The Sensitivity of Counterweighted Swing Check Valve Performance to Counterweight Location

2003 ◽  
Author(s):  
L. I. Ezekoye
Keyword(s):  
Flow Resistance ◽  
Reverse Flow ◽  
Check Valve ◽  
Fast Response ◽  
Water Hammer ◽  
Flow Reversal ◽  
Reverse Direction ◽  
Valve Closure ◽  
Forward Flow ◽  
Opening And Closing

Check valves are used to minimize flow reversal. In general, the two primary design objectives of installing a check valve in a system include quick opening in forward flow and fast closure in reverse flow. The fast response requirements in both opening and closing directions are challenging. In the opening direction, the concern is to minimize forward flow resistance and, in the reverse direction, the objective is to minimize flow reversal and avoid water hammer. Check valve manufacturers have often used counterweights to permit quick opening or quick closing. The drawback of forward flow counterweight check valves is that in the flow reverse direction, the counterweights may retard valve closure. The location of the counterweight could further complicate the performance of the check valve. Misaligning the counterweight can also affect check valve performance. The use of quick closing counterweights present similar challenges. This paper examines the interaction of counterweight location and alignment on the performance of check valves.

scholarly journals Brain-wide mapping of water flow perception in zebrafish

2020 ◽  
Author(s):  
Gilles Vanwalleghem ◽  
Kevin Schuster ◽  
Michael A. Taylor ◽  
Itia A. Favre-Bulle ◽  
Ethan K. Scott
Keyword(s):  
Water Flow ◽  
Lateral Line ◽  
Reverse Flow ◽  
Forward Direction ◽  
Brain Regions ◽  
Reverse Direction ◽  
Departure Point ◽  
Forward Flow ◽  
Larval Zebrafish ◽  
The Brain

AbstractInformation about water flow, detected by lateral line organs, is critical to the behavior and survival of fish and amphibians. While certain specific aspects of water flow processing have been revealed through electrophysiology, we lack a comprehensive description of the neurons that respond to water flow and the network that they form. Here, we use brain-wide calcium imaging in combination with microfluidic stimulation to map out, at cellular resolution, all neurons involved in perceiving and processing water flow information in larval zebrafish. We find a diverse array of neurons responding to forward flow, reverse flow, or both. Early in this pathway, in the lateral line ganglia, these are almost exclusively neurons responding to the simple presence of forward or reverse flow, but later processing includes neurons responding specifically to flow onset, representing the accumulated volume of flow during a stimulus, or encoding the speed of the flow. The neurons reporting on these more nuanced details are located across numerous brain regions, including some not previously implicated in water flow processing. A graph theory-based analysis of the brain-wide water flow network shows that a majority of this processing is dedicated to forward flow detection, and this is reinforced by our finding that details like flow velocity and the total volume of accumulated flow are only encoded for the simulated forward direction. The results represent the first brain-wide description of processing for this important modality, and provide a departure point for more detailed studies of the flow of information through this network.Significance statementIn aquatic animals, the lateral line is important for detecting water flow stimuli, but the brain networks that interpret this information remain mysterious. Here, we have imaged the activity of individual neurons across the entire brains of larval zebrafish, revealing all response types and their brain locations as water flow processing occurs. We find some neurons that respond to the simple presence of water flow, and others that are attuned to the flow’s direction, speed, duration, or the accumulated volume of water that has passed during the stimulus. With this information, we modeled the underlying network, describing a system that is nuanced in its processing of water flow simulating forward motion but rudimentary in processing flow in the reverse direction.

scholarly journals Modelling foam improved oil recovery: towards a formulation of pressure-driven growth with flow reversal

2020 ◽  
Vol 476 (2244) ◽  
pp. 20200573
Author(s):  
M. Eneotu ◽  
P. Grassia
Keyword(s):  
Pressure Drop ◽  
Oil Recovery ◽  
Reverse Flow ◽  
Flow Direction ◽  
Flow Reversal ◽  
Flow Mode ◽  
Fractional Flow ◽  
Improved Oil Recovery ◽  
Forward Flow ◽  
Pressure Driven

