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Prediction of transition boiling concerning downward facing horizontal surface in confined space using artificial neural network

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Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2009年第7期43卷 616-621页

作者： Zhao, Da-Wei Su, Guang-Hui Tian, Wen-Xi Qiu, Sui-Zheng Sugiyama, K. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an 710049 China Faculty of Engineering Hokkaido University Kita 13 Jo Nishi 8 Chome Kita-Ku Sapporo 060-8628 Japan

An artificial neural network (ANN) for predicting Nusselt number was trained successfully based on the data of transition boiling experiment, which was conducted in confined space with downward facing surface at atmospheric pressure. The effects of wall superheat, Δtw, the ratio of the gap size to the diameter of heated surface, δ/D, Prandtl number and Rayleigh number on Nusselt number under transition boiling condition were analyzed based on the trained ANN. A correlation used to accurately predict the natural convection heat transfer under the present condition was obtained and it provides a reasonable agreement against the experimental data.

关键词： Facings

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Research on surface damage of solid material subjected to high speed liquid impact

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Binggong Xuebao/Acta Armamentarii 2009年第SUPPL. 2期30卷 139-144页

作者： Xie, Yong-Hui Wang, Yong Chen, Jian-Hui Zhang, Di State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an 710049 China

In order to study the surface damage of solid material subjected to the high speed liquid impact, both numerical and experimental methods were established. The smoothed particle hydrodynamics and finite element analysis were used to calculate the material damage. The conditions of PMMA and steel were analyzed to obtain the dynamic stress and strain distribution during impact. An experiment apparatus was build. The velocity of the impact jet was measured using a high speed camera and the apparatus. A digital microscope was used to measure the three dimensional profile of the sample before and after high speed liquid impact up to 600 m/s. The dimensions of damage area were recorded and analyzed statistically. Based on the statistical results, the performance of the materials resisting liquid corrosion was evaluated.

关键词： High speed cameras

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Optimal heat transfer criterion and inclination angle effects on non-boiling regime spray cooling

Optimal heat transfer criterion and inclination angle effect...

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IEEE Symposium on Semiconductor Thermal Measurement and Management (SEMI-THERM)

作者： Yong-xian Guo Zhi-fu Zhou Jian-yuan Jia Shao-rong Zhou School of Mechano-Electronic Engineering Xidian University Xi'an Shaanxi China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China Intel Asia-Pacific Research and Development Limited Shanghai China

Based on the maximum CHF (critical heat flux) criterion, an optimal heat transfer criterion, which is called H criterion, was proposed. Experimental apparatuses were conducted. Distilled water was used as the working fluid. Three different DANFOSS nozzles with cone angles being 54deg, 50deg and 54deg respectively were used to cool a 30times30 mm 2 square copper surface. Experimental results indicated that the volumetric fluxes were pro-portioned to P 0.5 , where P is the pressure drop across the nozzles. The optimal distance between the nozzles and the heated surface were derived. The results indicated that the optimal heat transfer appeared while the outside of the impellent thin spray film inscribed in the square heated surface. Based on the H criterion aforementioned, two DANFOSS nozzles of the three were used to study the temperature distribution of the heated surface experimentally while there were spray inclination angles. Distilled water was also used impacting on the 30times30 mm 2 square copper surface aforementioned and a circular heated copper surface with diameters being 30 mm respectively. The heat flux of the surface was kept in constant (about 26-35 W/cm 2 ). The inclination angles were 0deg, 10deg, 20deg, 30deg, 40deg and 50deg respectively. Experimental results indicated that the grads of the temperature of the surface increases first and then decreases with the increase of the inclination angle.

关键词： Heat transfer Spraying Temperature Electronics cooling Coolants Heat engines Copper Uncertainty Water heating Space exploration

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Clogging failure in microfilter for blood cell separation and its novel improvements

Clogging failure in microfilter for blood cell separation an...

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International Symposium on Physical & Failure Analysis of Integrated Circuits

作者： Tao Dong Zhaochu Yang Eirik Bentzen Egeland Frank Karlsen Henrik Jakobsen Norwegian Center of Expertise on Micro-and Nanotechnology I.M.S.T. /R. I Vestfold University College Norway State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

Clogging failure is common for microfilter utilizing the flat membrane structure. To reduce clogging failure in microfilters, the turbine blade-like micropillar is introduced in microfilter design. Two improved cross-flow microfilter designs employing the blade-like micropillar barrier are presented, one with varied cross-section channels, and the other with Archimedes' spiral channels. Analogy experimental-data based simulations show that the two aforementioned novel microfilters have good filtrating efficiency and fantastic anti-clogging characteristics. And the commercial value of the turbine blade-like barriers is affirmed by the industry Partners.

关键词： Microfiltration Cells (biology) Filters Biomembranes Filtration Turbines White blood cells Nanotechnology Educational institutions power engineering

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Online recognition of the multiphase flow regime

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Science China(Technological Sciences) 2008年第8期51卷 1186-1194页

作者： BAI BoFeng ZHANG ShaoJun ZHAO Liang ZHANG XiMin GUO LieJin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The key reasons that the present method cannot be used to solve the industrial multi- phase flow pattern recognition are clarified firstly. The prerequisite to realize the online recognition is proposed and recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of single sensor performance.

