高宽比对矩形窄通道内单相水流动特性的影响机理

通过理论和实验研究了矩形窄通道内单相水的流动特性。结果表明：矩形通道截面高宽比对其流动阻力有重要影响，层流区和紊流光滑管区摩擦阻力均随高宽比的减小而增大。可视化结果表明：矩形窄通道临界Re为2 500~2 600，高宽比对窄通道内流态转捩无明显影响。层流区高宽比通过改变截面湿周及速度分布两方面影响摩阻特性；紊流区高宽比通过改变黏性底层紊流时均速度分布及截面湿周两方面影响摩阻特性。

Mechanism of Effect of Aspect Ratios on Single-Phase Water Flow Behaviors in Narrow Rectangular Ducts

Single-phase water flow behaviors in narrow rectangular ducts were studied theoretically and experimentally. The results show that aspect ratios have significant influence on flow resistance. The frictional resistance in rectangular duct increases as the aspect ratio decreases both in laminar flow region and the smooth region of turbulent flow. The visual observation shows that critical Reynolds number for narrow rectangular ducts ranges from 2 500 to 2 600, and the aspect ratio nearly has insignificant influence on flow regime transition. The single-phase flow resistance is influenced significantly by wetting perimeter and velocity distribution, which vary with the aspect ratio in laminar flow. For turbulent flow, the turbulent mean velocity in viscous sub-layer and wetting parameter become important parameters affecting the flow resistance.