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| 1 | Numerical study of methane/air jet flame in vitiated co-flow using tabulated detailed chemistry显示文摘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 models.Results show that the different range of predicted reaction rates is mainly responsible for their different performances in large eddy simulation(LES)studies.In 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 progress.Compared 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 height.Also the results indicate that the variance of reaction progress plays an important role in predicting the flame lifted height. | HAN Chao ZHANG Pei YE TaoHong CHEN YiLiang | 2014 | Science China(Technological Sciences)2014，57，9： | 7 |
| 2 | Hydrogen production by reforming methane in a corona inducing dielectric barrier discharge and catalyst hybrid reactor显示文摘A novel corona inducing dielectric barrier discharge(CIDBD) and catalyst hybrid reactor was developed for reforming methane. This corona inducing technique allows dielectric barrier discharge(DBD) to occur uniformly in a large gap at relatively low applied voltage.Hydrogen production by reforming methane with steam and air was investigated with the hybrid reactor under atmospheric pressure and temperatures below 600°C.The effects of input power,O2/C molar ratio and preheat temperature on methane conversion and hydrogen selectivity were investigated experimentally.It was found that higher methane conversions were obtained at higher discharge power,and methane conversion increased significantly with input power less than 50 W;the optimized molar ratio of O2/C was 0.6 to obtain the highest hydrogen selectivity(112%);under the synergy of dielectric barrier discharge and catalyst,methane conversion was close to the thermodynamic equilibrium conversion rate. | ZHOU ZhiPeng ZHANG JiMin YE TaoHong ZHAO PingHui XIA WeiDong | 2011 | Chinese Science Bulletin2011，56，20： | 6 |
| 3 | Large eddy simulation of hydrogen/air scramjet combustion using tabulated thermo-chemistry approach显示文摘Large eddy simulations(LES) have been performed to investigate the flow and combustion fields in the scramjet of the German Aerospace Center(DLR). Turbulent combustion is modeled by the tabulated thermo-chemistry approach in combination with the presumed probability density function(PDF). A b-function is used to model the distribution of the mixture fraction, while two different PDFs, d-function(Model I) and b-function(Model II), are applied to model the reaction progress. Temperature is obtained by solving filtered energy transport equation and the reaction rate of the progress variable is rescaled by pressure to consider the effects of compressibility. The adaptive mesh refinement(AMR) technique is used to properly capture shock waves,boundary layers, shear layers and flame structures. Statistical results of temperature and velocity predicted by Model II show better accuracy than that predicted by Model I. The results of scatter points and mixture fraction-conditional variables indicate the significant differences between Model I and Model II. It is concluded that second moment information in the presumed PDF of the reaction progress is very important in the simulation of supersonic combustion. It is also found that an unstable flame with extinction and ignition develops in the shear layers of bluff body and a fuelrich partially premixed flame stabilizes in the central recirculation bubble. | Cao Changmin Ye Taohong Zhao Majie | 2015 | Chinese Journal of Aeronautics2015，28，5： | 5 |
| 4 | Large eddy simulation of unconfined turbulent swirling flow显示文摘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. | ZHANG HongDa HAN Chao YE TaoHong ZHANG JiMin CHEN YiLiang | 2015 | Science China(Technological Sciences)2015，58，10： | 5 |
| 5 | Study of the mechanisms of the flame propagation and stabilization in porous media显示文摘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. | ZHAO PingHui YE TaoHong JIANG Hai CHEN YiLiang | 2008 | Science China(Technological Sciences)2008，51，7： | 3 |
| 6 | Numerical investigation on hydrogen production by CH_4-Rich combustion in an alumina foam显示文摘The two-phase volume-averaged model with the detailed chemistry reaction mechanism GRI 3.0 was adopted in the quasi-steady-state simulation of hydrogen production by CH4-rich filtration combustion in an alumina foam under fully developed conditions. The relations among the combustion wave velocity, the inlet gas velocity and the equivalence ratio were discussed, and their influences on the distributions of temperature and species in the alumina foam and on H2 yield, CH4 conversion, H2 selectivity and CO selectivity were analyzed in detail. The results show that the combustion wave velocity increases with the increase of equivalence ratio or inlet gas velocity. The H2 yield exceeded 50% with equivalence ratio between 2.0 and 3.0 and combustion wave velocity larger than 0.4 mm/s. The H2 selectivity exceeded 50% with equivalence ratio larger than 2.0 and CO selectivity exceeded 80% with equivalence ratio between 1.8 and 2.0 and combustion wave velocity larger than 0.4 mm/s. | ZHAO PingHui, YE TaoHong, ZHU MinMing, JIANG Hai & CHEN YiLiang Thermal Science & Energy Engineering Department, University of Science & Technology of China, Hefei 230027, China | 2009 | Science China(Technological Sciences)2009，52，10： | 3 |