The pressure-driven growth model that describes the two-dimensional (2-D) propagation of a foam through an oil reservoir is considered as a model for surfactant-alternating-gas improved oil recovery. The model assumes a region of low mobility, finely textured foam at the foam front where injected gas meets liquid. The net pressure driving the foam is assumed to reduce suddenly at a specific time. Parts of the foam front, deep down near the bottom of the front, must then backtrack, reversing their flow direction. Equations for one-dimensional fractional flow, underlying 2-D pressure-driven growth, are solved via the method of characteristics. In a diagram of position versus time, the backtracking front has a complex double fan structure, with two distinct characteristic fans interacting. One of these characteristic fans is a reflection of a fan already present in forward flow mode. The second fan however only appears upon flow reversal. Both fans contribute to the flow’s Darcy pressure drop, the balance of the pressure drop shifting over time from the first fan to the second. The implications for 2-D pressure-driven growth are that the foam front has even lower mobility in reverse flow mode than it had in the original forward flow case.

Topology Optimization of Fixed-Geometry Fluid Diodes

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Sen Lin ◽  
Longyu Zhao ◽  
James K. Guest ◽  
Timothy P. Weihs ◽  
Zhenyu Liu
Keyword(s):  
Topology Optimization ◽  
Reverse Flow ◽  
Flow Behavior ◽  
Projection Methods ◽  
Reverse Direction ◽  
Minimum Length ◽  
Penalty Term ◽  
Forward Flow ◽  
Dependent Flow ◽  
Minimum Length Scale

This paper proposes using topology optimization to design fixed-geometry fluid diodes that allow easy passage of fluid flowing in one direction while inhibiting flow in the reverse direction. Fixed-geometry diodes do not use movable mechanical parts or deformations, but rather utilize inertial forces of the fluid to achieve this flow behavior. Diode performance is measured by diodicity, defined as the ratio of pressure drop of reverse flow and forward flow, or equivalently the ratio of dissipation of reverse and forward flow. Diodicity can then be maximized by minimizing forward dissipation while maximizing reverse dissipation. While significant research has been conducted in topology optimization of fluids for minimizing dissipation, maximizing dissipation introduces challenges in the form of small, mesh dependent flow channels and that artificial flow in solid region becomes (numerically) desirable. These challenges are circumvented herein using projection methods for controlling the minimum length scale of channels and by introducing an additional penalty term on flow through intermediate porosities. Several solutions are presented, one of which is fabricated by 3D printing and experimentally tested to demonstrate the diodelike behavior.

Three-Dimensional FEM Simulation of a Microfluidic Diode Considering Coupled Fluid-Structure Interaction

2006 ◽  
Author(s):  
Bozhi Yang ◽  
Qiao Lin
Keyword(s):  
Flow Resistance ◽  
Reverse Flow ◽  
Fluid Structure Interaction ◽  
Applied Pressure ◽  
Three Dimensional ◽  
Fem Simulation ◽  
Fluid Structure ◽  
Forward Flow ◽  
Structure Interaction ◽  
Nonlinear Relation

This paper presents fluid-structure interaction (FSI) simulation of a microfluidic diode, which features a thin flexible flap and a rigid stopper embedded closely inside a microchannel. The thin flap deforms under different applied pressure, leading to a small flow resistance for forward flow and a large flow resistance for reverse flow. Three-dimensional simulations of structure deflection and CFD were interactively carried out to calculate the flap deformation and flow filed using ANSYS® Multi-field™ solver. In the simulations nonlinear hyperelastic material property was used for the thin flap, and the pressure drop across device inlet and outlet was applied in small increments to solve the nonlinear continuum mechanics problems. The simulated flap deflections under both forward and reverse flow show nonlinear relation between deflection and pressure, consistent with experimental data. The simulated flow rates under various pressures also agree well with the measurement results, within 15% error for forward flow and 17% for reverse flow. The simulations can be used as guidelines for optimal design of the microfluidic diode.

An Experimental Study to Predict Dynamic Performance of Check Valve by Water Hammer

2019 ◽  
Vol 19 (1) ◽  
pp. 1-12
Author(s):  
Tae-Kook Park ◽  
Yong-Bum Lee ◽  
Jae-Hyeong Kim ◽  
Ki-Chun Lee ◽  
Dong-Cheon Baek
Keyword(s):  
Experimental Study ◽  
Dynamic Performance ◽  
Check Valve ◽  
Water Hammer

Blood Velocity Patterns in Poststenotic Regions and Velocity Waveforms for Myocardial Inflow Associated With Coronary Artery Stenosis in Dogs

