检索结果-南通市图书馆

Calibration of a new very large eddy simulation(VLES)methodology for turbulent flow simulation

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2012年第10期55卷 1905-1914页

作者： HAN XingSi ye taohong CHEN YiLiang Division of Fluid Dynamics Department of Applied Mechanics Chalmers University of Technology Gothenburg SE-41296 Sweden Department of Thermal Science and Energy Engineering University of Science and Technology of China Hefei 230027 China

Following the idea of Speziale＇s Very Large Eddy Simulation （VLES） method, a new unified hybrid simulation approach was proposed which can change seamlessly from RANS （Reynolds-Averaged Navier-Stokes） to LES （Large Eddy Simulation） method depending on the numerical resolution. The model constants were calibrated in accordance with other hybrid methods. Besides being able to approach the two limits of RANS and LES, the new model also provides a proper VLES mode between the two limits, and thus can be used for a wide range of mesh resolutions. Also RANS simulation can be recovered near the wall which is similar to the Detached Eddy Simulation （DES） concept. This new methodology was implemented into Wilcox＇s κ- ω model and applications were conducted for fully developed turbulent channel flow at ReT = 395 and turbulent flow past a square cylinder at Re = 22000. Results were compared with LES predictions and other studies. The new method is found to be quite efficient in resolving large flow structures, and can predict satisfactory results on relative coarse mesh.

关键词： hybrid RANS-LES method Very Large Eddy Simulation (VLES) channel flow flow past a square cylinder

Large eddy simulation of turbulent premixed piloted flame using artificial thickened flame model coupled with tabulated chemistry

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2018年第9期39卷 1277-1294页

作者： Zhou YU Hongda ZHANG taohong ye Minming ZHU Department of Thermal Science and Energy Engineering University of Science and Technology of China Shenyang Engine Research Institute Aero Engine (Group) Corporation of China

A sub-grid scale(SGS) combustion model, which combines the artificial thickened flame(ATF) model with the flamelet generated manifold(FGM) tabulation method, is proposed. Based on the analysis of laminar flame structures, two self-contained flame sensors are used to track the diffusion and reaction processes with different spatial scales in the flame front, respectively. The dynamic formulation for the proposed SGS combustion model is also performed. Large eddy simulations(LESs) of Bunsen flame F3 are used to evaluate the different SGS combustion models. The results show that the proposed SGS model has the ability in predicting the distributions of temperature and velocity reasonably, while the predictions for the distributions of some species need further improvement. The snapshots of instantaneous normalized progress variables reveal that the flame is more remarkably and severely wrinkled at the flame tip for flame *** satisfactory results obtained by the dynamic model indicate that it can preserve the premixed flame propagation characteristics better.

关键词： large eddy simulation(LES) artificial thickened flame model tabulation dynamic modeling flame sensor

Large eddy simulation of turbulent premixed and stratified combustion using flame surface density model coupled with tabulation method

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2018年第12期39卷 1719-1736页

Large eddy simulations(LESs) are performed to investigate the Cambridge premixed and stratified flames, SwB1 and SwB5, respectively. The flame surface density(FSD) model incorporated with two different wrinkling factor models, i.e., the Muppala and Charlette2 wrinkling factor models, is used to describe combustion/turbulence interaction, and the flamelet generated manifolds(FGM) method is employed to determine major scalars. This coupled sub-grid scale(SGS) combustion model is named as the FSD-FGM model. The FGM method can provide the detailed species in the flame which cannot be obtained from the origin FSD model. The LES results show that the FSD-FGM model has the ability of describing flame propagation, especially for stratified flames. The Charlette2 wrinkling factor model performs better than the Muppala wrinkling factor model in predicting the flame surface area change by the *** combustion characteristics are analyzed in detail by the flame index and probability distributions of the equivalence ratio and the orientation angle, which confirms that for the investigated stratified flame, the dominant combustion modes in the upstream and downstream regions are the premixed mode and the back-supported mode, respectively.

