Characterization of surface roughness effects on pressure drop in single-phase flow in minichannels
Characterization of surface roughness effects on pressure drop in single-phase flow in minichannels
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DOI：
10.1063/1.1896985
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发表时间：
2005-10-01
影响因子：
4.6
通讯作者：
Taylor, JB
中科院分区：
文献类型：
--
作者：
Kandlikar, SG;Schmitt, D;Taylor, JB
通道壁的壁上的粗糙度特征影响流过该通道的流体的压降。这种粗糙度效应可以通过（i）流动面积收缩和（ii）壁面剪切应力的增加来描述。重新绘制具有收缩流动直径的穆迪摩擦系数图，可得到简化图，并在充分发展的紊流区中，对于相对粗糙度值λ/D > 0.03，可得到摩擦系数的单一渐近值。在回顾文献之后，提出了三个新的粗糙度参数（最大轮廓峰高R-p、轮廓不规则性的平均间距R-Sm和到平均线的地板距离F-p）。三个额外的参数，考虑本地化的水力直径变化（最大值，最小值和平均值）在未来的工作。然后将粗糙度定义为R-p+F-p。这个定义产生的粗糙度值与从沙粒粗糙度[H.达西，Recherches Experimentales Relatives Au Mouvement de L 'E Au dans les Tuyaux（Mallet-Bachelier，巴黎，法国，1857）; J. T. Fanning，A Practical Questiontise on Hydraulic and Water Supply Engineering（货车Nostrand，纽约，1877年，修订版1886）; J. Nikuradse，“Laws of flow in rough pipes”[“Stromungsgesetze in Rauen Rohren，”VDI-Forschungsheft 361（1933）]; Beilage zu“Forschung auf dem Gebiete des Ingenieurwesens，”Ausgabe B Band 4，English translation NACA Tech. 1292（1937）]。使用垂直于流动方向放置的平行脊形元件，在具有可变间隙的10.03 mm宽的矩形通道中以对齐和偏移配置进行特定实验（得到的水力直径为325 μ m-1819 μ m，雷诺数范围对于空气为200至7200，对于水为200至5700）。收缩流直径的使用将层流摩擦系数方程的适用性扩展到相对粗糙度值（高度）高达14%。在湍流区，对齐和偏移粗糙度安排产生不同的结果，表明需要进一步表征的表面特征。层流到湍流的转变也被认为是发生在较低的雷诺数与相对粗糙度的增加。(c)2005年美国物理学会。
Roughness features on the walls of a channel wall affect the pressure drop of a fluid flowing through that channel. This roughness effect can be described by (i) flow area constriction and (ii) increase in the wall shear stress. Replotting the Moody's friction factor chart with the constricted flow diameter results in a simplified plot and yields a single asymptotic value of friction factor for relative roughness values of epsilon/D > 0.03 in the fully developed turbulent region. After reviewing the literature, three new roughness parameters are proposed (maximum profile peak height R-p, mean spacing of profile irregularities R-Sm, and floor distance to mean line F-p). Three additional parameters are presented to consider the localized hydraulic diameter variation (maximum, minimum, and average) in future work. The roughness epsilon is then defined as R-p+F-p. This definition yields the same value of roughness as obtained from the sand-grain roughness [H. Darcy, Recherches Experimentales Relatives au Mouvement de L'Eau dans les Tuyaux (Mallet-Bachelier, Paris, France, 1857); J. T. Fanning, A Practical Treatise on Hydraulic and Water Supply Engineering (Van Nostrand, New York, 1877, revised ed. 1886); J. Nikuradse, "Laws of flow in rough pipes" ["Stromungsgesetze in Rauen Rohren," VDI-Forschungsheft 361 (1933)]; Beilage zu "Forschung auf dem Gebiete des Ingenieurwesens," Ausgabe B Band 4, English translation NACA Tech. Mem. 1292 (1937)]. Specific experiments are conducted using parallel sawtooth ridge elements, placed normal to the flow direction, in aligned and offset configurations in a 10.03 mm wide rectangular channel with variable gap (resulting hydraulic diameters of 325 mu m-1819 mu m with Reynolds numbers ranging from 200 to 7200 for air and 200 to 5700 for water). The use of constricted flow diameter extends the applicability of the laminar friction factor equations to relative roughness values (sawtooth height) up to 14%. In the turbulent region, the aligned and offset roughness arrangements yield different results indicating a need to further characterize the surface features. The laminar to turbulent transition is also seen to occur at lower Reynolds numbers with an increase in the relative roughness. (c) 2005 American Institute of Physics.