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A numerical investigation was performed on the reduction of the fluid forces acting on the square cylinder in the laminar flow regime with a perforated plate. The effects of geometric parameters such as the distance between the square cylinder and the perforated plate on the wake of the square cylinder were discussed. Furthermore, the flow characteristics such as the drag coefficient, lift coefficient, Strouhal number and flow pattern were obtained. It can be concluded that the drag force of the square cylinder reduces to some extent due to the addition of the perforated plate. The flow structure varies when the perforated plate is located behind the square cylinder. Moreover, the recirculation zone augments with the increase of L/D, and the vortex trace on the upper and lower surface of the square cylinder moves gradually backwards until a stable recirculation zone formed between the square cylinder and the perforated plate. 相似文献
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为了研究空芯光纤中氩气的放电特性,利用有限元软件 COMSOL Mutiphysics 基于流体模型对长为50mm 空芯光纤中的气体放电过程进行仿真,得到氩气放电过程中等离子体的主要参数分布,如电子密度、离子密度、电势、空间电荷密度、电场强度等。同时分析了气压对放电过程的影响,结果表明,气压对气体放电的影响主要体现在电子密度与阴极侧的电场强度上,随着气压的逐渐增大,阴极侧的电场强度也随之增加,阴极侧电子密度则保持不变,但在空芯光纤中央区域,电子密度的增大较为明显。 相似文献
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Numerical study on performance of perforated plate applied to cryogenic fluid flowmeter 总被引：1，自引：0，他引：1
The perforated plate is one of the effective devices for measuring flow rate accurately. In this study, a perforated plate is investigated for its characteristics, mainly including discharge coefficient C and pressure loss coefficient ζ, when applied to cryogenic fluids with the help of ANSYS Fluent. Three cryogenic fluids are studied, including liquid nitrogen (LN2), liquid oxygen (LO2), and liquid hydrogen (LH2). For comparison, two states of water are also investigated. The realizable κ-ε model with standard wall function is used to describe the turbulence and simulate the near-wall flow. The Schnerr-Sauer cavitation model is used to investigate the effect of cavitation on the performance of the perforated plate. Simulation results indicate that the upper limit of Reynolds number of the perforated plate is significantly dependent on the properties of the measured fluid when the temperatures of the fluids are set as the normal boiling point temperatures and the outlet pressures are 0.2 MPa. 相似文献
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In this paper, dynamic analyses of the swash plate vibration and pressure pulsation of an aircraft piston pump based on fluid-structure interactions (FSIs) are presented. Models of the swash plate piston pumps with three FSIs (named full FSIs and non FSI) are given. The simulation results of the discharge pressures at different rotation speeds in the synthesized pump model and experiments show good agreement. The numerical simulation results of the forces on the swash plate and the flow rate of the outlet chamber are presented and compared. The results of the two models show that the discharge pressure pulsation mostly depends on the kinematic relations of the piston slipper-shoe units (FSI-1), and is almost isolated from the swash plate vibration. The full FSIs simulation shows that the swash plate vibration is strongly influenced by the pressure pulsation through the control actuator mechanism (FSI-2) and the control valve mechanism (FSI-3), but the non FSI model does not show the same result. The full FSIs model is much more accurate in predicting the vibration of the swash plate and the pulsation of the discharge pressure than the non FSI model. 相似文献
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Study on performance of a packed bed latent heat thermal energy storage unit integrated with solar water heating system 总被引：1，自引：0，他引：1
NALLUSAMY N. SAMPATH S. VELRAJ R. 《浙江大学学报(A卷英文版)》2006,7(8):1422-1430
INTRODUCTION Efforts of rational and effective energy man-agement, as well as environmental considerations, increase the interest in using renewable energy sources, especially solar energy. Because of discrep-ancy between the energy supply and demand in solar heating applications, a thermal energy storage (TES) device has to be used for the most effective utilization of the energy source. Energy storage combined with solar collectors and photovoltaic systems have been developed over the… 相似文献
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JAIN N.C. GUPTA P. 《浙江大学学报(A卷英文版)》2006,7(3):340-346
INTRODUCTION In recent years, the subject of free convection flow has attracted the attention of a number of scholars because of its possible applications to several geophysical problems. In view of these applications, a series of investigations were made to study the flow past a vertical wall. Transpiration cooling can very effectively pro-tect certain structural elements in turbojet and rocket engines, like combustion chamber walls, exhaust nozzles or gas turbine blades from hot gases. … 相似文献
