Flow regime characterisation of an impinging axisymmetric synthetic jet
Flow regime characterisation of an impinging axisymmetric synthetic jet
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DOI：
10.1016/j.expthermflusci.2013.02.003
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发表时间：
2013-05
影响因子：
3.2
通讯作者：
Alan McGuinn;R. Farrelly;T. Persoons;D. Murray
中科院分区：
文献类型：
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作者：
Alan McGuinn;R. Farrelly;T. Persoons;D. Murray
撞击合成射流在受限几何形状的局部节能降温方面具有极好的潜力。对于给定的几何形状，合成射流的主要特征是雷诺数和冲程长度与几何长度尺度的比率。冲击合成射流的流场和相应的表面换热分布强烈地依赖于无因次冲程长度，但很少有研究在较大的冲程长度范围内研究流场的相关性。因此，本文的目的是确定不同的流型作为冲程长度的函数。该实验方法结合了高速粒子图像测速技术和单点热线测速技术，在较宽的冲程长度(3<；L0/D<；32)和喷嘴与表面的间距(2<；H/D<；16)范围内，研究了轴对称合成空气射流撞击光滑平面的情况。由于对雷诺数效应有更好的理解，大多数结果是针对单个雷诺数的(Re=1500)。基于冲程长度L0/D的阈值，确定了四种自由合成射流形态，这与以前发表的脉冲启动射流的结果很好地一致。此外，基于归一化行程长度与喷嘴表面间距之比(L0−2D)/H的阈值，确定了四种冲击合成射流流型，这与先前公布的驻点换热区域的阈值很好地一致。
Impinging synthetic jets have excellent potential for energy-efficient local cooling in confined geometries. For a given geometry, synthetic jet flows are mainly characterised by the Reynolds number and the ratio of stroke length to a geometric length scale. The flow field of an impinging synthetic jet and the corresponding surface heat transfer distribution are strongly dependent on the dimensionless stroke length, yet few studies have investigated the flow field dependence for a wide range of stroke lengths. Therefore, the aim of this paper is to identify the various flow regimes as a function of stroke length. The experimental approach combines high speed particle image velocimetry and single point hot wire anemometry, and investigates an axisymmetric synthetic air jet impinging onto a smooth planar surface for a wide range of stroke length (3<L0/D<32) and nozzle-to-surface spacing (2<H/D<16). Since the Reynolds number effect is better understood, most of the presented results are for a single Reynolds number (Re=1500). Four free synthetic jet flow morphology regimes are identified based on threshold values for the stroke length L0/D, which are in good agreement with previously published findings for an impulsively started jet flow. Furthermore, four impinging synthetic jet flow regimes are identified based on threshold values for the ratio of normalised stroke length to nozzle-to-surface spacing (L0−2D)/H, which are in good agreement with previously published thresholds for stagnation point heat transfer regimes.