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Numerical study of EGR effects on reducing the pressure rise rate of HCCI engine combustion

中国高等学校学术文摘·能源与动力工程 2010年第3期4卷 376-385页

作者： Gen CHEN Norimasa IIDA Zuohua HUANG State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Graduate School of Science and Technology Keio University Japan Graduate School of Science and Technology Keio University Japan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

The effects of the inert components of exhaust gas recirculation (EGR) gas on reducing the pressure rise rate of homogeneous charge compression ignition engine combustion were investigated numerically by utilizing the CHEMKIN II package and its SENKIN code, as well as Curran's dimethyl ether reaction scheme. Calculations were conducted under constant volume combustion and engine combustion (one compression and one expansion only, respectively) conditions. Results show that with constant fuel amount and initial temperature and pressure, as EGR ratio increases, combustion timings are retarded and the duration of thermal ignition preparation extends non-linearly; peak values of pressure, pressure rising rate (PRR), and temperature decrease; and peak values of heat release rate in both low temperature heat release (LTHR) and high temperature heat release decrease. Moreover, maximum PRR decreases as CA50 is retarded. With constant fuel amount, mixtures with different EGR ratios can obtain the same CA50 by adjusting the initial temperature. Under the same CA50, as EGR ratio increases, the LTHR timing is advanced and the duration of thermal ignition preparation is extended. Maximum PRR is almost constant with the fixed CA50 despite the change in EGR ratio, indicating that the influence of EGR dilution on chemical reaction rate is offset by other factors. Further investigation on the mechanism of this phenomenon is needed.

关键词： HCCI engine combustion EGR DME CA50 PRR

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LDV measurements of a turbulent channel flow with smooth and rough surfaces

LDV measurements of a turbulent channel flow with smooth and...

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17th Australasian Fluid Mechanics Conference 2010, 17AFMC

作者： Zhang, Y.B. Che, D.F. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

ISBN: (纸本)9781617829130

Detailed Laser-Doppler Velocimeter (LDV) measurements have been carried out in a turbulent rectangular channel flow with smooth and rough surfaces at different Reynolds numbers. The measured distributions of turbulence statistics across the half channel height at different wall conditions, including mean velocity, turbulence intensity, skewness factor, flatness factor and Reynolds shear stress are all reported and compared. The turbulent statistical quantities on different surfaces exhibit significant differences in both the inner and the outer region, which suggests that the roughness element has an important role on turbulent flow structure extending into the whole layer. There is a significant increase in the streamwise turbulence intensity and a slight increase in the normal turbulence intensity and the Reynolds shear stress over the rough surface. The profiles of the streamwise skewness factor become flatter over the rough walls, while the flatness factor distributions are nearly the same for different surfaces.

关键词： Laser Doppler velocimeters

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A Novel One-step Hydrothermal Method for the Preparation of Cd1-xZnxS/Titanate Nanotubes Composites for Photocatalytic Hydrogen Production 18

A Novel One-step Hydrothermal Method for the Preparation of ...

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18th World Hydrogen Energy Conference, WHEC 2010

作者： Chen, Yubin Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University China

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Numerical simulations of the discontinuous progression of cerebral aneurysms based on fluid-structure interactions study

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Science China(Physics,Mechanics & Astronomy) 2010年第5期53卷 944-953页

作者： MA XiaoQi1,WANG YueShe1,YU FangJun1 & WANG GuoXiang1,2 1 state key laboratory of multiphase flow in Power Engineering,Xi’an Jiaotong University,Xi’an 710049,China 2 Department of Mechanical Engineering,The University of Akron,Akron,OH 44325-3903,USA 1. State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China2. Department of Mechanical Engineering The University of Akron Akron OH 44325-3903 USA

