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1.
本文采用轴对称情形下内外Stokes流动的Sampson级数解求出了轴对称拉伸流动中大表面张力下球形液滴stokes流动的准确解。该准确解表达式简单且为有限形式。文中详细分析了流线谱,粘度比对内外流的影响以及内流的速度分布和压力分布。  相似文献   

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本文在计算任意形状流道中二维粘性不可压缩定常流动的流线迭代法的基础上,进一步提出一种隐式流线迭代法。本文首先导出粘性不可压缩流动的新的总压方程,然后采用隐式方法对该总压方程进行数值计算。算例计算表明了本文所提出的这种隐式流线迭代法能提高收敛速度和减少计算时间。  相似文献   

4.
本文针对火电厂粉煤灰高浓度管道水力输送非均质流管流中切应力及流速分布的基础上,提出了非均质流高浓度管流中层流、紊流阻力公式,通过实测资料验证,理论计算与实测资料之间关系比较一致,说明模型设想及理论公式是合理的。  相似文献   

5.
含植物明渠流动分区和特征尺度研究进展   总被引:1,自引:0,他引:1  
植物是生态河流必不可少的要素之一。植物的存在,改变了水流的紊流结构。由于流动沿垂向具有较强的不均匀性,对于含植物明渠紊流统计特性的描述,至今未有公认的、统一的沿水深分布表达形式。因此,对含植物明渠流动分区和各区特征尺度的研究越来越受到重视。本文回顾了无植物明渠和含植物明渠流动分区及特征尺度研究的主要成果,重点对基于流速分布和紊流结构两种方法确定的分区和特征尺度进行了分析和总结。指出将涡结构与流动特性参数分布规律相结合进行流动分区,在各区确定合适的特征尺度,进一步探究分区界限及流动特征尺度的影响因素及具体影响,建立普适的紊流统计特性分布规律是今后含植物明渠紊流结构研究的重要内容和趋势。  相似文献   

6.
Low concentration sediment-laden flow is usually involved in water conservancy, environmental protection, navigation and so on. In this article, a mathematical model for low-concentration sediment-laden flow was suggested based on the two-phase flow theory, and a solving scheme for the mathematical model in curvilinear grids was worked out. The observed data in the Zhang River in China was used for the verification of the model, and the calculated results of the water level, velocity and river bed deformation are in agreement with the observed ones.  相似文献   

7.
Flow patterns of liquid-gas two-phase flow were experimentally investigated. The experiments were carried out in both vertical and horizontal capillary tubes having inner diameters of 1.60 mm. The working liquid was the mixture of water and Sodium Dodecyl Benzoyl Sulfate (SDBS). The working gas was Nitrogen. For the water/SDBS mixture-gas flow in the vertical capillary tube, flow-pattern transitions occurred at lower flow velocities than those for the water-gas flow in the same tube. For the water/SDBS mixture-gas flow in the horizontal capillary tube, surface tension had little effect on the bubbly-intermittent transition and had only slight effect on the plug-slug and slug-annular transitions. However, surface tension had significant effect on the wavy stratified flow regime. The wavy stratified flow regime of water/SDBS mixture-gas flow expanded compared with that of water-gas.  相似文献   

8.
杨海艳 《山西水利》2013,(12):20-21
以离心泵为例,通过试验模拟方法对离心泵中流体的非定常流动状态进行研究,得出泵系统中的瞬变特征所产生的非定常流动主要与泵系统中出现的非调节工况有关,同时泵系统的惯性及容性的相对强弱决定了非调节工况下泵系统的瞬变强度的结论.  相似文献   

9.
BINGHAM液体在圆管中流动的稳定性   总被引:2,自引:1,他引:1  
将涡流模型[1]推广应用于研究一类带屈服应力的液体-Bingham液体在圆管中流动的稳定性,建立了判别其流动状态的判据──广义临界雷诺数Rec。同时将Misha—Trpathi[2]和HanKs[3]流动稳定性理论用于该问题的研究。各模型的研究结果与Froishteter&Vinogradov提供的实验数据[4]进行了比较。理论分析与实验资料表明:涡流模型对于非牛顿流体的流动稳定性研究具有较好的适应性与准确性  相似文献   

10.
张攀峰  王晋军  展京霞 《水利学报》2002,33(3):0039-0043
在风洞中研究了扰流片高度和底部间隙对平板扰流片引起的底板壁面压力分布的影响。用电子扫描阀测量的压力分布结果表明,底部没有间隙时,扰流片高度的增加不影响扰流片前后分离点、再附点以及主涡相对位置的变化;而下游回流区二次涡的相对高度随着扰流片高度的增加而增加,导致该区域无量纲压力系数绝对值减小。底部相对间隙在0.8~2.0之间时,扰流片高度小于边界层厚度时的壁面平均压力比扰流片高度大于边界层厚度时小30%左右。底部间隙对各种扰流片引起的壁面压力分布的影响趋势完全相似。  相似文献   

