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turbulence model performance for ventilation components pressure losses

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Building Simulation 2022年第3期15卷 389-399页

作者： Karsten Tawackolian Martin Kriegel Hermann-Rietschel-Institut EnergyComfort&Health in BuildingsTU BerlinGermany

This study looks to find a suitable turbulence model for calculating pressure losses of ventilation *** building ventilation,the most relevant Reynolds number range is between 3×10^(4) and 6×10^(5),depending on the duct dimensions and airflow *** loss coefficients can increase considerably for some components at Reynolds numbers below 2×10^(5).An initial survey of popular turbulence models was conducted for a selected test case of a bend with such a strong Reynolds number *** of the turbulence models failed in reproducing this dependence and predicted curve progressions that were too flat and only applicable for higher Reynolds *** effects near walls played an important role in the present *** turbulence modelling,near-wall damping functions are used to account for this influence.A model that implements near-wall modelling is the lag elliptic blending k-ε*** model gave reasonable predictions for pressure loss coefficients at lower Reynolds *** example is the low Reynolds number k-εturbulence model of Wilcox(LRN).The modification uses damping functions and was initially developed for simulating profiles such as aircraft *** has not been widely used for internal flows such as air duct *** on selected reference cases,the three closure coefficients of the LRN model were adapted in this work to simulate ventilation *** predictions were obtained with new coefficients(LRNM model).This underlined that low Reynolds number effects are relevant in ventilation ductworks and give first insights for suitable turbulence models for this *** the lag elliptic blending model and the modified LRNM model predicted the pressure losses relatively well for the test case where the other tested models failed.

关键词： HVAC ductwork CFD simulation turbulence model model calibration

A new simpler rotation/curvature correction method for Spalart-Allmaras turbulence model

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Chinese Journal of Aeronautics 2013年第2期26卷 326-333页

作者： Zhang Qiang Yang Yong National Key Laboratory of Science and Techniques on Aerodynamic Design and Research Northwestern Polytechnical University

A new and much simpler rotation and curvature effects factor, which takes the form of Richardson number suggested by Hellsten originally for SST k-ω model, is presented for Spalart and Shur＇s rotation and curvature correction in the context of Spalart-Allmaras （SA） turbulence model. The new factor excludes the Lagrangian derivative of the strain rate tensor that exists in the SARC model, resulting in a simple, efficient and easy-to-implement approach for SA turbulence model （denoted as SARCM） to account for the effects of system rotation and curvature, techniquely. And then the SARCM is tested through turbulent curved wall flows： one is the flow over a zeropressure-gradient curved wall and the other is the channel flow in a duct with a U-turn. Predictions of the SARCM model are compared with experimental data and with the results obtained using original SA and SARC models. The numerical results show that SARCM can predict the rotation-curvature effects as accurately as SARC, but considerably more efficiently. Additionally, the accuracy of SARCM might strongly depend on the rotation-curvature model constants. Suggesting values for those constants are given, after some trials and errors.

关键词： Accuracy Computation Curvature Improvement Robust Rotation Strain rate tensor turbulence model

Effect of Time Step Size and turbulence model on the Open Water Hydrodynamic Performance Prediction of Contra-Rotating Propellers

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China Ocean Engineering 2013年第2期27卷 193-204页

作者：王展智熊鹰 College of Naval Architecture and Power Naval University of Engineering

A growing interest has been devoted to the contra-rotating propellers （CRPs） due to their high propulsive efficiency, torque balance, low fuel consumption, low cavitations, low noise performance and low hull vibration. Compared with the single-screw system, it is more difficult for the open water performance prediction because forward and aft propellers interact with each other and generate a more complicated flow field around the CRPs system. The current work focuses on the open water performance prediction of contra-rotating propellers by RANS and sliding mesh method considering the effect of computational time step size and turbulence model. The validation study has been performed on two sets of contra-rotating propellers developed by David W Taylor Naval Ship R ＆ D center. Compared with the experimental data, it shows that RANS with sliding mesh method and SST k-ω turbulence model has a good precision in the open water performance prediction of contra-rotating propellers, and small time step size can improve the level of accuracy for CRPs with the same blade number of forward and aft propellers, while a relatively large time step size is a better choice for CRPs with different blade numbers.

