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Experimental and numerical study on flow separation control in rectangle diffuser

Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical engineering 2010年第5期30卷 92-99页

作者： Xie, Yong-Hui Fan, Tao Zhang, Di Ye, Dong-Ting Wang, Shun-Sen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi Province China

To investigate the mechanism of active control for flow separation in rectangle diffuser by vortex generator jets (VGJs) method, numerical analysis with large-eddy simulation and experimental measurement by particle image velocimetry (PIV) were carried out for the flow field. The numerical results show good agreement with experimental data. The two dimensional vortical structure was discussed in detail via the analysis of their velocity and vorticity distribution. Based on the three dimensional identification of vortex, several vortical structure, with emphasis on the dynamic process of its generation and development, was also discussed. The results show that the jet shear-layer vortices evolved from vortex loops to vortex rings as time go on. Horseshoe vortices wrap around the jet nozzle have the strong stability. The counter-rotating vortex pair has mean-flow definition although they may also have unsteady components. Moreover, to investigate the effect of VGJs on separation control, the surface pressure coefficient, the length of separation zone, the flow characteristics in diffuser and pressure power spectra were compared with and without VGJs. It revealed the longitudinal vortices generate at the downstream of jet increase cross-stream mixing of streamwise momentum and then suppress or delay the separation in diffuser. © 2010 *** ***.

关键词： Large eddy simulation

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A MEMS density sensor based on mircro-rectangular cantilever

A MEMS density sensor based on mircro-rectangular cantilever

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International Conference on Mechanic Automation and Control engineering (MACE)

作者： Libo Zhao Zhuangde Jiang Enze Huang Zhigang Liu State Key Laboratory of Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an China State Key Laboratory of Multiple Flow in Power Engineering Xi'an Jiaotong University Xi'an China

A rectangle cantilever-type micro density sensor was researched based on MEMS (Micro Electro-mechanical System) technology. A Ti-Pt-Au coil and a Wheatstone full bridge were made on the top of the rectangle cantilever-type sensitive chip. The sensitive chip was placed in uniform strong magnetic field. The resonant frequency of the sensitive chip was changed with the change of the AC current's frequency. The resonant frequency of rectangle cantilever could be measured through the Wheatstone full bridge circuit and lock-in amplifier, and then the fluid density associated with the resonant frequency of the sensitive chip could be calculated. The static analysis, modal analysis, a first-order and third-order harmonic response analysis of the rectangle cantilever were performed with ANSYS software. The best locations of the four force-sensitive resistor of Wheatstone bridge were studied.

关键词： Micromechanical devices Bridge circuits Resonant frequency Magnetic sensors Magnetic field measurement Harmonic analysis Performance analysis Sensor systems Coils Density measurement

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Research on the Preparation of (CuAg)xIn2xZn2(1−2x)S2 Solid Solution Photocatalysts

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AIP Conference Proceedings 2010年第1期1207卷 1066-1069页

作者： K. Zhang D. W. Jing C. J. Xing L. J. Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University China

ZnS‐CuInS2‐AgInS2 solid solution photocatalysts were successfully prepared by co‐precipitation method with heat treatment under different atmosphere ( N2 and H2S). XRD, XRF, UV‐vis, and SEM were used to characterize the prepared photocatalysts, indicated that the composition of result photocatalysts were different from each other and also the rate of charge, though they possessed a wurtzite‐type phase structure. The photocatalysts all showed photocatalytic activities for H2 evolution from aqueous solutions containing SO32− and S2− as sacrificial reagents under visible light irradiation with Ru loading, but sample treated under H2S atmosphere performed better, the possible reason was proposed.

