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12th International Conference on Nuclear engineering (ICONE12) - 2004

作者： Tian, Wenxi Myint, Aye Li, Zhihui Qiu, Suizheng Su, G.H. Jia, Dounan State Key Lab. Multiphase Flow P.E. 710049 Xi'an China State Key Lab. Multiphase Flow P.E. Sch. of Energy and Power Engineering Xi'An Jiaotong University 710049 Xi'an China

Prediction of dryout point is experimentally investigated with deionized water upflowing through narrow annular channel with 1.0 mm and 1.5 mm gap respectively. The annular with narrow gap is bilaterally heated by AC current power supply. The experimental conditions covered a range of pressure from 0.8 to 3.5 MPa, mass flux from 26.6 to 68.8 kg/m2 s and wall heat flux from 5.0 to 50.0 kW/m2. The location of dryout is obtained by observing a sudden rise in surface temperature, Kutateladze correlations is cited, however proved to be not a proper one for annuli gap and modified to predict the location of dryout. Considering in detail the effects of the geometry of annuli, pressure, mass flux and heat flux on dryout, an empirical correction is finally developed to predict dryout point in narrow annular gap under low flow condition which has a good agreement with experimental data.

关键词： Two phase flow

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Mathematical model and numerical simulation of helical baffles heat exchanger

Mathematical model and numerical simulation of helical baffl...

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作者： Shen, Renjie Feng, Xiao Gao, Xiaodong Department of Chemical Engineering State Key Laboratory of Multi-Phase Flow in Power Engineering Xi'An Jiaotong University Xi'an China

With the theory of the Reynolds stress model applied, a mathematical model of the flow and heat transfer of the helical baffles heat exchanger is established. The commercial software FLUENT is used to simulate the influence of helical baffles on heat transfer capability and flow resistance of helical baffle heat exchangers by unstructured grid. The numerical simulation results at the 35° helix inclination angle are compared with those of experiment. © 2004 by Begell House, Inc.

关键词： Heat exchangers

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A NOVEL SEGREGATED ALGORITHM FOR INCOMPRESSIBLE FLUID flow AND HEAT TRANSFER PROBLEMS--CLEAR (COUPLED AND LINKED EQUATIONS ALGORITHM REVISED) PART I: MATHEMATICAL FORMULATION AND SOLUTION PROCEDURE

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Numerical Heat Transfer: Part B -- Fundamentals 2004年第1期45卷 1-17页

作者： Tao, W.Q. wqtao@*** Qu, Z. G. He, Y. L. School of Energy & Power Engineering State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong University Xi''an Shaanxi People''s Republic of China

A novel segregated solution procedure for incompressible fluid flow and heat transfer problems is proposed. The new algorithm is called CLEAR (Coupled and Linked Equations Algorithm Revised). It differs from all SIMPLE-like algorithms in that it solves the improved pressure directly, rather than by adding a correction term, and no term is dropped in the derivation of the pressure equation. Thus the effects of the neighboring velocity values are fully taken into account, and the coupling between velocity and pressure is fully guaranteed, greatly enhancing the convergence rate of the iteration process. Its robustness is improved by introducing a second relaxation factor. The mathematical formulation and the solution procedure of the CLEAR algorithm are described in detail in this article. Comprehensive discussion is conducted to describe the difference between the CLEAR algorithm and all other existing algorithms of the SIMPLE family. In Part II, six numerical application examples with available numerical solutions are provided to show the feasibility of the new algorithm. [ABSTRACT FROM AUTHOR]

关键词： FLUIDS HYDROSTATICS ALGORITHMS PRESSURE HEAT transfer ENERGY transfer MATHEMATICAL formulas

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Combustion characteristics and heat release analysis of a compression ignition engine operating on a diesel/methanol blend

Combustion characteristics and heat release analysis of a co...

