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Experimental study of composition and influence factors on fouling of stainless steel and copper in seawater

ANNALS OF NUCLEAR ENERGY 2016年 94卷 767-772页

作者： Yang, Dazhang Liu, Jianhua E, Xiaoxue Jiang, Linlin Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Peoples R China Key Lab Multiphase Flow & Heat Transfer Shanghai Shanghai Peoples R China

Metals and alloys are easily fouled in marine environment. It is a big problem for heat exchangers using cooling seawater in power plants or ships. In the paper, a seawater-fouling dynamic test device was built to investigate the composition and influence factors on fouling of stainless steel and copper in the cooling seawater system. Moreover, the static trials were performed to study the fouling and corrosion of stainless steel and copper in marine environment. The experimental results show that the seawater fouling of stainless steel is crystallization fouling, and the main elements of fouling are magnesium and aluminum. In addition, the results show that the seawater fouling of copper is corrosion fouling. In the dynamic experiments, the effects of heat flux and Reynolds number on stainless steel fouling were studied. The results show that higher heat flux and higher Reynolds number of seawater lead to the accumulation of seawater fouling. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Fouling Seawater Composition Influence factor Stainless steel Copper

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A multi-objective optimization for HAWT blades design by considering structural strength

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2016年第8期30卷 3693-3703页

作者： Yang, Yang Li, Chun Zhang, Wanfu Yang, Jun Ye, Zhou Miao, Weipao Ye, Kehua Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The challenge of wind turbine blade design is to balance the conflict between high capacity and heavy system loads introduced by the large scale rotor. To solve this problem, we present a multi-objective optimization method to maximize the Annual energy production (AEP) and minimize the blade mass. The well-known Blade element momentum (BEM) theory is employed to predict the aerodynamic performance and AEP of the blade. The blade is simplified as a thin Bernoulli beam. The cross section is modelled as a combination of composite layer, shear webs and spar caps typically. The strain of every cross section has been considered as a constraint to minimize the spar cap thickness for minimizing the blade mass. An improved genetic algorithm (NSGA-II) is applied to obtain the Pareto front set. Several solutions of the Pareto set are selected to compare with the reference blade (NREL 5MW blade). Performance of the rotors on design condition is simulated by STAR-CCM+ to verify the results of BEM theory. Optimal results show that the present blade, which is fully superior to the reference blade, can be selected from the Pareto set. The optimization design method can provide a superior blade with an increase by 2.48% of AEP and a reduction by 5.52% of the blade mass. It indicates the present optimization method is effective. Results of numerical simulations show that the spanwise flow would be increased obviously in tip region of the reference blade. The reason is that chord length variation in blade tip affects the flow and causes minor stall. The abrupt change of chord distribution in blade tip should be avoided to reduce the spanwise flow in initial blade design.

关键词： Annual energy production (AEP) Genetic algorithm Multi-objective optimization Pareto solutions Wind turbine blade

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Characterization of Soot Based on Variable Laser-induced Spectroscopy

Characterization of Soot Based on Variable Laser-induced Spe...

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Progress in Electromagnetic Research Symposium (PIERS)

作者： Zhang, Yanfeng Chen, Jun Yang, Huinan Su, Mingxu Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Sch Energy & Power Engn Shanghai Peoples R China

ISBN: (纸本)9781509060931

Laser-induced incandescence (LII) is a non-intrusive method of measuring time-resolved soot particle volume fraction and primary particle sizes. We also can know the component by increasing the laser energy to the regime of laser-induced breakdown spectroscopy (LIBS). More model analysis and experiments should be studied to understand the LII/LIBS.

关键词： Laser induced breakdown spectroscopy

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Numerical investigation on energy extraction of flapping hydrofoils with different series foil shapes

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ENERGY 2016年 112卷 1153-1168页

作者： Wang, Ying Sun, Xiaojing Huang, Diangui Zheng, Zhongquan Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Univ Kansas Dept Aerosp Engn Lawrence KS 66045 USA

As a new mode of energy extraction, flapping foils show broad application prospects. How to improve the energy extraction efficiency (eta) of wind or hydro energy with flapping foils has become a focused issue for scientists in this field. This paper numerically investigated the energy extraction of flapping hydrofoil with different NACA 4 and NACA 6 series foil shapes. Firstly, compared with experimental results, the simulation results were validated. Secondly, by adopting different series of foil shapes, simulation was conducted for energy extraction of flapping foils which were moving harmonically in current: (sic) symmetric foils with different maximum thicknesses;(sic) symmetric foils with different maximum thickness positions;(sic) non-symmetric foils with same maximum thickness, maximum thickness position and camber, but different maximum camber positions;(sic) non-symmetric foils with same maximum thickness, maximum thickness position and camber position, but different maximum cambers. It is found that for symmetric foils with different maximum thicknesses, eta basically increases first and then decreases with the increase of maximum thickness;for symmetric foils with different maximum thickness positions, eta first increases and then decreases when maximum thickness position moves from the leading edge to the trailing edge;for non-symmetric foils with same thickness, eta shows lower value with larger camber;compared with maximum camber position, the maximum thickness shows larger influence on eta. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Flapping hydrofoils Different foil shapes Current energy Energy extraction efficiency UCFD