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Emission Characteristics and Axial Flame Temperature Distribution of a Circumferential Reverse flow Combustor

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Journal of Energy and power engineering 2010年第7期4卷 9-14页

作者： C. Dong Q.L. Zhou X.G. Zhang P. Sun T.M. Xu S.E. Hui Q.X. Zhao State Key Laboratory of Multiphase Flow in Power Engineering Xi ＇an Jiaotong University Xi ＇an 710049 China

In partially premixed combustion of gas turbine, the combustion temperature should be lowed in order to reduce NOx. One solution is lean premixed combustion. However, the problem is that large excess air ratio may make the combustion unstable. A novel combustor with circumferential reverse flow of fuel gas is proposed for settling this problem. A 10 kw furnace is established to test performance of this combustor. Three factors such as primary air ratio, position of secondary air, total excess air ratio are studied. The emission characteristics and axial flame temperature distribution are studied. Basing on experimental results, the axial flame temperature and NOr emission increase with primary air ratio and axial length of second stream, and decrease with total excess air ratio. When the total excess air ratio is larger than 1.05, the combustor presents a lower temperature field and much lower NOx emission （less than 10 ppm）.

关键词： Partially premixed combustor secondary air distributor NOx emission axial flame temperature experimentalinvestigation.

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Experimental Study of Falling Film on the Outside of Horizontal Tube

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AIP Conference Proceedings 2010年第1期1207卷 238-243页

作者： L. B. Yan H. X. Li B. Guo Y. Q. Zhang Z. Zhang Y. F. Zhang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Evaporating falling film on horizontal tubes has been widely used in desalinization, refrigeration, chemical process industries, and so on. In this paper, the flow characteristics of falling film outside horizontal tubes in horizontal air flows was studied theoretically and experimentally. Two low patterns of the falling film, i.e., droplet flow pattern and columnar flow pattern, were considered. Effects of the velocity of airflow, the flux of falling film flow, the external diameter of tube and the surface property of tube on the falling film flowing characters were investigated. Experimental study indicated that, in a definite flow scale, as the flow increased, the diameters of falling droplets and falling columns of the liquid enlarged, and the liquid film became thick and the area covered by the liquid film increased. As the air velocity increased, the offset of the droplet and the column to the top of the tube enlarged, and the rate of increase come down until it complete depart from the the top of the horizontal tube. Besides, a theoretical model was established about the offset of the droplet and liquid column from the top of the tube under the force of the horizontal air flows, and the model was validated by a comparison between the numerical predictions and experimental data.A further analysis about the excursion law of falling film flow outside horizontal tube was also made at the last paprt of the paper.

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Slagging characteristics on the superheaters of a 12 MW biomass-fired boiler

Slagging characteristics on the superheaters of a 12 MW biom...

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作者： Niu, Yanqing Tan, Hongzhang Ma, Lin Pourkashanian, Mohamed Liu, Zhengning Liu, Yang Wang, Xuebin Liu, Haiyu Xu, Tongmo State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xian Jiaotong University Xian 710049 China School of Process Environmental and Materials Engineering University of Leeds Leeds LS2 9JT United Kingdom

In an attempt to understand the problem of severe slagging in biomass-fired boilers, slags formed on the fourth-, second-, and first-stage superheaters in a 12 MW biomass-fired grate furnace have been collected, sampled, and analyzed using X-ray fluorescence (XRF) and X-ray diffraction (XRD) techniques. The slag collected on each superheater has a unique morphology and structure. The slag on the fourth-stage superheater is loose and porous, while on the secondary and the primary superheaters, the slag shows a clear layered structure of different colors and levels of hardness. Aluminosilicate is the major component in the slag on the fourth-stage superheater, which is formed by Si, Al, and alkali species. On both the secondary and primary superheaters, the sticky sylvine, potassium calcium sulfate, and aphthitalite in the bottom layer trap coarse, large particles, resulting in further slagging. In the alternating layers, the particles containing high concentrations of K, Na, and Cl form the initial deposit layer, the yellow layer in the secondary superheater. Then, it traps the coarse, large particles containing high Si, Al, Ca, Mg, and Fe to form the brown layer. Similarly, the particles in the pale-yellow layer of the primary superheater containing high concentrations of K, Na, and Cl form the initial deposit layer, and then, it traps the coarse, large particles containing high Si, Al, Ca, Mg, and Fe to form the black layer. Accompanied by the periodic blowing, the alternating layer is formed and the slag gradually becomes thicker. © 2010 American Chemical Society.

