Haake Dennis, Rosendahl Uwe, Ohlhoff Antje, Dreyer Michael E
ZARM-Center of Applied Space Technology and Microgravity, University of Bremen, Bremen, Germany.
Ann N Y Acad Sci. 2006 Sep;1077:443-58. doi: 10.1196/annals.1362.031.
This paper reports the experimental and theoretical investigations of forced liquid flows through open capillary channels under reduced gravity conditions. An open capillary channel is a structure that establishes a liquid flow path at low Bond numbers, when the capillary pressure caused by the surface tension force dominates in comparison to the hydrostatic pressure induced by gravitational or residual accelerations. In case of steady flow through the channel, the capillary pressure of the free surface balances the pressure difference between the liquid and the surrounding constant-pressure gas phase. Because of convective and viscous momentum transport, the pressure along the flow path decreases and causes the free surface to bend inward. The maximum flow rate is achieved when the free surface collapses and gas ingestion occurs at the outlet. This critical flow rate depends on the geometry of the channel and the properties of the liquid. In this paper we present a comparison of the theoretical and experimental critical flow rates and surface profiles for convective dominated flows. For the prediction of the critical flow rate a one-dimensional theoretical model taking into account the entrance pressure loss and the frictional pressure loss in the channel is developed.
本文报道了在微重力条件下强迫液体流经开放式毛细管通道的实验和理论研究。开放式毛细管通道是一种在低邦德数时建立液体流动路径的结构，此时由表面张力引起的毛细管压力相较于由重力或残余加速度引起的静水压力占主导地位。在液体稳定流经通道的情况下，自由表面的毛细管压力平衡了液体与周围恒压气相之间的压力差。由于对流和粘性动量传输，沿流动路径的压力降低，导致自由表面向内弯曲。当自由表面坍塌且出口处发生气体吸入时，达到最大流速。该临界流速取决于通道的几何形状和液体的性质。在本文中，我们对对流主导流动的理论和实验临界流速及表面轮廓进行了比较。为了预测临界流速，开发了一个考虑通道入口压力损失和摩擦压力损失的一维理论模型。
