Micropumps are microfluidic components which are widely used in applications such as chemical analysis, biological sensing and micro-robots. However, one obstacle in developing micropumps is the extremely low efficiency relative to their macro-scale counterparts. This paper presents a dynamic sealing method for external gear pumps to reduce the volumetric losses through the clearance between the tips of gears and the housing by using magneto-rheological (MR) fluids. By mitigating these losses, we are able to achieve high efficiency and high volumetric accuracy with current mechanical architectures and manufacturing tolerances. Static and dynamic sealing using MR fluids are investigated theoretically and experimentally. Two Mason numbers M n (p) and M n (Ω) which are defined in terms of pressure gradient of the flow and velocity of the moving boundary respectively are used to characterize and evaluate the sealing performance. A range of magnetic field intensities is explored to determine optimal sealing effectiveness, where effectiveness is evaluated using the ratio of volumetric loss and friction factor. Finally, we quantify the effectiveness of this dynamic sealing method under different working conditions for gear pumps.
Metasurfaces open up unprecedented potential for applications in acoustic deflection. Achieving adaptive control of a scattered sound field (SSF) using a flexible metasurface structure is of great scientific interest. However, as the conventional finite element method (FEM) is limited by computational efficiency, it is necessary to develop a fast and accurate method to predict the SSF. In this work, we design a chessboard device with an array of square grooves for the modulation of SSF and develop a fast calculation method for 3D SSF using a Kirchhoff approximation phase correction. Several SSF spatial modulations obtained using the chessboard model are computed with a fast algorithm. In addition, an experimental test-case in a semi-anechoic chamber, contrasted and analyzed scattered acoustic pressure using FEM, is designed to regulate the SSF performance of the chessboard device. Field measurements obtained show that the spatial directivity of chessboard device can be modified by artificially programming the phase or depth distribution of the groove array. The chessboard device and associated fast calculation method lend themselves to applications in the acoustic stealth of targets in air or water.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.