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An improved large eddy simulation of two-phase flows in a pump impeller

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Acta Mechanica Sinica 2007年第6期23卷 635-643页

作者： Xuelin Tang Fujun Wang yulin wu College of Water Conservancy and Civil Engineering China Agricultural University Beijing 100083 China Department of Thermal Engineering Tsinghua University Beijing 100084 China

An improved large eddy simulation using a dynamic second-order sub-grid-scale （SGS） stress model has been developed to model the governing equations of dense turbulent particle-liquid two-phase flows in a rotating coordinate system, and continuity is conserved by a mass-weighted method to solve the filtered governing equations. In the cur- rent second-order SGS model, the SGS stress is a function of both the resolved strain-rate and rotation-rate tensors, and the model parameters are obtained from the dimensional consistency and the invariants of the strain-rate and the rotation-rate tensors. In the numerical calculation, the finite volume method is used to discretize the governing equations with a staggered grid system. The SIMPLEC algorithm is applied for the solution of the discretized governing equations. Body- fitted coordinates are used to simulate the two-phase flows in complex geometries. Finally the second-order dynamic SGS model is successfully applied to simulate the dense turbu-lent particle-liquid two-phase flows in a centrifugal impeller. The predicted pressure and velocity distributions are in good agreement with experimental results.

关键词： Large eddy simulation Second-order sub-grid-scale stress model Turbulent two-phase flow Pump impeller

An optimization method on runner blades in bulb turbine based on CFD analysis

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Science China(Technological Sciences) 2011年第2期54卷 338-344页

作者： YANG Wei wu yulin LIU ShuHong Institute of Nuclear and New Energy Technology Tsinghua University Beijing 100084 China State Key Laboratory of Hydroscience and Engineering Department of Thermal Engineering Tsinghua University Beijing 100084 China

In this paper an optimization method of the runner blades in a bulb turbine based on CFD analysis is *** the method the main scales of the turbine including guide vane,runner and draft are *** the runner blades are modified based on the present *** the optimization method the runner blade is expressed by spline surface with a gather of coordinate *** B-spline curve is used to keep the modified blades *** order to make the blade optimization simple and ef- ficient,one of the coordinates is fixed and only the angles of the points are changed according to different modification *** main optimization principles based on flow diagnosis are presented *** three principles are all based on the CFD analysis of the internal flow in bulb *** the purpose of method verification,the optimization method is used in a model bulb turbine.A three dimensional steady turbulent computation is carried out through the whole passage including the bulb body,guide vanes,runner and draft tube of the bulb turbine under seven different work *** SST k-ωturbulence model is used during the CFD analysis and the performance of the turbine can be *** runner blade is optimized according to the three optimization principles based on flow *** CFD analysis is conducted again on the optimized turbine and another modification is needed if the new turbine can’t satisfy the required *** of the computational results between the original turbine and an optimized one indicates that the optimization method is practical and does improve the performance of the bulb turbine.

关键词： bulb turbine CFD flow diagnose performance prediction SST k-ω turbulence model B-spline curve

Numerical simulation of pressure fluctuation in Kaplan turbine

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Science China(Technological Sciences) 2008年第8期51卷 1137-1148页

作者： LIU ShuHong SHAO Jie wu ShangFeng wu yulin Department of Thermal Engineering State Key Laboratory of Hydroscience and EngineeringTsinghua UniversityBeijing 100084China

As it is almost impossible to carry out the prototype hydro-turbine experiment be- fore the power plant is built up, rational prediction of pressure fluctuations in the prototype turbine is very important at the design stage. From this viewpoint, we at first treated the unsteady turbulent flow computation based on the modified RNG k-ε turbulence model through the whole flow passage to simulate the pressure fluctuation in a model turbine. Since fair agreement was recognized between the numerical results and the experimental data, this numerical method was applied to simulate the pressure fluctuations in the prototype turbine. From the comparison of them with the model turbine results, it is seen that their qualitative trend of pres- sure fluctuations are similar, but an appreciable difference is observed between the amplitudes of pressure fluctuation of the prototype turbine and that of the model turbine. Though the present findings may be explained by the effect of Reynolds number, further studies are expected for quantitative interpretation. We paid atten- tion to the interaction between the fluid and turbine structure. Adopting a weak fluid-solid coupling method, we studied the pressure fluctuation in the prototype turbine to clarify how the elastic behavior of runner blades influenced the charac- teristics of pressure fluctuation.