11.
通过田间试验研究探讨了土壤水非均匀流动特性及其描述方法。采用染色示踪剂观察了土壤水非均匀流动模式,并采用功率谱分析方法探讨了流动的尺度特性。应用弥 散聚合限制模型(DLA)模拟非均匀流动模式。研究结果表明常耕地和废弃地条件下的非均匀流动的流动模式、染色比例、含水率变化量以及溶液浓度随深度的变化规律明显不同。功率谱分析表明,非均匀流动具有尺度相似性。弥散聚合限制模型中,粒子通过随机移动生成分形结构体,通过改变移动概率和进行结构分层使模型产生的流动形状与实际流动模式一致,说明DLA模型能较好的模拟非均匀流动,同时表明土壤非均匀流动具有分形特征。  相似文献   

12.
异齿裂腹鱼通过鱼道内流速障碍能力及行为   总被引:1,自引:0,他引:1  
鱼类通过流速障碍能力是鱼道设计的主要生态指标,目前国内外主要使用封闭游泳水槽进行鱼类各种游泳速度指标及游泳行为研究,其水流流态及鱼类游泳行为与鱼类通过鱼道的实际状态有较大的差距,有必要结合鱼类游泳速度指标来探索能够更加准确量化鱼类通过鱼道流场的游泳能力测试方法。首先,在封闭游泳水槽中通过速度递增法测得异齿裂腹鱼临界游泳速度(101.01±20.86 cm/s)和突进游泳速度(196.94±21.80 cm/s);然后,以临界游泳速度和藏木水电站鱼道竖缝流速(110.00 cm/s)为参考,通过在开放游泳水槽内加不同束窄梯形体,形成类竖缝式鱼道的鱼类自主游泳能力测试水槽,开展两种底坡条件下4级短竖缝(工况1和工况2竖缝流速为101.55±14.87 cm/s、114.63±24.28 cm/s,竖缝顺水流长度均为40 cm)和单级长竖缝(工况3竖缝流速为137.45±17.63 cm/s、竖缝顺水流长度为160 cm)下试验鱼通过流速障碍能力和行为研究。试验结果表明:工况1、工况2下试验鱼通过4级竖缝成功率分别为82.05%、84.62%,通过流速大于临界游泳速度的竖缝时,持续爆发游泳时间为0.52±0.34 s;工况3下93.33%试验鱼以209.43±21.76 cm/s游泳速度成功通过单级长竖缝;3种工况下试验鱼通过流速大于临界游泳速度的竖缝时,以与突进游泳速度无显著性差异(P0.05)的恒定游泳速度(214.01±30.64 cm/s)上溯。鱼类游泳轨迹与流场耦合分析表明:鱼类上溯所需时间及路径长度与其选择的游泳路径密切相关,试验鱼通过借助回流区同向水流推动,增加上溯效率。本文研究方法及研究结论可为鱼道设计、改造、评价提供依据。  相似文献   

13.
Based on established numerical methods and hydrodynamic performance testing facilities, CFD technique are applied to improve the design of the implantable axial flow blood pump and the flow analysis. (1) Applying brushless machine magnet steel, reducing its thickness while increasing the length, the flow channel's cross-section is increased, with no space connection between the large and the small rotators, and with a cone transition segment from the bearing to the principal axis, the flow is made smoother. The rotating speed is lowered by 1000 rpm – 1200 rpm under the same flow rate and pressure head, and thus the hemolysis can be avoided. (2) Different outlet stator guiding vanes are selected for the same blood pump for analyses of hydrodynamic performances and flow fields. An excellent design not only can regulate the rotating flow field into an axial one, reduce the circulation loss and improve the pump efficiency, but also can avoid backflow, vortex and secondary flow at the pump outlet, and thus the thrombus can be prevented. (3) The calf live tests show that some residual clots exist at the inner wall of the outlet connection bends, which are analyzed and explained by CFD techniques and the corresponding improvements are proposed. All results are verified by hydrodynamic performance tests and PIV flow field tests, and consistent conclusions are obtained.  相似文献   

