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PIV measurement of turbulent mixing layer flow with polymer additives

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.

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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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Measurement of falling film thickness around a horizontal tube using laser-induced fluorescence technique

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

作者： Xiaofei Wang Maogang He Hualiang Fan Ying Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 People's Republic of China

An optical method for the non-intrusive measurement of falling film thickness on the perimeter of the horizontal tube is described. This non-intrusive measurement method is based on the visualization of the falling film flowing around the horizontal tube and uses the laser induced fluorescence and image processing techniques. The falling film thickness around a Turbo-CII horizontal tube and a plain horizontal tube was measured when water flushed the tube vertically with a stable velocity. The results for the Turbo-CII tube are compared with those for the plain tube, and show that the film thickness around the Turbo-CII tube varies with the same trend as that around the plain tube, and the minimal values of the film thickness tend to locate at different angular position of 95°-120° under different conditions. The film thickness around the enhanced tube changes within a smaller range with time than that around the plain tube. The corresponding effects on flow uniformity have also been discussed.

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First law-based thermodynamic analysis on Kalina cycle

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中国高等学校学术文摘·能源与动力工程 2008年第2期2卷 145-151页

作者： Ying ZHANG Maogang HE Zhen JIA Xun LIU State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

Based on the first law of thermodynamics,and adopting the Peng-Robinson equation (P-R equation) as the basic equation for the properties of ammonia-water mixtures,a thermodynamic analysis on a single-stage distillation Kalina cycle is presented.A program to calculate the thermodynamic properties of ammoniawater mixtures,and that for calculating the performance of Kalina cycles,were developed,with which the heatwork conversion particulars of Kalina cycles were theoretically *** influences on the cycle performance of key parameters,such as the pressure and temperature at the inlet of the turbine,the back pressure of the turbine,the concentration of the working solution,the concentration of the basic solution and the cycle multiplication ratio,were analyzed.

关键词： engineering thermophysics Kalina cycle ammonia-water mixtures P-R equation thermodynamic property

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Effect of ignition timing and hydrogen fraction on combustion and emission characteristics of natural gas direct-injection engine

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中国高等学校学术文摘·能源与动力工程 2008年第2期2卷 194-201页

作者： Jinhua WANG Zuohua HUANG Bing LIU Ke ZENG Jinrong YU Deming JIANG State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

An experimental study on the combustion and emission characteristics of a direct-injection spark-ignited engine fueled with natural gas/hydrogen blends under various ignition timings was *** results show that ignition timing has a significant influence on engine performance,combustion and *** interval between the end of fuel injection and ignition timing is a very important parameter for direct-injection natural gas *** turbulent flow in the combustion chamber generated by the fuel jet remains high and relative strong mixture stratification is introduced when decreasing the angle interval between the end of fuel injection and ignition timing giving fast burning rates and high thermal *** maximum cylinder gas pressure,maximum mean gas temperature,maximum rate of pressure rise and maximum heat release rate increase with the advancing of ignition ***,these parameters do not vary much with hydrogen addition under specific ignition timing indicating that a small hydrogen fraction addition of less than 20% in the present experiment has little influence on combustion parameters under specific ignition *** exhaust HC emission decreases while the exhaust CO2 concentration increases with the advancing of ignition *** the lean combustion condition,the exhaust CO does not vary much with ignition *** the same ignition timing,the exhaust HC decreases with hydrogen addition while the exhaust CO and CO2 do not vary much with hydrogen *** exhaust NOx increases with the advancing of' ignition timing and the behavior tends to be more obvious at large ignition advance *** brake mean effective pressure and the effective thermal efficiency of natural gas/hydrogen mixture combustion increase compared with those of natural gas combustion when the hydrogen fraction is over 10%.