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作者： Huang, Z.H. Lu, H.B. Jiang, D.M. Zeng, K. Liu, B. Zhang, J.Q. Wang, X.B. State Key Lab. Multiphase Flow P.E. Xi'an Jiaotong University Xi'an China Sch. of Energy and Power Engineering Xi'an Jiaotong University Xi'an China State Key Lab. Multiphase Flow P./E. Inst. of Internal Combustion Engines Xi'an Jiaotong University Xi'an 710049 China

A stabilized diesel/methanol blend was developed and the combustion characteristics and heat release analysis of this blend was carried out in a compression ignition engine. The study showed that the increase in the methanol mass fraction will result in an increase in the heat release rate in the premixed burning phase and shorten the combustion duration of the diffusive burning phase. Ignition delay increases with the increase in the methanol mass fraction and the behaviour is more obvious at low engine load and high engine speed. The rapid-burn duration varies little with the methanol mass fraction and the total combustion duration decreases with the increase in the methanol mass fraction. At a low engine speed, the centre of heat release curve tends to be close to the top dead centre (TDC), with an increase in the methanol mass fraction at all engine loads and fuel delivery advance angles, the maximum rate of pressure rise and the maximum rate of heat release increase with the increase in the methanol mass fraction. At a high engine speed, the centre of the heat release curve closes to TDC at high engine load and will depart from TDC at low engine load. The maximum rate of pressure rise and heat release gives an increasing trend with the increase of methanol mass fraction at high engine loads. The maximum cylinder pressure increases with the increase of the methanol mass fraction. The presence of oxygen reduces the peak pressure, but the reduction was found to be insensitive to the proportion of oxygen within the 6-11 per cent range of testing.

关键词： Combustion

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Engine performance and emissions of a compression ignition engine operating on the diesel-methanol blends

Engine performance and emissions of a compression ignition e...

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作者： Huang, Z.H. Lu, H.B. Jiang, D.M. Zeng, K. Liu, B. Zhang, J.Q. Wang, X.B. State Key Lab. Multiphase Flow P. Xi'An Jiaotong University Xi'an China Sch. of Energy and Power Engineering Xi'An Jiaotong University Xi'an China Coll. of Ener. and Power Engineering Inst. of Internal Combustion Engines Xi'An Jiaotong University Xi'an 710049 China

A stabilized diesel-methanol blend was realized and a study on the performance and emissions of the diesel-methanol blend was carried out in a compression ignition engine. The study showed that the engine thermal efficiency increases and the diesel equivalent b.s.f.c. decreases with increase in the oxygen mass fraction (or methanol mass fraction) of the diesel-methanol blends due to an increased fraction of premixed combustion phase, oxygen enrichment and improvement in the diffusive combustion phase. Further increase in the fuel delivery advance angle will achieve a better engine thermal efficiency when the diesel engine is operated using the diesel-methanol fuel blends. A marked reduction in the exhaust CO and smoke can be achieved when operating with the diesel-methanol blend. There is not a large variation in the exhaust hydrocarbon with the addition of methanol in diesel fuel. NOx increases with increase in the mass of methanol added;methanol addition to diesel fuel was found to have a strong influence on the NOx concentration at high engine loads rather than at low engine loads, and a flat NOx-smoke trade-off curve exists when operating with the diesel-methanol fuel blends.

关键词： Ignition systems

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NUMERICAL SIMULATION OF WET STEAM CONDENSING flow WITH AN EULERIAN/EULERIAN MODEL

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Chinese Journal of Mechanical engineering 2003年第2期16卷 156-159页

作者： Li LiangFeng ZhenpingLi Guojunstate key laboratory of multiphase flowin power engineering,Xi’ an Jiaotong University,XI’ an 710049, China Xi' an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an 710049

Wet steam condensing flow in low-pressure steam turbine leads to efficiencylosses and blade erosions. In order to investigate this problem by numerical approach, anEulerian/Eulerian model has been developed, in which the wet steam is regarded as mixture comprisingtwo coupled systems: the vapor phase and the liquid phase. These two systems are both described byconservation equations. High resolution TVD scheme is employed to capture condensing phenomena inwet steam flow. This model has been validated by numerical simulations of condensing flows in 1D and2D nozzles. Compared with experimental data, a good agreement is observed. This Eulerian/Eulerianmodel can be extended to 3D calculation of condensing flow.

