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Lemétayer J, Broman LM, Prahl Wittberg L. Confined jets in co-flow: effect of the flow rate ratio and lateral position of a return cannula on the flow dynamics. SN APPLIED SCIENCES 2020. [DOI: 10.1007/s42452-020-2077-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
AbstractCo-axial tubes have been used to produce a co-flowing confined jet similar to that found in an Extracorporeal Membrane Oxygenation return cannula flow configuration. Particle Image Velocimetry was used to investigate the flow rate ratio between jet and co-flow as well as changes in flow characteristics due to cannula position. The flow was found to be dominated by three main structures: lateral flow entrainment, shear layer induced vortices and backflow along the wall. An increase in cannula flow rate amplified entrainment and recirculation, resulting in a decrease in length required to reach a fully developed flow. Changing cannula position relative the outer cylinder induced a significant reduction in recirculation zone as well as vortex formation on the side to which the cannula was tilted towards, whereas on the other side, the recirculating flow region was enhanced. Proper Orthogonal Decomposition demonstrated that the dominating structure found in the flow is the backflow, composing of several structures having different oscillation frequencies. The significance of the observed and measured flow structures is in enhancing mixing.
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Abstract
One of the main advantages of fluidic oscillators is that they do not have moving parts, which brings high reliability whenever being used in real applications. To use these devices in real applications, it is necessary to evaluate their performance, since each application requires a particular injected fluid momentum and frequency. In this paper, the performance of a given fluidic oscillator is evaluated at different Reynolds numbers via a 3D-computational fluid dynamics (CFD) analysis. The net momentum applied to the incoming jet is compared with the dynamic maximum stagnation pressure in the mixing chamber, to the dynamic output mass flow, to the dynamic feedback channels mass flow, to the pressure acting to both feedback channels outlets, and to the mixing chamber inlet jet oscillation angle. A perfect correlation between these parameters is obtained, therefore indicating the oscillation is triggered by the pressure momentum term applied to the jet at the feedback channels outlets. The paper proves that the stagnation pressure fluctuations appearing at the mixing chamber inclined walls are responsible for the pressure momentum term acting at the feedback channels outlets. Until now it was thought that the oscillations were driven by the mass flow flowing along the feedback channels, however in this paper it is proved that the oscillations are pressure driven. The peak to peak stagnation pressure fluctuations increase with increasing Reynolds number, and so does the pressure momentum term acting onto the mixing chamber inlet incoming jet.
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Performance Analysis of a Fluidic Axial Oscillation Tool for Friction Reduction with the Absence of a Throttling Plate. APPLIED SCIENCES-BASEL 2017. [DOI: 10.3390/app7040360] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Performance Study of a Fluidic Hammer Controlled by an Output-Fed Bistable Fluidic Oscillator. APPLIED SCIENCES-BASEL 2016. [DOI: 10.3390/app6100305] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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High-speed rainbow schlieren visualization of an oscillating helium jet undergoing gravitational change. J Vis (Tokyo) 2006. [DOI: 10.1007/bf03181573] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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