14.
During the design and construction of the deepwater offshore basin, its current generation system is considered to be one of the key technologies. In this article, the state-of-the-art deepwater offshore basin at Shanghai Jiaotong University was examined as a case study. Different 3-D numerical models of the current generation system were developed and calculated. The uniformity of flow field in the basin, such as horizontal and vertical current velocity profiles, were calculated in detail. Besides, a 1:10 scaled model test was also carried out. The current velocities at different locations in the basin were measured and compared with the calculated results. It is concluded that satisfactory agreement can be resulted between the numerical simulation and model test. In addition, it is suggested that transition sections and turning vanes need to be set in inflow and outflow culverts to improve the uniformity of flow field in the basin. And the hydraulic performance of the deepwater current generation system can meet the requirements of model tests in deep water.  相似文献   

15.
1. INTRODUCTION The emitter is a device used to dissipate pressure and to discharge water at a constant rate by dissipating the energy when pressured water flows through its narrow and long internal path structure or micro-orifice. It is the main componen…  相似文献   

16.
1.INTRODUCTIONTherearemanyhydraulicturbinesoperatedinsiltladenriversintheworld.Thepresenceofsolidparticlesintheflowoftencauseabrasivedegradationofcertainpartsofthehydraulicturbinewhichareespeciallyexposedtotheflow.Theerosivewearduetohydroabrasiondependsprimarilyonthesurfacematerialandonthematerialoftheabrasiveparticlesinwater.Thefluiddynamicsoftheparticlemotionalsoplayaveryimportantroleinthistribologicalsystem.Therelativevelocityofparticlesandthefrequencyofimpactarekeyfactorsindetermining…  相似文献   

17.
1. INTRODUCTIONTheproblemofsedimenttransportnearcoastalregionisofgreatimportanceforthesiltationinnavigationalfairways,harbordocksandthechangesinbeachprofileandcoastalmorphology.Underpracticalconditions,dynamicenvironmentisverycomplexbecausethewaveandcurrentarerandomand,theirpropagatingdirectionsarealsouncertain.Sothestudyofsedimenttransportinanirregularwave-currentcoexistentfieldismoreimportantthanthatinpurewaveorpurecurrentfield.Inrecentyears,manyempiricalformulaswereproposedtoexpressth…  相似文献   

18.
在河工模型试验中, 粒子图像表面流场测量方法得到了广泛应用。研制了一种新型分布式表面流场测量系统,该系统采用局域网组网与光纤传输相结合,通过POE千兆交换机与高清智能一体化工业摄像机相连,显著降低了布线复杂度,具有系统传输距离远、布设简单、集成度高、可扩展性强等优点。系统具备可视化全自动采集、可视化错误矢量剔除、导出多种数据格式,生成流场等值线图、流线等功能。在系统研制基础上,提出了一种对粒子图像表面流场测量系统进行精度检测的新方法,通过精确控制匀速旋转平台模拟水流运动,将表面流场测量系统实测数据与旋转平台上各点精确数据进行对比检测,检测结果表明,研制的表面流场测量系统测量误差小于5%,已在长江河口模型等多个大型河工模型中得到成功应用。  相似文献   

19.
针对不同水文气象条件下湖泊真实流场描述的难题,通过在洪泽湖主要入口分别投放GPS示踪器,实现了对湖泊表层水流轨迹、方向的实时监测,形成洪泽湖初步流场图。野外示踪实验结果表明:流经湖泊中心区域的水流运动轨迹均为自西向东的曲线;入湖流量较小时水流难以进入湖泊中心流场,入湖流量较大时流速空间分布不均,流场较复杂;小流量入湖条件下水流运动受到湖泊表面风场的影响,流量较大时水流流动的主要影响因素为湖泊自身的流场。同时,构建了不同入湖流量条件下的洪泽湖二维水动力数值模型,水动力模型模拟的流场分布基本符合水流质点GPS示踪实验的结果,两者拟合较好。本次研究揭示了洪泽湖的真实流场,基于GPS的示踪方法可用于分析河流湖泊的水动力空间变化,为泥沙、污染物质的输移和扩散提供了重要参考依据。  相似文献   

20.
THE ANALYSIS OF THE STEADY FLOW IN THE FLOW CHAMBER   总被引:3,自引:1,他引:2  
A flow chamber whose length and width are far larger than its own height was widely used to study cell's mechanical behavior in vitro , especially the cell's adhesion property. The paper analyzed the flow field of the flow chamber in detail, and gave the analytical expressions of the velocity, pressure and shear stress when the fluid flowed in and out the chamber through a small crevice. Then, full and clear discussion of flow field was made. Also the velocity field was measured by an Ultrasonic Doppler Velocity-metre. It was found that the experimental values coincided with the theoretical values. These results were important to study the cell's mechanical behavior in vitro .  相似文献   

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