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Origin of Granular Capillarity Revealed by Particle-Based Simulations

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Physical Review Letters 2017年第21期118卷 218001-218001页

作者： Fengxian Fan Eric J. R. Parteli Thorsten Pöschel Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Jun Gong Road 516 200093 Shanghai China Institute for Multiscale Simulation Friedrich-Alexander-Universität Erlangen-Nürnberg Nägelsbachstraße 49b 91052 Erlangen Germany Department of Geosciences University of Cologne Pohligstraße 3 50969 Cologne Germany

When a thin tube is dipped into water, the water will ascend to a certain height, against the action of gravity. While this effect, termed capillarity, is well known, recent experiments have shown that agitated granular matter reveals a similar behavior. Namely, when a vertical tube is inserted into a container filled with granular material and is then set into vertical vibration, the particles rise up along the tube. In the present Letter, we investigate the effect of granular capillarity by means of numerical simulations and show that the effect is caused by convection of the granular material in the container. Moreover, we identify two regimes of behavior for the capillary height Hc∞ depending on the tube-to-particle-diameter ratio, D/d. For large D/d, a scaling of Hc∞ with the inverse of the tube diameter, which is reminiscent of liquids, is observed. However, when D/d decreases down to values smaller than a few particle sizes, a uniquely granular behavior is observed where Hc∞ increases linearly with the tube diameter.

关键词： Classical mechanics Complex systems Wetting Dry granular materials

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Experimental study on gasification performance of bamboo and PE from municipal solid waste in a bench-scale fixed bed reactor

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ENERGY CONVERSION AND MANAGEMENT 2016年第Jun.期117卷 393-399页

作者： Zheng, Xiaoyuan Chen, Chong Ying, Zhi Wang, Bo Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer 516 Jungong Rd Shanghai 200093 Peoples R China Shanghai Urban Construct Design & Res Inst 3447 Dongfang Rd Shanghai 200125 Peoples R China

Gasification performance of key components including polyethylene (PE) and bamboo of municipal solid waste (MSW) was examined in a bench-scale fixed bed. Effects of equivalence ratio, gasification temperature, steam/feedstock ratio, and calcium oxide (CaO) presence on syngas composition and lower heating value (LHV) were investigated. As equivalence ratio increased, both combustible gas components and LHV of syngas from bamboo and PE gasification decreased while the yield of CO2 increased generally. Higher gasification temperature favored improving H-2 and CO production and lowering the yield of CO2 from PE gasification while an optimal temperature of 700 degrees C existed for the best syngas quality and the highest LHV of syngas from bamboo gasification. Different variations of CO2 between bamboo and PE were observed as steam/feedstock ratio increased. CaO was more effective to increase the yields of H-2, CO, and CH4 and lower the yield of CO2 from bamboo and PE gasification under both air and steam atmosphere, excluding the syngas composition of PE steam gasification. The work described here favors us understand the real MSW gasification process and thus facilitates the industrial application of gasification technology. (c) 2016 Elsevier Ltd. All rights reserved.

关键词： MSW Gasification Fixed bed reactor Hydrogen Calcium oxide

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Three-dimensional positioning method for moving particles based on defocused imaging using single-lens dual-camera system

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Chinese Optics Letters 2016年第3期14卷 42-46页

作者：周骛金娜贾敏华杨荟楠蔡小舒 Institute of Particle and Two-Phase Flow Measurement/Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education Southeast University

A method to three-dimensional position moving particles with one lens and two cameras is proposed. Two par- ticle images with different degrees of defocusing are adopted to solve the ambiguous problem of particle positions. A single-lens dual-camera system is developed to simultaneously capture these two images for the moving par- ticles. The measurement principles and theoretical analysis are introduced first, and then simulated investiga- tions and experimental research are discussed. The measurement errors in the simulations and experiments are less than 1% and 4%, respectively, in 20 times the depth of field of the system, which validates the feasibility of this method.