关键词： wet steam condensing flow numerical simulation eulerian/eulerian model

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Simulation of flow across complicated domain between tube bundles by the discrete vortex method

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自然科学进展(英文版) 2003年第3期13卷 213-218页

作者： CHEN Bin Guo Liejin Yang Xiaogang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an J iaotong University Xi'an 710049 China

On the basis of the analysis of numerical simulation methods for the complicated domain between tube bundles, an improved Lagragian discrete vortex method (DVM) and corresponding algorithm are put forward to solve the practical difficulties of flow across tube bundles. With this method the amount of vortices can be reduced considerably, which makes quick calculation possible. Applied to the practical configuration of horizontal tube bundles, the DVM simulation is carried out and compared with the experimental results. Both the transient flow field and the profile of mean velocity and fluctuations are in good agreement with experimental results, which indicate that the DVM is suitable for the simulation of single-phase flow across tube bundles.

关键词： tube bundles discrete vortex method numerical simulation

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An Experimental Study on the flow Characteristics of OilWater Two-Phase flow in Horizontal Straight Pipes

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Chinese Journal of Chemical engineering 2003年第5期11卷 491-496页

作者：刘文红郭烈锦吴铁军张西民 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The flow patterns and their transitions of oil-water two-phase flow in horizontal pipes were studied. The experiments were conducted in two kinds of horizontal tubes, made of plexiglas pipe and stainless steel pipe with 40 mm ID respectively. No. 46 mechanical oil and tap water were used as working fluids. The superflcial velocity ranges of oil and water were: 0.04-1.2m·s-1 and 0.04-2.2m·s-1, respectively. The flow patterns were identified by visualization and by transient fluctuation signals of differential pressure drop. The flow patterns were defined according to the relative distribution of oil and water phases in the pipes. flow pattern maps were obtained for both pipelines. In addition, semi-theoretical transition criteria for the flow patterns were proposed, and the proposed transitional criteria are in reasonable agreement with available data in liquid-liquid systems.

关键词： oil-water two-phase flow horizontal pipe flow pattern transition criterion

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A Hydrodynamic Modei for Slug Frequency in Horizontal Gas-Liquid Two-Phase flow

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Chinese Journal of Chemical engineering 2003年第5期11卷 508-514页

作者：刘磊孙贺东胡志华周芳德 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The prediction of slug frequency has important significance on gas-liquid two-phase flow. A hydrody-namic modei was put forward to evaluate slug frequency for horizontal two-phase flow, based on the dependence of slug frequency on the frequency of unstable interfacial wave. Using air and water, experimental verification of the modei was carried out in a large range of flow parameters. Six electrical probes were installed at different positions of a horizontal plexiglass pipe to detect slug frequency development. The pipe is 30m long and its inner diameter is 24 mm. It is observed experimentally that the interfacial wave frequency at the inlet is about l to 3 times the frequency of stable slug. The slug frequencies predicted by the modei fit well with Tronconi (1990) modei and the experimental data. The combination of the hydrodynamic modei and the experimental data results in a conclusion that the frequency of equilibrium liquid slug is approximately half the miniraum frequency of interfacial wave.

关键词： gas-liquid flow two-phase flow interfacial wave hydrodynamic model slug frequency

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Liquid mean velocity and turbulence in a horizontal air-water bubbly flow

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Nuclear Science and Techniques 2003年第2期14卷 149-152页

作者： YANG Jian, ZHANG Ming-Yuan, ZHANG Chao-Jie, SU Yu-Liang (The state key Lab of multiphase flow in power engineering, Xi ’an Jiaotong University, Xi ’an 710049) Xi'an Jiaotong University The State Key Lab of Multiphase Flow in Power Engineering Xi'an 710049

The liquid phase turbulent structure of an air-water bubbly horizontal flow in a circular pipe has been investigated experimentally. Three-dimensional measurements were implemented with two "X" type probes oriented in different planes, and local liquid-phase velocities and turbulent stresses were simultaneously obtained. Systematic measurements were conducted covering a range of local void fraction from 0 to 11.7%. The important experiment results and parametric trends are summarized and discussed.

关键词：湍流气泡流液体速度热膜风速测定法

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