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Accuracy analysis of moving particle semi-implicit method

Kung Cheng Je Wu Li Hsueh Pao/Journal of Engineering Thermophysics 2011年第SUPPL. 1期32卷 146-149页

作者： Duan, Guang-Tao Chen, Bin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The viscous and pressure gradient terms, which can be solved by Green Function method theoretically, are calculated separately in MPS method. Through the analysis of kernel function, an accuracy condition of viscous term is proposed and the reasonable match between spatial and time step will increase the accuracy and stability of MPS method. Poiseuille flow is simulated and the accuracy condition is validated. In the analysis of the source term of Pressure Poisson equation, the particle number density (PND), which is very sensitive to the relative configuration of particles, yields the deviation of velocity profile from the theoretical solution. It is the fluctuation in PND that causes the spurious fluctuation of pressure.

关键词： Poisson equation

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Stress analysis of heat exchange tube with inner and outer fins under convection heat transfer conditions

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Huagong Xuebao/CIESC Journal 2011年第SUPPL. 1期62卷 86-91页

作者： Ji, Yanpeng Ma, Ting Zeng, Min Wang, Qiuwang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China

The heat exchange tube with inner and outer fins has been widely applied in industry in order to enhance the performance of heat exchangers. When it is used in high temperature environment, the security must be considered. A three-dimension model was established to simulate the thermal stress by software ANSYS. The results indicated that the main factor, which had effect on the stress and deformation, was temperature and the maximum stress occurred at the joint location between inner fins and tubes. The inner pressure distribution of tube could enhance the effect of stress. On the contrary, the outer could weaken the effect. © All Rights Reserved.

关键词： Finite element method

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Experimental study of natural convection in horizontally-positioned open-celled metal foams

Experimental study of natural convection in horizontally-pos...

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International Conference on Materials for Renewable Energy and Environment

作者： Z. G. XU Z. G. QU C. Y. ZHAO State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi'an Jiaotong University

ISBN: (纸本)9781612847498

Experimental study of air natural convection in horizontally-positioned copper metallic foams with open cells was conducted. Temperature distributions on the heating surface were tested under different heating power for foam samples having different porosities and pore densities. The effects of porosity and pore density on the total thermal resistance of the foam sample were quantified. It is found that the porous surface can enhance the natural convection and reduce the thermal resistance by about 20% in comparison with a smooth surface. The surface area density and mass flow rate in natural convection are affected by porosity and pore density simultaneously. When the porosity is relative small (ε = 90%), there exits a critical value of the Gr number (turning point) for two pore densities (10ppi and 40ppi). When the Gr number is less than this critical value, the foam with a higher pore density has the lower total thermal resistance, whereas when the Gr number exceeds the turning point value, the opposite holds. If the porosity is increased to ε = 95%, the foam with a higher pore density has the lower thermal resistance in the whole experimental range. When the porosity and pore density is the same, the foam with smaller size has the higher thermal resistance in the whole experimental range. If the size is relatively small (100×100×50mm), for the two pore densities studied (20ppi and 80ppi), there exits a critical value of the Gr number (turning point). The foam with a lower porosity (ε = 90%) has the lower thermal resistance and the decrease is more obvious for the case of 80ppi. If the size is relatively big(100×100×80mm), there exists a critical value of the Gr number (turning point) only for the case of 10ppi. When the Gr number is less than this critical value, the foam with a higher porosity (ε = 95%) has the higher total thermal resistance, the opposite holds. While for the other two pore densities (20ppi and 40ppi), there is no turning point. The foam with

关键词： Metal foam Natural convection Porosity Pore density Thermal resistance

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Single electron loss in the collisions of C^(3+) and atomic hydrogen

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Chinese Physics B 2010年第9期19卷 344-348页

作者：刘会平欧阳晓平胡华四苏光辉 State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi'anjiaotong University

This paper studies the projectile electron loss cross sections of C^3＋ colliding with atomic hydrogen in the frame work of extended over-barrier model at intermediate velocities （25 keV/u-600 keV/u）. The electron loss is calculated in terms of the interaction between the screened target nucleus and the active projectile electron and of the interaction between projectile electron and target electron. Compared with the convergent close-coupling calculations, screening and anti-screening calculations, this model satisfactorily reproduces the experimentally obtained energy dependence of the electron-impact ionisation cross sections and the single electron loss cross sections over the energy range investigated here.

关键词： single electron loss over-barrier model

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Measurement of laminar burning velocities of iso-butanol-air mixtures

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Chinese Science Bulletin 2010年第19期55卷 2046-2056页

作者： FENG PengFei GU XiaoLei HUANG ZuoHua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The laminar burning velocity of iso-butanol-air mixtures was measured under different initial pressures,initial temperatures and equivalence ratios using high-speed schlieren photography and outwardly propagation flame in a constant volume combustion *** on the analysis of stretched flame propagation speed and stretch rate,the laminar burning velocities and Markstein lengths of iso-butanol-air flames are *** accordance,with photos of flame,an analysis of flame stability and the influencing factors is carried *** results show that the laminar burning velocity is decreased with the increase of initial pressure and is increased with the increase of initial *** maximum value of laminar burning velocity is presented at the equivalence ratio of *** Markstein length is decreased with the increase of equivalence *** specified equivalence ratio,the Markstein length is decreased with the increase of initial temperature and initial ***,the flame instability is increased with the increase of equivalence ratio,initial temperature and initial pressure.

