Experiments on Liquid Flow through Non-Circular Micro-Orifices

Abstract

Microfluidics is an active research area in modern fluid mechanics, with several applications in science and engineering. Despite their importance in microfluidic systems, micro-orifices with non-circular cross-sections have not been extensively investigated. In this study, micro-orifice discharge with single-phase liquid flow was experimentally investigated for seven square and rectangular cross-section micro-orifices with a hydraulic diameter in the range of 326–510 µm. The discharge measurements were carried out in pressurized water (12 MPa) at ambient temperature (298 K) and high temperature (503 K). During the tests, the Reynolds number varied between 5883 and 212,030, significantly extending the range in which data are currently available in the literature on non-circular micro-orifices. The results indicate that the cross-sectional shape of the micro-orifice has little, if any, effect on the hydrodynamic behavior. Thus, existing methods for the prediction of turbulent flow behavior in circular micro-orifices can be used to predict the flow behavior in non-circular micro-orifices, provided that the flow geometry of the non-circular micro-orifice is described using a hydraulic diameter.

Microstructural Characterization of the Corrosion Product Deposit in the Flow-Accelerated Region in High-Temperature Water

“…When the solution flows into flow cell I, the flow acceleration area forms in it, resulting in the rapid increase of streaming current, and then the transfer of wall current generated from the 304 SS to the metal/solution interface [15,16,22,30]. In the meantime, the "Karman vortex street" phenomenon will occur in the flow accelerated region, making the pressure difference between the micro-orifice on both sides increase, and causing a new current loop to promote particle deposition [19,[31][32][33][34]. According to previous calculations, the current was the highest at the edge of the flow accelerated region.…”