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Horseshoe vortex formation around cylinders attached to an end-wall

机译:附在端壁上的圆柱体周围的马蹄涡形成

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Experiments have been performed to study the behaviour of the end wall boundary layers for anumber of wall-mounted cylinders. Surface flow visualisation using oil smear has been combinedwith a detailed measurement programme using two-component PIV.One aim of the investigation is to examine the possibility that the secondary flow losses generated bythe short support struts that are a common feature in turbo-machines can be minimised by carefulchoice of the cross-section of the cylinder. This idea was originally suggested by a theoretical analysisHawthorne (1951) and was studied experimentally by Williams (1970). The intention is to re-examinethe problem using the more sophisticated measurement techniques now available. A further objectiveof the investigation is to produce a data bank of high quality experimental data for the validation ofcomputational flow models.Experiments have been performed in two different wind tunnels. The first of these has a rectangularcross-section which is 4.68 wide × 1.56 m high and offers a maximum velocity of around 20 m/s.Circular cylinders of diameter 50, 100, 300 mm were fixed across the 1.56 m height of the workingsection, enabling Reynolds number values in the range 8.2×10 4 to 4.9×10 5 to be examined. The flowpatterns around the bottom end of the cylinder were then visualised using the oil streak method. Aftersome refinement, this method has been found to yield extremely good information on the time-averagedsurface flow patterns. In the second wind tunnel, with a rectangular cross-section 0.53 mhigh times 0.46 m wide and offering a maximum velocity of 10 ms -1 , cylinders with a variety ofdifferent cross-sectional shapes (circular, aerofoil and lenticular) were located across the height of theworking section. Two-component PIV was then applied to study the flow behaviour, particularemphasis being placed upon the region of the flow upstream of the cylinder and close to the end-wall.The third velocity component was then calculated by applying continuity. However, noting theinaccuracies present when two-component PIV is used in vortical flows, a limited series ofmeasurements were also obtained using a three-component PIV system. The two sets of data will becompared.
机译:已经进行了实验来研究端壁边界层的行为。 壁挂式气缸数量。结合了使用油污涂抹的表面流可视化 使用两组分PIV的详细测量程序。 研究的目的之一是研究由以下因素产生的二次流量损失的可能性: 小心翼翼的短支撑杆可以使涡轮机的常见功能减至最小 选择圆柱体的横截面。这个想法最初是通过理论分析提出的 霍桑(1951),并由威廉姆斯(1970)进行了实验研究。目的是要重新检查 使用现在可用的更复杂的测量技术来解决问题。进一步的目标 调查的目的是建立一个高质量实验数据的数据库,以验证 计算流模型。 已经在两个不同的风洞中进行了实验。其中第一个具有矩形 横截面为4.68宽×1.56 m高,最大速度约为20 m / s。 在工作高度1.56 m上固定了直径为50、100、300 mm的圆柱体 部分中,可以检查8.2×10 4到4.9×10 5范围内的雷诺数值。流 然后使用油条法将圆柱体底端周围的图案可视化。后 进行了一些改进,发现该方法可以在平均时间上产生非常好的信息 表面流型。在第二个风洞中,具有矩形横截面0.53 m 高倍率0.46 m宽,最大速度为10 ms -1,圆柱体具有多种 横断面的高度分布有不同的横截面形状(圆形,翼型和双凸形)。 工作部分。然后将两成分的PIV用于研究流动行为,特别是 重点放在气缸上游且靠近端壁的流动区域上。 然后通过应用连续性来计算第三速度分量。但是,请注意 当在涡流中使用两组分PIV时会出现误差, 还使用三组分PIV系统获得了测量值。两组数据将是 比较的。

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