关键词： large eddy simulation(LES) flame surface density(FSD) model tabulation premixed combustion stratified combustion

Numerical study of methane/air jet flame in vitiated co-flow using tabulated detailed chemistry

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2014年第9期57卷 1750-1760页

作者： HAN Chao ZHANG Pei ye taohong CHEN YiLiang Department of Thermal Science and Energy Engineering University of Science and Technology of China

Two different combustion models,the autoignition(AI)model and flamelet/progress variable(FPV)model,have been applied to study the auto-ignition process of methane/air jet flame in vitiated co-flow.A priori study was conducted to test the validity of the two *** show that the different range of predicted reaction rates is mainly responsible for their different performances in large eddy simulation(LES)*** this paper,beta PDF was used to model the mixture fraction distribution,while two different shapes of PDF,delta function and beta function,were applied for the reaction *** to the FPV model,the AI model combined with beta function for reaction progress could capture the auto-ignition process and predict the exact lifted *** the results indicate that the variance of reaction progress plays an important role in predicting the flame lifted height.

关键词： large eddy simulation flamelet/progress variables autoignition vitiated co-flow flame

Large eddy simulation of unconfined turbulent swirling flow

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2015年第10期58卷 1731-1744页

作者： ZHANG HongDa HAN Chao ye taohong ZHANG JiMin CHEN YiLiang Department of Thermal Science and Energy Engineering University of Science and Technology of China

Large eddy simulations(LES) were performed to study the non-reacting flow fields of a Cambridge swirl burner. The dynamic Smagorinsky eddy viscosity model is used as the sub-grid scale turbulence model. Comparisons of experimental data show that the LES results are capable of predicting mean and root-mean-square velocity profiles. The LES results show that the annular swirling flow has a minor impact on the formation of the bluff-body recirculation zone. The vortex structures near the shear layers, visualized by the iso-surface of Q-criterion, display ring structures in non-swirling flow and helical structures in swirling flow near the burner exit. Spectral analysis was employed to predict the occurrence of flow oscillations induced by vortex shedding and precessing vortex core(PVC). In order to extract accurately the unsteady large-scale structures in swirling flow, a three-dimensional proper orthogonal decomposition(POD) method was developed to reconstruct turbulent fluctuating velocity fields. POD analysis reveals that flow fields contain co-existing helical and toroidal shaped coherent structures. The helical structure associated with the PVC is the most energetic dynamic flow structure. The latter toroidal structure associated with vortex shedding has lower energy content which indicates that it is a secondary structure.

关键词： Cambridge swirl burner large eddy simulation proper orthogonal decomposition vortex shedding and breakdown,precessing vortex core

Study of the mechanisms of the flame propagation and stabilization in porous media

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2008年第7期51卷 871-881页

作者： ZHAO PingHui ye taohong JIANG Hai CHEN YiLiang Department of Thermal Science&Energy Engineering University of Science&Technology of ChinaHefei 230027China

The CH4/air premixed gas combustion processes in porous media were numerically studied using the two-temperature reacting fluid model with dispersions and detailed chemical reaction mechanism GRI 3.0. The mechanisms of the propagation and stabilization of submerge flames and surface flames in porous media were illuminated distinctly by considering the magnitude of the terms in the two energy equations, analyzing the sensibility of flame propagation speed to flame location, heat exchange coefficient between gas and solid, thermal conductivity and radiative extinction coefficient of porous media. It was concluded that the propagation mechanism of a submerged flame is similar to that of a free flame with an additional preheat zone and that the surface-flame propagation mechanism in porous media is similar to that of a free flame with heat loss in reaction zone.