关键词： contra-rotating propeller open water performance RANS time step size turbulence model

Computational Research on Rotating Channel by a Modified Anisotropic turbulence model

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Journal of Thermal Science 2011年第5期20卷 385-393页

作者： Jianqin Zhu Zhi Tao Chaoqun Nie Institute of Engineering Thermophysics Chinese Academy of Science Beijing 100190 China National Key Lab. on Aero-Engines School of Jet Propulsion Beihang University Beijing 100191.China

Based on the simplified format of the Reynolds stress equations, a fire-new rotational-modification method for the anisotropic turbulence model has been presented. A three-dimensional Navier-Stokes code with this new rotational modified k-ω turbulence models （β=0.1 and β=1） and the standard k-ω turbulence model have been used for the prediction of flow and heat transfer characteristics in a rotating smooth square channel. The Reynolds number Re based on the inlet velocity of the cooling air and hydraulic diameter is 6000 .The rotating speed are 300, 600, 900, 1200rpm respectively. The calculations results of using three turbulence models have been compared with the experimental data. The research results show that （1） the rotational modification coefficient Rf13 used in the new anisotropic k-ω model would increased/decreased the predictions of heat transfer on the trailing surface/leading surface compared to the standard k-ω model. And this tendency would be increased with the increased ft. （2） The simulation performance of the standard k-ω model was well on the leading surface. However, on the trailing surface it under-predicted the heat transfer at high rotating speed. （3） The calculation results of the new anisotropic k-ω model with β=0.1 proposed by the present paper agreed well with experimental data, both on the leading and trailing surfaces. Besides, compared to 1, 0.1 is a more appropriate magnitude of βat conditions in the present paper.

关键词： anisotropy turbulence model rotation heat transfer

A dual-eddy EMMS-based turbulence model for laminar-turbulent transition prediction

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Particuology 2021年第5期19卷 285-298页

作者： Shuyu Guo Limin Wang State Key Laboratory of Multiphase Complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China School of Chemical Engineering University of Chinese Academy of SciencesBeijing 100049China Innovation Academy for Green Manufacture Chinese Academy of SciencesBeijing 100190China

turbulence is a century-old physics problem,and the prediction of laminar-turbulent transition remains a major challenge in computational fluid dynamics(CFD).This paper proposes a new conceptual multiscale-structure flow system consisting of a nonturbulent part and two types of turbulent eddies with different *** stability criterion for turbulent transition flows,based on the principle of compromise-in-competition between viscosity and inertia,is used to obtain model *** multiscale-structure concept and stability criterion are the characteristics of the dual-eddy energy-minimization multiscale(EMMS)-based turbulence *** solved heterogeneous structure parameters and energy dissipation rate are analyzed,which reveal the laminar-turbulent transition *** validate the dual-eddy EMMS-based turbulence model,three benchmark problems,namely,the transitional flows over the flat plate boundary layer with zero pressure gradient,NACA0012,and Aerospatiale-A airfoils,were *** simulation was performed by combining the optimized results from the proposed model with the equations of the well-known κ-ω shear stress transfer(SST)turbulence *** numerical results show that the dual-eddy EMMS-based turbulence model improves the prediction in the laminar-turbulent transition *** demonstrates the soundness of using the multiscale-structure concept in turbulent flows to establish the turbulence transition model by considering the principle of compromise-in-competition between viscosity and inertia.