关键词： Optics Physics

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Influence of tilting rotor on characteristics of fluid-induced vibration for labyrinth seals

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JOURNAL OF VIBROengineering 2016年第8期18卷 5416-5431页

作者： Zhang, Wanfu Zhang, Yao Yang, Jiangang Li, Chun Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Southeast Univ Natl Engn Res Ctr Turbo Generator Vibrat Nanjing 210096 Jiangsu Peoples R China

Labyrinth seal is a key component for the safe and reliable operation of a turbine unit. This paper sets up a three-dimensional numerical model of a labyrinth seal with a tilting rotor based on a compressor eye seal which was studied by Computational Fluid Dynamics method and a test labyrinth seal. The influence of the tilting rotor on the static and dynamic characteristics of labyrinth seals was investigated. Numerical results demonstrated a good agreement with the published article. Both the radial and tangential fluid-induced forces show an obvious increase when the rotor is in tilting conditions. From an efficiency viewpoint, a bigger tilt angle of the rotor is desirable. And eccentricity existence is not beneficial to the seal performance. The results based on the test seal show the whirl frequency ratio increases with the increasing eccentricity ratio. In case of tilting conditions (delta = 0.05 mm, theta = 0.8 deg), the whirl frequency ratio decreases with the increasing rotational speed. The higher rotational speed will be beneficial to the stability improvement when the rotor is in tilting conditions. The whirl frequency ratio also shows a decrease with the increasing inlet pressure. The higher inlet pressure tends to improve the stability when the rotor is in tilting conditions. All the stiffness coefficients and damping coefficients increase as the tilt angle increases. The whirl frequency ratio also shows an increase with the increasing tilt angle. The tilting rotor tends to reduce the stability when the rotor is in eccentric conditions.

关键词： labyrinth seal fluid-induced vibration computational fluid dynamics (CFD) whirl frequency ratio

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Numerical investigation on flow-induced structural vibration and noise in centrifugal pump

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JOURNAL OF VIBROengineering 2016年第4期18卷 2448-2459页

作者： Chen, Eryun Zhao, Gaiping Li, Guoping Nan, Guofang Yang, Ailing Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Sch Med Instruments & Food Engn Shanghai 200093 Peoples R China Shanghai Marine Equipment Res Inst Shanghai 200031 Peoples R China

A full scale structural vibration and noise induced by flow was simulated by a hybrid numerical method. An interior flow field was solved by large eddy simulation firstly. The sliding mesh technique was applied to take into account the impeller-volute interaction. A sensitivity analysis on effects of near-wall grid size and sampling time on amplitude of pressure pulsations was performed to impose appropriate vibration exciting source. Computed modal of pump components was validated by experimental results, before the volute vibration and sound field were simulated using a coupled vibro-acoustic model. The numerical results indicated that the amplitude of pressure fluctuation, especially on those points located at near the volute tongue, strongly depended on near-wall grid size. The dominated frequency of the vibration velocity of volute was also blade-passing frequency (BPF), which was in according with frequency spectral characteristics of unsteady pressure fluctuation. Directivity distribution of radiation acoustic field excited by volute vibration was typical dipoles. This study shows that it is feasible to use the hybrid numerical method to evaluate the flow-induced vibration and noise generated in centrifugal pump.

关键词： pressure pulsation vibration and noise coupled vibro-acoustic model centrifugal pump

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Numerical investigation on vibration and noise induced by unsteady flow in an axial-flow pump

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JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY 2016年第12期30卷 5397-5404页

作者： Chen, Eryun Ma, Zuiling Zhao, Gaiping Li, Guoping Yang, Ailing Nan, Guofang Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Sch Med Instruments & Food Engn Shanghai 200093 Peoples R China Shanghai Marine Equipment Res Inst Shanghai 200031 Peoples R China

Full-scale structural vibration and noise induced by flow in an axial-flow pump was simulated by a hybrid numerical method. An unsteady flow field was solved by a large eddy simulation-based computational fluid dynamics commercial code, Fluent. An experimental validation on pressure fluctuations was performed to impose an appropriate vibration exciting source. The consistency between the computed results and experimental tests were interesting. The modes of the axial-flow pump were computed by the finite element method. After that, the pump vibration and sound field were solved using a coupled vibro-acoustic model. The numerical results indicated that the the blade-passing frequency was the dominant frequency of the vibration acceleration of the pump. This result was consistent with frequency spectral characteristics of unsteady pressure fluctuation. Finally, comparisons of the vibration acceleration between the computed results and the experimental test were conducted. These comparisons validated the computed results. This study shows that using the hybrid numerical method to evaluate the flow-induced vibration and noise generated in an axial-flow pump is feasible.

关键词： Vibration and noise Pressure fluctuations Numerical simulation Experiment validation Axial-flow pump

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