关键词：层流燃烧速度空气混合物速度测定异丁醇火焰传播速度初始压力初始温度当量比

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Numerical investigation on transport characteristic of air breathing direct methanol fuel cell

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Huagong Xuebao/CIESC Journal 2011年第SUPPL. 1期62卷 66-71页

作者： Miao, Zheng Zou, Jinqiang He, Yaling Liu, Zeng State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China

A two-dimensional two-phase non-isothermal mass transport model is developed in this paper for the air breathing direct methanol fuel cell(DMFC). The self-made computer code is used to simulate the heat and mass transport characteristic which is coupled with electro-chemical reactions. The effects of temperature of the inlet methanol solution, temperature of the air, and the feeding concentration of methanol on the performance of the fuel cell are investigated. The numerical results show that the cell performance can be enhanced at a higher temperature of the inlet methanol solution and the air. Cell performance at the higher cell current densities can be improved with a higher feeding concentration of methanol. © All Rights Reserved.

关键词： Heat transfer

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Flame instability analysis of diethyl ether-air premixed mixtures at elevated pressures

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Chinese Science Bulletin 2010年第3期55卷 314-320页

作者： ZHANG Ni DI YaGe HUANG ZuoHua ZHANG ZhiYuan State Key Laboratory of Multiphase Flow in Power Engineering Xi 'an Jiaotong University Xi 'an 710049 China

Combustion characteristics of premixed diethyl ether-air mixtures were studied at different equivalence ratios and elevated initial pressures using schlieren photography and spherically propagating flame. Laminar burning velocities, Markstein number and critical radii at onset of cellular structure were obtained. The results show that an increase in initial pressure leads to a decrease in the unstretched laminar burning velocities. Laminar burning velocities give their peak values at the equivalence ratio of 1.1. Markstein number decrease with the increase of initial pressure and equivalence ratio, indicating that the instability of flame front is increased with the increase of initial pressure and equivalence ratio. The critical radii at onset of cellular flame structure are decreased with the increase of initial pressure.

关键词：不稳定性分析空气混合物火焰结构压力升高乙醚层流燃烧速度初始压力预混

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Radiation transmission simulation for volumetric solar receiver by Monte Carlo method

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Huagong Xuebao/CIESC Journal 2011年第SUPPL. 1期62卷 60-65页

作者： Cui, Fuqing He, Yaling Cheng, Zedong Li, Dong Tao, Yubing State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China

The optical model of the volumetric solar receiver has been built and corresponding solar radiation propagation process within the receiver is simulated by the Monte Carlo ray tracing method(MCRT). In the computation, the complicated photon transmission process in the SiC porous absorber is simplified as the transmission process in the statistically homogeneous and isotropic turbid media. Meanwhile, the non-uniform cylindrical coordinate grid is applied in the statistics of the absorbing energy distributions, which could reduce much computation effort compared with normal uniform grid. Based on the above model, the energy distribution of irregular macro scale porous absorber is counted. The results show that, under the given working condition, the radiation heat flux is concentrated at the top area of absorber and the maximum heat flux value is up to 2.87 × 109 W· m-3, but it decreases quickly in the sideward area. The heat flux distribution of whole porous absorber exhibits a great non-uniform characteristic, which would affect the stability and safety of receiver. © All Rights Reserved.

关键词： Monte Carlo methods

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Investigation of the transfer ionization process in collisions of partially stripped ions on He

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Chinese Physics B 2010年第6期19卷 277-282页

作者：刘会平陈熙萌欧阳晓平席发元苏光辉 State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi'an Jiaotong University School of Nuclear Science and Technology Lanzhou University

In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22-6.30 MeV Cq＋ ions and 0.25-6.35 MeV 0q＋ ions （q=1, 2, 3, 4） with the He atom separately. The cross section ratio f of transfer ionization to single electron transfer is measured, and the dependence of f on both charge state q and energy E of the projectiles is investigated. The electron-structure and the mechanisms leading to transfer ionization affect the dependence of f on q and E. Our measurements, along with other data published previously, suggest a similar dependence of f on charge state and energy of projectile for partially stripped ions over a large energy range. The maximum value of f is approximately 0.17q^0.60; the energy corresponding to maximum f is about 160q^0.60 keV/u.

关键词： ion atom collision transfer ionization single electron transfer

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Experimental investigations on combustion characteristics of syngas composed of CH_(4),CO,and H_(2)

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Frontiers of Chemical Science and Engineering 2010年第4期4卷 404-410页

作者： Qingwei FAN Shien HUI Qulan ZHOU Qinxin ZHAO Tongmo XU State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The residual gas and remained raw gas in dual gas resources polygeneration system are quite complex in components(mainly CH_(4),CO,and H_(2)),and these results to the distinguished differences in combustion *** investigations on basic combustion characteristics of syngas referred above are conducted on a laboratory-scale combustor with flame temperature and flue gas composition measured and *** air coefficient(PA),total air coefficient(TA),and components of the syngas(CS)are selected as key factors,and it is found that PA dominates mostly the ignition of syngas and NOx formation,while TA affects the flue gas temperature after high temperature region and NOx formation trend to be positive as H_(2)/CO components *** results provide references for industrial utilization.

关键词： dual gas resources polygeneration lean premixed combustion residual gas remained raw gas NOx emission

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