关键词： RNG k-ε turbulence model Kaplan turbine pressure fluctuation unsteady flow simulation

Silica supply and diatom blooms in the Jiaozhou Bay, China

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Acta Oceanologica Sinica 2016年第10期35卷 20-27页

作者： SHEN Zhiliang YAO Yun wu yulin Key Laboratory of Marine Ecology and Environmental Sciences Institute of Oceanology Chinese Academy of Sciences Research Center for the Computer and Chemical Engineering Qingdao University of Science and Technology

The variations in nutrients（molar ratios） and chlorophyll a in the Jiaozhou Bay were examined before and after a diatom bloom in a period that lasted from November 2003 to March 2004. Negative relationships between nutrient concentrations, Si/P, Si/N ratios and chlorophyll a content were found during the bloom, which reflected the relationship between nutrient concentrations, phytoplankton biomass and growth. Large increase in nutrient concentrations, particularly SiO_3-Si after the late autumn, is one of major reasons inducing the diatom bloom in winter, and the bloom was finally controlled due to SiO_3-Si depletion by phytoplankton. The bloom was mainly controlled by SiO_3-Si. Before 1998, relatively low level of SiO_3-Si kept ecological balance of eutrophication waters in the Jiaozhou Bay. In recent years, however, human activities have increased SiO_3-Si concentration, which is likely one of the primary cause for the increased diatom blooms in the Jiaozhou Bay. Therefore, it is necessary to control SiO_3-Si concentration in the Jiaozhou Bay.

关键词： nutrient phytoplankton chlorophyll α blooms Si supply Jiaozhou Bay

STUDY ON FLOWS THROUGH CENTRIFUGAL PUMP IMPELLER BY TURBULENT SIMULATION

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Journal of Hydrodynamics 1997年第1期9卷 11-23页

作者： Dai, Jiang wu, yulin Cao, Shuliang Tsinghua Univ Beijing China

A finite volume numerical method is presented for simulating internal turbulent flows on the blade-to-blade surface through a centrifugal pump impeller, in which, a mesh in body-fitted coordinates is generated for the computation. The SIMPLEC algorithm is utilized for solving governing equations of incompressible viscous/turbulent flows through the pump impeller. The K-Ε turbulence model is adopted to describe the turbulent flow process. Some worthwhile simulated results are presented.

关键词： Centrifugal pumps Simulation Turbulence Turbulent flow

PIV measurement on internal instantaneous flows of a centrifugal pump

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Science China(Technological Sciences) 2011年第2期54卷 270-276页

作者： wu yulin LIU ShuHong YUAN HuiJing SHAO Jie State Key Laboratory of Hydro Science and Hydraulic Engineering Department of Thermal Engineering Tsinghua University Beijing 100084 China State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Belting 100871 China

In this paper,the internal flow field in a centrifugal pump working at the design flow rate operating condition has been measured using the particle image velocimetry(PIV)technique with the fluorescent particles and the index-matched fluid *** index-marching fluid with the same refractive index as the transparent material has been prepared and applied in the present test of pump with geometrical complex *** comparison between velocity distributions of PIV results both with and without fluorescent particles,as well as with and without index-marching fluid are conducted to find the *** DES(Detached Eddy Simulation)has been employed to calculate the three-dimensional unsteady turbulent flow in the pump to examine and to certify the PIV measurement *** DES results of instantaneous flow velocity fields agree with PIV test results with fluorescent particles and index-marching *** is necessary to perform the PIV measurement of pumps with fluorescent seeds and index-marching fluid in order to get exact *** experimental results show the distributions of velocity,steamlines,and the principal Reynolds normal stress(PRNS)and the principal Reynolds shear stress(PRSS).