关键词： multiphase flow flow regime online recognition multi-sensor data fusion

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Effects of velocity ratio on turbulent mixing layer at high Reynolds number

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Journal of Physics: Conference Series 2009年第1期147卷

作者： Fude Guo Bin Chen Liejin Guo Ximin Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

In this paper the effect of velocity ratio on plane mixing layer was experimentally investigated by Particle Image Velocimetry (PIV). The velocity ratio between low and high speed side are 0.25 and 0.50, respectively. The Reynolds number based on the velocity difference of two streams and hydraulic diameter of the channel is 66000. The results indicate that the maximum mean Reynolds stress on the same cross section is decreasing with the velocity ratio increasing. The maximum dimensionless mean vorticity is decreasing according to an exponential law along the stream-wise direction and the decreasing speed of dimensionless mean maximum vorticity is increasing with the velocity ratio increasing. The dimensionless vorticity caused by plate wake is decreasing sharply in a very short distance along the down stream wise direction and the decreasing speed is faster when the velocity ratio is larger.

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PIV measurement of turbulent mixing layer flow with polymer additives

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Journal of Physics: Conference Series 2009年第1期147卷

作者： T Ning F Guo B Chen X Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Turbulent mixing layer flow with polymer additives was experimentally investigated by PIV in present paper. The velocity ratio between high and low speed is 4:1 and the Reynolds number for pure water case based on the velocity differences of two steams and hydraulic diameter of the channel ranges from 14667~73333. flow field and turbulent quantities of turbulent mixing layer with 200ppm polymer additives were measured and compared with pure water mixing layer flow. It is shown that the dynamic development of mixing layer is greatly influenced by polymer addictives. The smaller vortices are eliminated and the coherent structure is much clearer. Similar with pure water case, Reynolds stress and vorticity still concentrate in a coniform area of central part of mixing layer and the width will increase with the Reynolds number increasing. However, compared with pure water case, the coniform width of polymer additives case is larger, which means the polymer additives will lead to the diffusion of coherent structure. The peak value of vorticity in different cross section will decrease with the development of mixing layer. Compared with pure water case, the vorticity is larger at the beginning of the mixing layer but decreases faster in the case with polymer additives.

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Steady state investigation on neutronics of a molten salt reactor considering the flow effect of fuel salt

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Chinese Physics C 2008年第8期32卷 624-628页

作者：张大林秋穗正刘长亮苏光辉 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University School of Nuclear Science and Technology Xi'an Jiaotong University

The Molten Salt Reactor （MSR）, one of the ‘Generation Ⅳ＇ concepts, is a liquid-fuel reactor, which is different from the conventional reactors using solid fissile materials due to the flow effect of fuel salt. The study on its neutronics considering the fuel salt flow, which is the base of the thermal-hydraulic calculation and safety analysis, must be done. In this paper, the theoretical model on neutronics under steady condition for a single-liquid-fueled MSR is conducted and calculated by numerical method. The neutronics model consists of two group neutron diffusion equations for fast and thermal neutron fluxes, and balance equations for six-group delayed neutron precursors considering the flow effect of fuel salt. The spatial discretization of the above models is based on the finite volume method, and the discretization equations are computed by the source iteration method. The distributions of neutron fluxes and the distributions of the delayed neutron precursors in the core are obtained. The numerical calculated results show that, the fuel salt flow has little effect on the distribution of fast and thermal neutron fluxes and the effective multiplication factor; however, it affects the distribution of the delayed neutron precursors significantly, especially the long-lived one. In addition, it could be found that the delayed neutron precursors influence the neutronics slightly under the steady condition.

关键词： MSR steady state neutronics flow effect delayed neutron precursors

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Experimental study on steam plume and temperature distribution for sonic steam jet

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Journal of Physics: Conference Series 2009年第1期147卷

作者： Xinzhuang Wu Junjie Yan Wenjun Li Dongdong Pan Ying Li State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 P.R.China

The sonic steam jet in subcooled water was investigated experimentally over a wide range of steam mass flux and water temperature conditions. Four different steam plume shapes were observed in present test conditions, and the condensation form was mainly controlled by the steam mass flux and water temperature. Moreover, the unstable jet was observed on the condition of low steam mass flux and high water temperature. The transition criterion of unstable-stable jet was also given. The temperature fields in the steam plume and in the surrounding water were measured. Axial temperature distributions represented the four typical steam plumes, and the fluctuation of axial temperature confirmed the existence of expansion and compression waves. Additionally, the radial temperature distributions were independent of water temperature for small radial distance at nozzle exit, and further the axial location was apart from the nozzle exit, longer the radial distance affected by the momentum diffusion.

关键词：

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Determination of mass diffusion coefficients of oxygenated fuel additives in air using digital real-time holographic interferometry

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Journal of Physics: Conference Series 2009年第1期147卷

作者： Maogang He Ying Guo Qiu Zhong Ying Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 People's Republic of China

In this work, an experimental system based on digital real-time holographic interferometry for measuring the mass diffusion coefficients of fluid is introduced. The method of processing interference fringe hologram is also introduced thoroughly. By uncertainties analysis and experimental verification, the accuracy of this system is validated. The experimental uncertainties in temperature and mass diffusion coefficient are estimated to be no greater than ± 0.16 K and ± 0.2 %, respectively. On this basis, the mass diffusion coefficients of three fuel additives, diethyl 1,6-hexanedioate (diethyl adipate, DEA), dimethyl carbonate (DMC) and diethyl carbonate (DEC) in air were measured at T = (278.15 to 338.15) K under atmospheric pressure, and polynomial was fitted by the experimental data.

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