in a Model Gas Turbine Combustor

Modeling of Internal Reacting Flows and External Static Stall Flows Using RANS and PRNS

Towards accurate prediction of turbulent, three-dimensional, recirculating flows with the NCC

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