关键词： natural gas hydrogen ignition timing combustion emissions direct-injection

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Hydrogen production by catalytic gasification of cellulose in supercritical water

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Frontiers of Chemical Science and engineering 2008年第2期2卷 176-180页

作者： Yu GUAN Aixia PEI Liejin GUO State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

Cellulose,one of the important components of biomass,was gasified in supercritical water to produce hydrogen-rich gas in an autoclave which was operated batch-wise under high-pressure.K_(2)CO_(3) and Ca(OH)2 were selected as the catalysts(or promoters).The temperature was kept between 450uC and 500uC while pressure was maintained at 24–26 *** reaction time was 20 *** results showed that the two catalysts had good catalytic effect and optimum amounts were observed for each *** 0.2 g K_(2)CO_(3) was added,the hydrogen yield could reach 9.456 mol?kg21 which was two times of the H2 amount produced without *** 1.6 g Ca(OH)2 was added,the H2 yield was 8.265 mol?kg21 which is lower than that obtained using K_(2)CO_(3) as catalyst but is still 1.7 times that achieved without *** with the results obtained using K_(2)CO_(3) or Ca(OH)2 alone,the use of a combination of K_(2)CO_(3) and Ca(OH)2 could increase the H2 yield by up to 2.5 times that without catalyst and 25%and 45%more than that obtained using K_(2)CO_(3) and Ca(OH)2 alone,*** was found that methane was the dominant product at relatively low *** the temperature was increased,the methane reacts with water and is converted to hydrogen and carbon dioxide.

关键词： biomass hydrogen production supercritical water gasification hydrogen

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Numerical investigation and analysis of heat transfer enhancement in channel by longitudinal vortex based on field synergy principle

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中国高等学校学术文摘·能源与动力工程 2008年第1期2卷 71-78页

作者： Wenquan TAO Junmei WU State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Environment and Chemical Engineering Xi'an Polytechnic University Xi'an 710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

3-D numerical simulations were presented for laminar flow and heat transfer characteristics in a rectangular channel with vortex generators. The effects of Reynolds number (from 800 to 3 000), the attack angle of vortex generator (from 15° to 90°) and the shape of vortex generator were examined. The numerical results were analyzed based on the field synergy principle. It is found that the inherent mechanism of the heat transfer enhancement by longitudinal vortex can be explained by the field synergy principle, that is, the second flow generated by vortex generators results in the reduction of the intersection angle between the velocity and fluid temperature gradient. The longitudinal vortex improves the field synergy of the large downstream region of longitudinal vortex generator (LVG) and the region near (LVG); however, transverse vortex only improves the syn-ergy of the region near vortex generator. Thus, longitudinal vortex can enhance the integral heat transfer of the flow field, while transverse vortex can only enhance the local heat transfer. The synergy angle decreases with the increase of Reynolds number for the channel with LVG to differ from the result obtained from the plain channel, and the triangle winglet performs better than the rectanglar one under the same surface area condition.

关键词： longitudinal vortex heat transfer enhancement field synergy principle

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Experimental investigation of particle velocity distributions in windblown sand movement

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Science China(Physics,Mechanics & Astronomy) 2008年第8期51卷 986-1000页

作者： KANG LiQiang GUO LieJin LIU DaYou State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Division of Engineering Sciences Institute of MechanicsChinese Academy of SciencesBeijing 100190China

With the PDPA(Phase Doppler Particle Analyzer) measurement technology,the probability distributions of particle impact and lift-off velocities on bed surface and the particle velocity distributions at different heights are detected in a wind tunnel. The results show that the probability distribution of impact and lift-off velocities of sand grains can be expressed by a log-normal function,and that of impact and lift-off angles complies with an exponential function. The mean impact angle is between 28° and 39°,and the mean lift-off angle ranges from 30° to 44°. The mean lift-off velocity is 0.81-0.9 times the mean impact velocity. The proportion of backward-impacting particles is 0.05-0.11,and that of backward-entrained particles ranges from 0.04 to 0.13. The probability distribution of particle horizontal velocity at 4 mm height is positive skew,the horizontal velocity of particles at 20 mm height varies widely,and the variation of the particle horizontal velocity at 80 mm height is less than that at 20 mm height. The probability distribution of particle vertical velocity at different heights can be described as a normal function.

关键词： windblown sand movement probability distribution particle velocity

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