关键词： Turbulent flows Laminar-turbulent transition EMMS turbulence model Multiscale structure

PARAMETER ESTIMATION OF ENGINEERING turbulence model

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Acta Mechanica Sinica 2001年第4期17卷 302-309页

作者：钱炜棋蔡金狮 China Aerodynamics Research&Development Center Mianyang 621000 China

A parameter estimation algorithm is introduced and used to determine the parameters in the standard k-epsilon two equation turbulence model (SKE). It can be found from the estimation results that although the parameter estimation method is an effective method to determine model parameters, it is. difficult to obtain a set of parameters for SKE to suit all kinds of separated flow and a modification of the turbulence model structure should be considered. So, a new nonlinear k-e two-equation model (NNKE) is put forward in this paper and the corresponding parameter estimation technique is applied to determine the model parameters. By implementing the NNKE to solve some engineering turbulent flows, it is shown that NNKE is more accurate and versatile than SKE. Thus, the success of NNKE implies that the parameter estimation technique may have a bright prospect in engineering turbulence model research.

关键词： turbulence model parameter estimation k-epsilon two-equation model

A three-equation turbulence model for high-speed flows

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Science China(Technological Sciences) 2013年第4期56卷 803-811页

作者： LIU JingYuan Aircraft Engineering College Nanchang Hangkong University

Adding a new equation to the two-equation K-turbulence model framework,this paper proposed a three-equation turbulence model to determine the density variance for high-speed aero-optics and high-speed compressible turbulent *** were performed with the new model for supersonic and hypersonic flat-plate turbulent boundary layer and hypersonic ramp *** results showed that the prediction with the present model agrees well with the experimental data and is significantly better than the Lutz's model in predicting the density variance for the flat-plate ***,the present model can produce more accurate skin pressure and skin heat flux distributions than the original K-model in simulating hypersonic compression ramp flows with separation and reattachment and shock/boundary layer *** introducing a variety of ad hoc wall damping and wall-reflection terms,the proposed three-equation turbulence model is applicable to highspeed aero-optics and turbulent flows of real vehicles of complex configuration.

关键词： high speed turbulence model density variance aero-optics numerical simulation heat flux separation

Numerical Evaluation of Two k-εturbulence model for Predicting Flow and Solidification in Continuous Casting Slab

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Journal of Iron and Steel Research International 2003年第2期10卷 10-16页

作者： LIU He-ping GAN Yong QIU Sheng-tao Central Iron and Steel Research Institute

A steady three-dimensional fluid flow and solidification model was built based on CFD software by high-Reynolds-number and Lam-Bremhorst low-Reynolds-number k-ε *** the simulation,the fixed-grid enthalpy-porosity technique was used to represent the solidification,and Darcy law was adopted to simulate the flow in mushy *** prediction for steel flow and solidification was evaluated by the comparison of two turbulence *** is found that both Lam-Bremhorst low-Reynolds-number and high-Reynolds-number k-ε models predict the same trend of the steel flow and temperature ***,due to the effect of turbulent flow on heat transfer,the low-Reynolds-number turbulence model predicts longer penetration depth of molten steel in sub-mold region,less shell growth and higher shell surface temperature at the narrow face compared with standard k-ε model.

关键词： continuous slab caster solidification steel flow turbulence model numerical simulation

Development of the modified k-ε turbulence model of power-law fluid for engineering applications

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Science China(Technological Sciences) 2012年第1期55卷 276-284页

作者： RO Kyoungchul RYOU HongSun Department of Mechanical Engineering Chung-Ang University

In the present study, a high Reynolds number version of a turbulence model was proposed by using drag reduction to analyze the turbulent flows of power-law fluid for engineering applications. In order to determine the model constants in the constitutive equation, numerical simulation was conducted under the same conditions that were applied to obtain the experiment re- suits and previous turbulence models. For validation of the modified turbulence model, numerical simulations were performed for power-law fluids of different viscosities. The results of the modified k-ε turbulence model showed better agreement with the experimental results than those of the standard k-ε turbulence model. In addition, computation time and computer resource of the modified k-ε turbulence model were reduced by about one third as compared to the low Reynolds number model for power-law fluids.

关键词： power-law fluid turbulent flow drag reduction turbulence model computational fluid dynamics(CFD)