关键词： porous media surface flame submerged flame flame propagation speed

A new compressibility modification k-ε turbulence model with shock unsteadiness effect

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 2008年第24期53卷 3798-3807页

作者： HAN XingSi ye taohong ZHU MinMing CHEN YiLiang Department of Thermal Science and Engineering University of Science and Technology of China Hefei 230027 China

A new compressibility modification k-ε model,including shock unsteadiness effect and the previous compressibility modification of pressure dilatation and dilatational dissipation rate,was developed with a simple formulation for numerical simulation in supersonic complex turbulent *** shock unsteadiness effect was modeled by inhibiting turbulent kinetic energy production in the governing equations of turbulent kinetic energy and the turbulent kinetic energy dissipation ***'s correction models were employed accounting for the dilatational compressibility effects in the new *** types of flows,the free supersonic mixing layers and complex supersonic flow with transverse injection were simulated with different flow *** with experimental data of the free supersonic mixing layers showed that the new compressibility modification k-ε model significantly inhibited the excessive growth of turbulent kinetic energy and improved *** the supersonic mixing layer flows,prediction results with the new model were in close agreement with experimental data,accurately predicting the decreasing trend of the mixing layer spreading rate with the increase of the convective Mach *** to the complicated flow field with flow separation,shock unsteadiness modification inhibited excessive growth of the turbulent kinetic energy in shock regions and wider shock regions are predicted,thereby significantly improving results of the flow with a strong separation *** flow separation was stronger,which was the primary modification effect of the new *** accord with experimental results even in strong separation flows.

关键词：可压缩湍流激震变数 k-ε湍流数学模拟

A novel method for chemistry tabulation of strained premixed/stratified flames based on principal component analysis

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2018年第6期39卷 855-866页

作者： Peng TANG Hongda ZHANG taohong ye Zhou YU Zhaoyang XIA Department of Thermal Science and Energy Engineering University of Science and Technology of China School of Mechatronics Engineering Chizhou University Shenyang Engine Research Institute Aero Engine(Group) Corporation of China

The principal component analysis （PCA） is used to analyze the high dimen- sional chemistry data of laminar premixed/stratified flames under strain effects. The first few principal components （PCs） with larger contribution ratios axe chosen as the tabu- lated scalars to build the look-up chemistry table. Prior tests show that strained premixed flame structure can be well reconstructed. To highlight the physical meanings of the tabu- lated scalars in stratified flames, a modified PCA method is developed, where the mixture fraction is used to replace one of the PCs with the highest correlation coefficient. The other two tabulated scalars are then modified with the Schmidt orthogonalization. The modified tabulated scalars not only have clear physical meanings, but also contain passive scalars. The PCA method has good commonality, and can be extended for building the thermo-chemistry table including strain rate effects when different fuels are used.

关键词： premixed flame stratified flame strain rate principal component analysis(PCA) chemistry table

Large eddy simulation on the flow characteristics of an argon thermal plasma jet

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2021年第12期23卷 105-116页

作者： Xu ZHOU Xianhui CHEN taohong ye Minming ZHU School of Engineering Science University of Science and Technology of ChinaHefei 230022People's Republic of China

Large eddy simulations based on the CFD software Open FOAM have been used to study the effect of Reynolds number and turbulence intensity on the flow and mixing characteristics of an argon thermal plasma *** analysis was carried out with respect to four aspects:the average flow field,the instantaneous flow field,turbulence statistical characteristics and the *** was shown that for the argon thermal plasma jet with low Reynolds number,increasing the turbulence intensity will increase the turbulent transport mechanism in the mixing layer rather than in the jet axis,leading to the faster development of *** effect of the turbulent transport mechanism increases with increasing Reynolds ***,the characteristics of flow and mixing are not affected by turbulence intensity for high Reynolds number *** was also found that the mean axial velocity and mean temperature in the axis of the turbulent thermal plasma jet satisfy the self-similarity aspects *** addition,decay constant K is 1.25,which is much smaller than that(5.7-6.1)of the turbulent cold gas jet and has nothing to do with the Reynolds number or turbulence intensity in the jet inlet.

关键词： thermal plasma jet mixing layer characteristics Reynolds number turbulence intensity large eddy simulation