关键词： pump PIV laser induced fluorescence refractive index matched

Nutrient compositions of cultured Thalassiosira rotula and Skeletonema costatum from the Jiaozhou Bay in China

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Acta Oceanologica Sinica 2008年第4期27卷 147-155页

作者： SHEN Zhiliang wu yulin LIU Qun YAO Yun Key Laboratory of Marine Ecology and Environmental Sciences Institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China

Carbon, nitrogen, phosphorus, silicon composition of cultured two different sized phytoplankton common species of Thalazsiosira rotula and Skeletonema costatum from the Jiaozhou Bay were measured. Carbon, nitrogen, phosphorus, silicon contents in cell were obvious higher in T. rotula than in S. costatum, but the percents of nitrogen, phosphorus, sihcon contents in cell dry mass in T. rotula were lower than those in S. costatum. The dry mass concentrations of nitrogen,phosphorus, silicon in S. costatum were much higher than those in T. rotula, particularly silicon, the former was 6. 4 times of the latter, showing that S. costatum could more assimilate these elements. Especially, S. costatum had competitive dominance for assimilating silicon, which is beneficial to its becoming a major dominant species in relative short silicon of the Jiaozhou Bay. There were some differences in numerical value of nutrient ratios both laboratory-cultured phytoplankton and different sized suspended particulates （ mainly phytoplankton） in the Jiaozhou Bay, which was caused by the changes of environment. High contents of carbon, nitrogon and relative low phosporus, sil- icon, high molar ratio of nitrogen to phosphorus （far higher than Redfield value） and low ratio of silicon to phosphorus and silicon to nitrogen （far lower than Redfield values） in the two diatoms and different sized suspended particulates were consistent with those in the seawater. Relative short silicon in the seawater and phytoplankton showed that silicon was possibly affectting phytoplankton growth in the Jiaozhou Bay.

关键词： carbon nitrogen phosphorus,silicon composition Skeletonema costatum Thalazsiosira rotula Jiaozhou Bay

Analysis of Two-Phase Cavitating Flowwith Two-Fluid Model Using Integrated Boltzmann Equations

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Advances in Applied Mathematics and Mechanics 2013年第5期5卷 607-638页

作者： Shuhong Liu yulin wu Yu Xu Hua-Shu Dou State Key Laboratory of Hydro Science and Hydraulic Engineering Tsinghua UniversityBeijing 100084China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100080China Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018ZhejiangChina

In the present work,both computational and experimentalmethods are employed to study the two-phase flow occurring in a model pump *** twofluid model of the two-phase flow has been applied to the simulation of the threedimensional cavitating *** governing equations of the two-phase cavitating flow are derived from the kinetic theory based on the Boltzmann *** isotropic RNG k−ε−kca turbulence model of two-phase flows in the form of cavity number instead of the formof cavity phase volume fraction is *** RNG k−ε−kca turbulence model,that is the RNG k−εturbulence model for the liquid phase combined with the kca model for the cavity phase,is employed to close the governing turbulent equations of the two-phase *** computation of the cavitating flow through a model pump sump has been carried out with this model in three-dimensional *** calculated results have been compared with the data of the PIV *** qualitative agreement has been achievedwhich exhibits the reliability of the numerical simulation model.

关键词： Cavitating flow two-fluidmodel RNG k−ε−kca turbulencemodel Boltzmann equations kinetic theory.

Genotoxicity evaluation of drinking water sources in human peripheral blood lymphocytes using the comet assay

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Journal of Environmental Sciences 2008年第4期20卷 487-491页

作者： wu yulin CHEN Haigang LI Zhaoli SUN Liwei QU Mengmeng LI Mei KONG Zhiming State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University Nanjing 210093 China Jiangsu Institute of Planned Parenthood Research Nanjing 210036 China

The potential harm of organic pollutants in drinking water to human health is widely focused on in the wodd; more and more pollutants with genotoxic substances are released into the aquatic environment. Water source samples were collected from 7 different localities of Nanjing City. The potential genotoxicity of organic extracts from drinking water sources were investigated by means of the comet assay in human peripheral lymphocytes. The results showed that all the organic extracts from all the water source samples could induce DNA damages of human peripheral blood lymphocytes at different levels. A significant difference （P 〈 0.01） was observed when compared with the solvent control, The DNA damage increased with the increase of the dosage of the original water source. Significant differences of DNA damage were observed in different drinking water sources, as shown by the multiple comparisons analysis at the dosage of 100x; the degree of DNA damage treated by Hushu waterworks （at town level） was the most serious, the arbitrary units （AU） was 141.62±6.96, however, that of Shangyuanmen waterworks （at city level） was only 109.64±2.97. The analysis also revealed that the genotoxicity of town＇s water sources was higher than that of the city. The results demonstrated that the comet assay can be successfully applied to the genotoxicity monitoring programs of drinking water sources.

关键词： comet assay drinking water sources genotoxicity human peripheral blood lymphocyte