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二维流化床内垂直向上射流影响区的试验研究 总被引:1,自引:1,他引:0
提出了射流影响区的概念,利用图像处理技术和统计方法得到了射流在射流影响区出现的几率以及射流影响区的范围。研究了流化数、射流初始速度以及颗粒平均粒径对射流影响区的影响。结果表明:射流影响区的范围随流化数、射流初始速度以及颗粒平均粒径的增加而扩大。 相似文献
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在Ф0 .5m× 8m大型双射流流化床中 ,通过摄像、放像逐帧分析法和sthVCD软件分析录像转换的VCD ,得到了不同管间距下双射流典型的运动图像 .同时研究了两射流独立存在区、过渡区和射流合并区 3种流型的相互转变 ,得出了流型转变的关系式 .不同射流管间距下相同射流气速的射流深度相比 ,管间距减小则射流深度减小 ;在较小的管间距和相对高的射流气速下 ,两射流在射流深度之内始终合并 ,表现为射流合并高度 .得出了射流深度、射流合并高度的定量关系式 .分数维关联维数表明大型双射流流化床是一个确定性混沌系统 ,考查了管间距、静床高度对关联维数的影响 相似文献
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本文研究在蓄热室底部后墙设置射流以提高蓄热室内上升气流分布均匀性,对设置射流的影响因素、喷射器出口大小、安装位置及喷射器流量(出口速度)等因素进行了研究,确定出设置射流的最佳方案。 相似文献
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Seven distributors with different configurations are designed and optimized by constructal approach. Their flow distribution performance and energy dissipation are investigated and compared by computational fluid dynamics (CFD) simulation. The reliability of CFD simulation is verified by experiments on the distributor that has all distributing rectangle channels on a plate. The results show that the symmetry of the distributing channels has decisive influence on the performance of flow distribution. Increasing the generations of channel branching will improve the flow distribution uniformity, but on the other hand increase the energy dissipation. Among all the seven constructal distributors, the distributor that has dichotomy configuration, Y-type junctions and straight intercon-necting channels, is recommended for its better flow distribution performance and less energy dissipation. 相似文献
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设备内部气体可能存在湍流流动状态,设备壁面形成沟槽形式可能会对原流动状态产生影响从而影响设备性能。以前相关研究很少,但设备内部气体是否存在湍流流动状态,流动状态改变是否会对设备性能产生影响还需要进一步研究。为研究壁面形成沟槽形式对原湍流流动产生的影响,对流动状态变化前后沿壁面温度分布进行了计算,采用脉动温度符合一定概率分布的方法计算了脉动温度,对流动状态变化时温度场变化情况进行了分析。 相似文献
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提出了以最密堆积作为评价水煤膏粒度配比优劣的指标并研究了煤粉颗粒在不同粗细比下的自然堆积体积和析水率,得出了徐州混煤和贾汪烟煤(粒度0~5mm)的最佳配比,该结果在我所水煤膏流动试验台上得到验证。 相似文献
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本文涉及一种新型的多流道熔体分配机头,其分配流道的设计能够尽可能保证熔体流动路径的一致性。运用基于有限元的CFD分析软件Polyflow对熔体进行了模拟计算,并运用后处理软件Fieldview,对三种不同流道的分配机头模型的压力场、速度场及黏度场进行了分析比较,得出了一些有关该新型分配机头的设计要点。 相似文献
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蒸发器换热管间制冷剂的分配不均会导致其制冷能力的下降。建立了管壳式蒸发器和分流板三维模型,模拟研究了分流板的位置、开孔大小、开孔数量和开孔结构对R410A均分性能的影响。模拟结果表明,分流板各参数对制冷剂均流效果有显著影响。在不同入口流速工况下,不均匀度随分流板向蒸发器入口端的移动而下降且降幅逐渐变缓;不均匀度随开孔直径的增大而上升,随开孔数量的增大而下降并达到稳定;经优化分流板开孔结构,上下小孔结构的均分性能相比等圆孔结构可提高21.4%。搭建了蒸发器流量分配实验台,通过实验验证了模拟得出的流量分配规律以及分流板对流体均分性能的提升,说明根据流量分布特点优化分流板开孔结构能有效提升制冷剂的均流效果。 相似文献
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由于板翅式换热器结构的复杂性,存在着内部流动速度分布的不均匀性,从而引起其换热效率下降,影响了换热器的整体效能.引起流动速度分布不均匀的因素是多方面的,针对不同导流片结构参数(h/H)对导流片导流性能的影响进行了深入研究,发现导流片结构参数对换热器内部流动速度分布不均匀性的影响主要表现在总管流动方向上,通过改变板翅式换热器导流片的结构参数可有效地改善换热器内部物流在总管流动方向上的分配情况,从而有效地改善换热器内部流动速度的分布.研究结果对板翅式换热器的优化设计具有重要意义. 相似文献
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The gel effect will bring a violent increase of conversion for methyl methacrylate (MMA) polymerization in a short time. It will be very dangerous for the reactor, as it causes an increase of molecular weight and broadens the molecular weight distribution. To unify the kinetics, molecular weight, and its distribution, on the basis of the mathematical models for semibatch polymerization of MMA, three controlled objectives that are the heat load distribution index, the change in molecular weight, and molecular weight distribution index are presented. Three materials (monomer, solvent, and chain transfer agent) and their flow rate and feeding mode are analyzed for the open control of kinetics, molecular weight, and its distribution. The optimum flow rate and mode are obtained. The heat load distribution index and molecular weight distribution index are even less than 2.0 and 2.2, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4399–4405, 2006 相似文献
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The flow distribution through a plate‐fin heat exchanger is studied by using a computational fluid dynamics (CFD) code, FLUENT. The flow distribution through any heat exchanger affects its performance. In designing a heat exchanger, it is assumed that the fluid is uniformly distributed through the heat exchanger core. In practice, however, it is impossible to distribute fluid uniformly, because of an improper inlet configuration, imperfect design, and a complex heat transfer process. The CFD simulation of the flow distribution in the header of a conventional plate‐fin heat exchanger is presented. It is found that the flow maldistribution is very serious in the y‐direction of the header. A modified header is proposed and simulated using CFD. The modified header configuration has a more uniform flow distribution than the conventional header configuration. Hence, the efficiency of the modified heat exchanger is seen to be higher than that of the conventional heat exchanger. 相似文献
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Local mass transport effects in the FM01 laboratory electrolyser 总被引:1,自引:0,他引:1
C. J. Brown D. Pletcher F. C. Walsh J. K. Hammond D. Robinson 《Journal of Applied Electrochemistry》1992,22(7):613-619
A number of patterns of segmented line electrodes have been manufactured using copper printed circuit board technology. These segmented electrodes have been used to investigate local mass transport effects in ICI's FM01-LC parallel plate electrolyser. It is shown that in the absence of a turbulence promoter the current distribution is uneven. Along the direction of electrolyte flow, a tertiary current distribution is observed. In addition, close to the cell entrance, an uneven current distribution occurs perpendicular to the direction of electrolyte flow; this reflects the design of the electrolyte distributor. With a turbulence promoter the current distribution is more even and the entry effects are much reduced. The turbulence promoter can, however, impose its own pattern on the current distribution perpendicular to the flow. 相似文献