Investigations into the characteristics of hemodynamics will provide a better understanding of the pathology of cerebral aneurysms for *** this work,a steady state discontinuous-growth model of the cerebral aneurysms was *** the assumption of the fluid-structure interaction between the wall of blood vessel and blood,a fluid-structure coupling numerical simulation for this model was built using software ANSYS and *** simulation results showed that as the aneurysm volume increased,a blood flow vortex came forth,the vortex region became asymptotically larger,and eddy density became gradually stronger in *** the emergence of the vortex region,the blood flow in the vicinity of the downstream in the aneurysms volume turned into bifurcated flow,and the location of the flow bifurcated point was shifted with the aneurysm volume growing while directions of the shear stress applied to two sides of the bifurcated point were *** Von Mises stress distribution along the wall of aneurysm volume decreased in the prior period and increased gradually in the later *** maximum stress was in the neck of the volume and the minimum was on the distal end in the whole process of *** was shown that as the aneurysm increased the maximum deformation location of the aneurysm,vertical to the streamline,was transferred from the distal end of the aneurysm to its neck,then back to its distal end of the aneurysm again.

关键词： cerebral aneurysm fluid-structure interaction wall shear stress discontinuous progression

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Impacts of different diameter combinations on the temperature of a crude oil pipeline when colocating with a products pipeline

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中国高等学校学术文摘·能源与动力工程 2010年第2期4卷 192-197页

作者： Bo YU Yue SHI Xin LIU Jinjun ZHANG Jinjia WEI Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum BeijingBeijing 102249China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

In order to show the effects of different diameter combinations on crude oil temperature when a crude oil pipeline and a products pipeline are laid in one trench, four typical diameter combinations are selected to conduct numerical simulation. After a series of calculations, the minimum mean temperature difference and the maximum temperature difference of the crude oil along the pipelines are obtained. In real pipeline constructions, the effects of other diameter combinations on crude oil temperature can be predicted by the method of linear interpolation to calculate results of the four diameter combinations obtained in this study.

关键词： technology of laying two pipelines in one trench diameter combinations crude oil temperature pipeline interval

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Catalytic combustion of ventilation air methane in a reverse-flow reactor

Catalytic combustion of ventilation air methane in a reverse...

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作者： Wang, Yikun Man, Chengbo Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xian Jiaotong University Xian 710049 China

This paper describes an experimental study on the catalytic combustion of ventilation air methane in a vertical reactor. The mixture of natural gas and compressed air was used in the experiments, and the combustion products were analyzed by the Fourier transform infrared (FTIR) gas analyzer. The effects of the initial temperature, cycle time, feed gas concentration, and space velocity were studied. The experimental results show that the reactor could run under a wide range of operating conditions with self-sustaining operation and high methane conversion. Besides, it could even run with a feed gas concentration as low as 0.13 vol % without generation of CO and NOx, which has not been achieved in previous studies. The optimization of operating parameter combination increases the stability and efficiency of combustion. Different from the previous studies, the present research shows that the temperature profile of the cyclic steady state is not affected by the initial temperature. In addition, the methane conversion and reaction zone change during the process of the reaction. Thus, there is a limitation about the employment of a gas chromatograph (GC) to measure the methane concentration. Moreover, the presence of natural convection makes the temperature profiles of the cycle steady state asymmetrical. © 2010 American Chemical Society.

关键词： Compressed air

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Gas‐Liquid Two‐Phase flow Distribution Using Phase Separation Method

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AIP Conference Proceedings 2010年第1期1207卷 172-177页

作者： B. D. Zhang D. Liu D. Wang State Key Laboratory of Multiphase Flow Xi’an Jiaotong University China

A method for gas‐liquid two‐phase flow distribution is proposed in this study, which can be called the phase separation method. The advantage of the new method is that it converts two‐phase flow distribution into single‐phase distribution, which overcomes the problem of phase splitting in the distribution process of two‐phase flow radically, and an equal quality distribution is guaranteed. At first, separate the mixture of gas and liquid into single or near single phase fluids by enhancing phase splitting in distributor, then distribute the single gas and liquid flow respectively as required, finally recombine each couple of gas and liquid stream respectively to form a two phase stream exiting a branch. Experiments were conducted in an air‐water multiphase flow test loop. The flow pattern in the experiments included stratified flow, wave flow, slug flow and a part of annular flow. The experimental results show that the phase separation method and apparatus could be feasible to make an equal quality distribution and the deviation of stream quality among the branches is less than 1.6%.

