Abstract
The flow characteristics of the single-phase liquid and the gas–liquid two-phase flows including the Newtonian and non-Newtonian liquids were experimentally investigated in a horizontal rectangular micro-channel with a sudden contraction—specifically the pressure change across the contraction. The rectangular cross-sectional dimension has Wu × Hu (width × height) = 0.99 × 0.50 mm2 on the upstream side of the contraction and Wd × Hd = 0.49 × 0.50 mm2 on the downstream side. The resulting contraction ratio, σA (=Wd/Wu), was 0.5. Air was used as the test gas (in the case of the gas–liquid two-phase flow experiment), distilled water and three kinds of aqueous solution, i.e., glycerin 25 wt%, xanthangum 0.1 wt% and polyacrylamide 0.11 wt% were used as the test liquid. The pressure distribution in the flow direction upstream and downstream of the channel was measured. The pressure change and loss at the sudden contraction were determined from the pressure distribution. In addition, the pressure change data were compared with the calculation by several correlations proposed by various researchers as well as a newly developed correlation in this study. From the comparisons, it was found that calculations by the newly developed correlations agreed well with the measured values within the error of 30%.
Highlights
IntroductionThermo-fluid devices and blood circulatory systems contain flow channels of various cross-sections, e.g., circular and rectangular, as well as various types of geometrical singularities, such as abrupt flow area changes (sudden contractions, sudden expansions and bends, branches, etc.)
This study experimentally investigated the pressure change for the single- and twoThis studyphase experimentally the pressure change for the single-sudden and twoNewtonianinvestigated and non-Newtonian viscous flows through contraction in a phase Newtonian and non-Newtonian viscous flows through sudden contraction in a horhorizontal rectangular microchannel
Regardless of the test liquid, the sudden contraction pressure drop, ∆PCI,L, for singlephase liquid flows increased as the average flow velocity increased
Summary
Thermo-fluid devices and blood circulatory systems contain flow channels of various cross-sections, e.g., circular and rectangular, as well as various types of geometrical singularities, such as abrupt flow area changes (sudden contractions, sudden expansions and bends, branches, etc.). With the progress of advanced micromachining technology, devices have been miniaturized and the use of micro-devices has become widespread, e.g., micro-reactors [2], mobile-type fuel cell [3], and micro-heat exchangers [4]. It is essential for the development and the design of the micro-devices to know the characteristics of the single-phase flow and the two-phase flow across the singularities [5,6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