关键词： Iron

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Experimental Research on the Performance of Exhaust Steam Reclaim Device With a Swirling flow Vane

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AIP Conference Proceedings 2010年第1期1207卷 374-379页

作者： X. L. Li J. J. Yan P. F. Zhang J. J. Yang J. P. Liu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University P.R. China

This paper experimentally studied the performance of exhaust steam reclaim device with a swirling flow vane at different inlet water pressures, temperatures, different inlet steam pressures and different distances between the throat and spout. The results indicated that the injection coefficient decreased as the inlet water pressure and temperature increased, respectively. There is a best distance between the throat and spout which makes the injection coefficient reached to its maximal value at the same experimental pressure and temperature, and the value equals to 130 mm in our experimental system. The resistance coefficient has a minimum value which makes the device have the highest outlet water pressure. Compared with the device without a swirling flow vane, it improves the heating performance for higher injection coefficient and exergy efficiency.

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THE VELOCITY FIELD OF MULTIPHASE flow AND EFFICIENCY OF BIOLOGICAL AERATION FILTER

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Journal of Hydrodynamics 2010年第2期22卷 260-264页

作者： CHENG Wen HU Bao-wei YANG Chun-di CHENG Wen-juan Environment Research Institute Xian University of Technology Xi＇an 710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi＇ an Jiaotong University Xi＇an 710049 China Key Laboratory of Northwest Water Resources and Environmental Ecology of Education Ministry Xi＇anUniversity of Technology Xi＇an 710048 China Yuanpei College Shaoxing University Shaoxing 312000 China Environment Research Institute Xi＇an University of Technology Xi＇an 710048 China

Aeration is an important factor affecting the biological aeration *** a set of experiment device specially designed for the purpose,and the particle image velocimetry technique,the velocity field of the gas-liquid two-phase flow is studied under different *** various simulated aeration states were actually applied to the experimental device of sewage treatment,and the results of the numerical simulation were *** final experimental results indicate that the most efficient state occurs when the ratio of water in aeration tank h / w =1,the diameter of capillary tubes d=0.6mm and the velocity of bubbles v=0.3m/s.

关键词： ratio of water diameter of capillary tube bubbles velocity sewage disposal efficiency

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A MEMS density sensor based on mircro-rectangular cantilever

A MEMS density sensor based on mircro-rectangular cantilever

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2010 International Conference on Mechanic Automation and Control engineering, MACE2010

作者： Zhao, Libo Huang, Enze Jiang, Zhuangde Liu, Zhigang State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an China State Key Lab. of Multiple Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9781424477388

关键词： Natural frequencies

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A MEMS resonator-type viscosity sensor based on triangular cantilever

A MEMS resonator-type viscosity sensor based on triangular c...

引用

2010 International Conference on Mechanic Automation and Control engineering, MACE2010

作者： Zhao, Libo Zhang, Guiming Jiang, Zhuangde Liu, Zhigang State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an China State Key Lab. of Multiple Flow in Power Engineering Xi'an Jiaotong University Xi'an China

ISBN: (纸本)9781424477388

A MEMS (Micro Electro-mechanical System) resonator-type viscosity sensor with range from 0 to 1 mPa·s was presented with good frequency response and high sensitivity. Its sensitive chip with a triangular cantilever structure was investigated. This paper studied the operating principle of the MEMS resonator-type viscosity sensor. The natural frequency of the sensitive chip was deduced with its structure size in theory, which was validated with ANSYS finite element software. The modal analysis and harmonic response analysis for the sensitive chip with triangular cantilever structure were performed to determine the resonant mode of the MEMS viscosity sensor. Finally, the layout and fabrication processes of the sensitive chip of the MEMS resonator-type viscosity sensor were designed and studied. The sensitive chip with small size, high sensitivity and high temperature resistance was fabricated with MEMS technology on SOI (Silicon on Insulator) monocrystalline in order to achieve real-time on-line measurement of fluid viscosity. ©2010 IEEE.

关键词： Natural frequencies

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