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This paper has introduced the developments of water hydraulic axial piston equipments.According to the effects of physicochemical properties of water on water hydraulic components,a novel valve plate for water hydraulic axial motor has been put forward,whose moment exerted by the fluid field between valve plate and bearing plate is balanced entirely.The material screening experiment of valve plate is done on the test rig.Through numerical simulation the effects of some geometry parameters on the performance of water hydraulic motor have been studied.The silencing grooves on the valve plate in water hydraulic motor can reduce the pressure shock and the occurrence of cavitation effectively.It is evident that the appropriate structure should change the wear status between matching paris and reduces the wear and specific pressure of the matching pairs.The specimen with the new type valve plate is used in a tool system. 相似文献
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O2电晕放电条件下能产生O/O-活性粒子,CO2电晕放电条件下同样能产生O/O-活性粒子,用CO2代替O2实现CH4的氧化偶联,研究在流动体系中,CH4/CO2的比值,原料气流速对CH4,的转化率,C2烃类选择性及得率的影响规律. 相似文献
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阐述以电磁流体和电磁流体力学理论为基础,应用硫酸铜溶液作为产生电磁流体流动现象的一种液体,用金属铜板作为产生匀强电场的极板,用密绕的长直螺线管产生匀强磁场的方法,设计出液体在电磁力作用下的流动实验方法及流动的显示方法. 相似文献
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O2电晕放电条件下能产生O／O^-活性粒子，CO2电晕放电条件下同样能产生O／O^-活性粒子，用CO2代替O2实现CH4的氧化偶联，研究在流动体系中，CH4／CO2的比值，原料气流速对CH4，的转化率，C2烃类选择性及得率的影响规律． 相似文献
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阐述以电磁流体和电磁流体力学理论为基础,应用硫酸铜溶液作为产生电磁流体流动现象的一种液体,用金属铜板作为产生匀强电场的极板,用密绕的长直螺线管产生匀强磁场的方法,设计出液体在电磁力作用下的流动实验方法及流动的显示方法. 相似文献
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3D couette flow of dusty fluid with transpiration cooling 总被引：1，自引：0，他引：1
GOVINDARAJAN A RAMAMURTHY V SUNDARAMMAL K 《浙江大学学报(A卷英文版)》2007,8(2):313-322
INTRODUCTION Transpiration cooling is a very effective process to protect certain structural elements like combustion chamber walls, exhaust nozzles, or gas turbine blades in turbojet and rocket engines, from the influence of hot gases. In view of this, Eckert (1958) obtained an exact solution of the plane couette flow with transpi-ration cooling. The problem remained 2D due to the uniform injection and suction applied at the porous plates. Flow and heat transfer along a plane wall with… 相似文献
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在介绍2010年7月汉江洪水的基础上,重点阐述了东荆河下游天星洲、王小垸两个民院扒口泄洪对潜江水位流量关系的影响,分析了扒口泄洪在本次防汛工作中的作用。 相似文献
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Jonathan K. Fernand Haleh Amanieh David J. Cox Nicole R. Dorey 《Learning & behavior》2018,46(4):472-478
The reverse-reward contingency (RRC) task involves presenting subjects with a choice between one plate containing a large amount of food and a second plate containing a small amount of food. Subjects are then required to select the smaller of the two options in order to receive the larger-magnitude reward. The RRC task is a commonly used paradigm for assessing complex cognition, such as inhibitory control, in subjects. To date, the RRC task has not been tested with pet dogs as subjects, and it may provide insights to their ability to perceive quantities of differing magnitudes. Nine dogs were tested in an RRC task involving three conditions. In Condition 1, plates of food were presented, and the dogs were allowed to consume their choice. In Condition 2, plates with different-sized symbols resembling the quantities of food in Condition 1 were presented, and dogs received food quantities of the same size as their choice (e.g., a larger-magnitude reward for selecting the plate with the larger shape). In Condition 3, the same plates were presented, but dogs received a reverse-sized quantity of food, relative to their choice (e.g., a smaller-magnitude reward for selecting the plate with the larger shape). A novel addition here to the traditional RRC task was the inclusion of a third, empty (control) plate that was present throughout all conditions, and no programmed consequences were provided when that plate was selected. Our results were consistent with the previous RRC literature: All dogs developed and maintained a preference for the larger stimulus option across conditions. The use of symbolic representations did not ameliorate performance on the RRC task. Applied implications are discussed. 相似文献
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岩巷瓦斯异常涌出是近年来矿井瓦斯涌出时常发生的一种新形式,涌出时间短,瓦斯量大,有的伴有动力现象,目前还没有规律性,治理难度较大;结合淮南矿区瓦斯异常涌出事故的实例,探讨了岩巷瓦斯异常涌出的原因,提出了相应的防治措施,对消除安全生产威胁,促进开拓进度提高,具有一定的意义. 相似文献
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流体力学是环境工程专业的一门基础课.学生常有这样的反映流体力学难学.作为讲授流体力学的教师,认为流体力学的"难"主要体现在两个方面:一是流体力学涉及的知识较广,如高等数学、大学物理等知识;二是流体力学比较抽象,理解起来有难度,加之粉笔+黑板满堂灌的教学模式单一,致使学生感到枯燥难懂,从而厌学或放弃.2011年,湖北省教育厅批准江汉大学环境工程专业实施战略性新兴产业人才(工业烟尘污染控制)培养计划.基于环境工程专业新兴产业人才培养目标要求,结合学校的课程教学改革精神,实施流体力学课程教学方法与教学模式改革.在本文中将课程改革实践中一些经验与心得分享,希望能抛砖引玉,对同行有所借鉴. 相似文献
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目前的LPR(License Plate Recognition)系统存在识别率低、速度慢和成本高等问题。将蓝底白字的车牌和金属边框、长宽比等多种特征融合,能够实现车牌的快速定位,并大大简化设计、减低成本。通过Matlab编程实现了该系统。实践证明,该系统具有造价低廉、识别速度快、准确率等优点。 相似文献