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Experimental investigation and modeling of mass transfer characteristics in a double‐contact flow absorber

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AIP Conference Proceedings 2010年第1期1207卷 211-218页

作者： N. Li Q. L. Zhou D. J. Kong T. M. Xu S. E. Hui State Key Laboratory of Multiphase Flow Xi’an Jiaotong University China

A double‐contact‐flow absorber comprising spray nozzle array with new flow p attern has been proposed, modeled and tested with CaCO3 as sorbent. The flow characteristic of different scale absorber has been investigated, and the practical be d height coe fficient can be expressed by a exponent function when Froude number is used as independent variable. Various parameters such as liq uid flow rate, flue gas flo w rate and different nozzle array pattern s influencing desu lfurization rate have been tested in s mall sc ale equipment. Under the m oderate condition em ployed, the desulfurization efficiency can reach a high level above 95%. A model has been established to describe th e heat and m ass transfer process in double‐conta ct‐flow absorber, especially, a method to estimate the contact area between gas and liquid.

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The concentration measurement of Biomass/Pulverized Coal/Air threephase flow based on electrostatic and capacitive method 6

The concentration measurement of Biomass/Pulverized Coal/Air...

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6th World Congress in Industrial Process Tomography

作者： Zhang, Juan Hu, Hongli Dong, Jun Zhang, Xiao Xu, Tongmo State Key Laboratory of Power Equipment and Electrical Insulation Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Power Engineering and Multiphase Flow Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9780853163220

A system for the phase concentration measurement of biomass/pulverized coal/air threephase flow based on electrostatic sensor and capacitive sensor data fusion in pneumatic conveying fuel system at power stations is developed. Because electrostatic sensor is more sensitive to dilute pulverized coal, while capacitive sensor to biomass, they are used in the measurement of biomass concentration and pulverized coal concentration in biomass/pulverized coal/air threephase flow. flow regimes are identified by HHT of the electrostatic sensor output signal. Under the certain flow regime identified, the dual regression analysis method is applied to work out the biomass concentration and the pulverized coal concentration. The experiment result indicates that the system has high linearity up to 5%. © 2010, International Society for Industrial Process Tomography. All rights reserved.

关键词： Biomass

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Phase identification by a novel needle-contact capacitance probe in gas-liquid two-phase flows

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Nuclear Science and Techniques 2010年第5期21卷 316-320页

作者： HUANG Shanfang LU Jun ZHANG Bingdong WANG Dong Department of Engineering Physics Tsinghua University Beijing 100084 China State Key Laboratory of Multiphase Flow in Power Engineering Xi 'an Jiaotong University Xi'an 710049 China Beijing Aerospace Institute for Metrology and Measurement Technology Beijing 100076 China

In this paper,we propose a novel probe to identify phases in any two-phase flows where one phase is conductive and the other *** can further obtain many parameters such as void fraction,bubble velocity,and interfacial area *** with the traditional probe,the novel probe has unique advantages that it is less dependent on water conductance or distance between the electrodes,and that the amplitude is bigger between high and low *** analyses showed that the measurement error became higher when water conductance decreases or distance increases,which is consistent with the theoretical *** results showed that the output signal kept constant with salt content of 0-5% and electrode distance of 0-30 mm in tap *** level difference was up to 6.4 V,resulting in identifying two phases *** traces of phase identification were completely consistent with the flow structures.

关键词：气液两相流探头接触式鉴定一阶电导电极水电导率气泡速度

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