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Flow Rate Limitation in Open Capillary Channel Flows
Author(s) -
HAAKE DENNIS,
ROSENDAHL UWE,
OHLHOFF ANTJE,
DREYER MICHAEL E.
Publication year - 2006
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1196/annals.1362.031
Subject(s) - open channel flow , mechanics , capillary action , surface tension , volumetric flow rate , hydrostatic pressure , flow (mathematics) , free surface , chemistry , capillary pressure , isothermal flow , pressure drop , flow coefficient , pressure gradient , two phase flow , energy–depth relationship in a rectangular channel , thermodynamics , physics , organic chemistry , porous medium , porosity , chézy formula
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.