| 7 | Continuum-based slip model and its validity for micro-channel flows显示文摘In this paper, the low Mach number he- lium and nitrogen flows in micro-channels are inves- tigated numerically with variations of inlet to outlet pressure ratios, aspect ratios, out pressures and fluid mediums by using different continuum-based slip models. Theoretical solutions based on perturbation expansions of the Navier-Stokes equations have been developed under different order slip conditions. The validity of slip models has been examined by the corresponding experiments and the DSMC method at different Knudsen numbers. Simulations have shown good predictions of the compressibility, rarefaction and thermal creep effects on micro-channel flows with the present slip models. The higher order slip models relatively decrease the rarefaction effects comparing with a first-order slip model. Both of the Knudsen number and the Reynolds number have been identified as key parameters, which govern the rarefaction effects and thermal creep effects, respec- tively. The present slip models have been also dem- onstrated to be appropriate for micro-channel nitro- gen flows with the Knudsen number less than 0.15, and the higher order slip conditions improve the Na- vier-Stokes predictions in the slip flow regime with Kn<0.08. However, the continuum-based slip models significantly under-predict the rarefaction effects in the transitional flow regime as the Knudsen number exceeds 0.2. | ZHANG Genxuan LIU Minghou ZHANG Xianfeng YE Taohong CHEN Yiliang WANG Lu | 2006 | Chinese Science Bulletin2006，51，9： | 3 |
| 8 | A novel method for chemistry tabulation of strained premixed/stratified flames based on principal component analysis显示文摘The principal component analysis(PCA) is used to analyze the high dimensional chemistry data of laminar premixed/stratified flames under strain effects.The first few principal components(PCs) with larger contribution ratios are chosen as the tabulated 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 tabulated 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. | Peng TANG Hongda ZHANG Taohong YE Zhou YU Zhaoyang XIA | 2018 | Applied Mathematics and Mechanics(English Edition)2018，39，6： | 3 |
| 9 | Calibration of a new very large eddy simulation(VLES)methodology for turbulent flow simulation显示文摘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 k-ω model and applications were conducted for fully developed turbulent channel flow at Reτ = 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. | HAN XingSi YE TaoHong CHEN YiLiang | 2012 | Science China(Physics,Mechanics & Astronomy)2012，55，10： | 2 |
| 10 | A new compressibility modification k-ε turbulence model with shock unsteadiness effect显示文摘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 flows.The 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 rate.Sarkar's correction models were employed accounting for the dilatational compressibility effects in the new model.Two types of flows,the free supersonic mixing layers and complex supersonic flow with transverse injection were simulated with different flow conditions.Comparisons 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 predictions.On 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 number.Due 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 forecast.The flow separation was stronger,which was the primary modification effect of the new model.Predictions accord with experimental results even in strong separation flows. | HAN XingSi YE TaoHong ZHU MinMing CHEN YiLiang | 2008 | Chinese Science Bulletin2008，53，24： | 2 |
| 11 | Large eddy simulation of turbulent premixed piloted flame using artificial thickened flame model coupled with tabulated chemistry显示文摘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 F3.More satisfactory results obtained by the dynamic model indicate that it can preserve the premixed flame propagation characteristics better. | Zhou YU Hongda ZHANG Taohong YE Minming ZHU | 2018 | Applied Mathematics and Mechanics(English Edition)2018，39，9： | 1 |
| 12 | Large eddy simulation of turbulent premixed and stratified combustion using flame surface density model coupled with tabulation method显示文摘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 turbulence.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. | Zhou YU Hongda ZHANG Taohong YE Minming ZHU | 2018 | Applied Mathematics and Mechanics(English Edition)2018，39，12： | 1 |
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