1992 ◽  
Vol 114 (3) ◽  
pp. 385-390 ◽  
Author(s):  
F. Kajiya ◽  
O. Hiramatsu ◽  
A. Kimura ◽  
T. Yamamoto ◽  
T. Yada ◽  
...  
Keyword(s):  
Coronary Artery ◽  
Left Coronary Artery ◽  
Coronary Artery Stenosis ◽  
Reverse Flow ◽  
Blood Velocity ◽  
Small Artery ◽  
Forward Flow ◽  
Velocity Waveform ◽  
Narrow Region ◽  
Remarkable Reduction

Velocity profiles across a vessel were investigated in poststenotic regions of the canine left coronary artery by our 80-channel 20 MHz ultrasound velocimeter. The velocity waveform in a small artery just before its penetration into myocardium was measured by our laser Doppler method. The poststenotic velocity configuration was characterized by a narrow region of high velocity with diastolic reverse flow near the wall which may dissipate energy. The velocity waveform in the distal small arteries exhibited increased systolic reverse flow with decreased diastolic forward flow, resulting in a remarkable reduction of coronary inflow into the myocardium.

Abstract 12430: Vicious Circle Between Progressive Right Ventricular Dilatation and Pulmonary Regurgitation in Patients After Tetralogy of Fallot Repair? Right Heart Enlargement Promotes Flow Reversal in the Left Pulmonary Artery

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Atsuko Kato ◽  
Christian Drolet ◽  
Shi-Joon Yoo ◽  
Andrew Redington ◽  
Lars Grosse-Wortmann
Keyword(s):  
Pulmonary Artery ◽  
Tetralogy Of Fallot ◽  
Left Lung ◽  
Pulmonary Regurgitation ◽  
Left Pulmonary Artery ◽  
Flow Reversal ◽  
Left Hemithorax ◽  
Forward Flow ◽  
Lung Area ◽  
The Right

Introduction: The left pulmonary artery (LPA) contributes more than the right (RPA) to total pulmonary regurgitation (PR) in patients after tetralogy of Fallot (TOF) repair, but the mechanism of this difference is not well known. We hypothesized that unilaterally increased pulmonary vascular resistance (PVR), resulting from lung compression by the enlarged and levorotated heart leads to greater PR in the LPA. This study aimed to analyze the interplay between heart and lung size, mediastinal geometry, and differential PR. Methods: This is a single-center retrospective analysis of 50 magnetic resonance studies in patients after TOF repair. Patients with more than mild discrete branch pulmonary artery stenosis were excluded. Blood flow was measured by phase-contrast velocity encoding within the branch pulmonary arteries. On the axial image with the largest total cardiac surface area, cardiac angle (α) between the thoracic anterior-posterior line and the interventricular septum, right and left lung areas as well as right and left hemithorax areas were measured (Figure). Results: There was no difference in LPA and RPA diameters. The LPA showed significantly less total forward flow (p=0.04), smaller net forward flow (p=<0.001), and greater RF (p=0.001) than the RPA. Left lung area was smaller than the right (p<0.001). RVEDVi correlated with LPA RF (R=0.48, p<0.001), but not with RPA RF. Larger RVEDVi correlated with a larger α angle (R=0.46, p<0.001), i.e. a more leftward cardiac axis and with smaller left lung area (R=-0.58, p<0.001). LPA RF, but not RPA RF, correlated inversely with left lung area indexed to the left hemithorax area (R=-0.34, p=0.02). Conclusions: An enlarged and levorotated heart - as a result of PR - is associated with smaller left lung size, and augments diastolic flow reversal in the LPA, presumably via increased left PVR. By imposing a further volume load on the RV, LPA regurgitation may thus close a positive feed-back loop of PR and RV dilatation.

Effects of Valve Disc on Flow Characteristics Inside a Swing Check Valve During Opening and Closing Processes

2021 ◽  
Author(s):  
Yi-xiang Xu ◽  
Qiang Ru ◽  
Huai-yu Yao ◽  
Zhi-jiang Jin ◽  
Jin-yuan Qian
Keyword(s):  
Flow Field ◽  
Working Conditions ◽  
Power Plants ◽  
Flow Characteristics ◽  
Check Valve ◽  
Opening Angle ◽  
Piping System ◽  
Total Moment ◽  
Valve Disc ◽  
Opening And Closing

Abstract The check valve is one of the most important devices for safety protection of the piping system in thermal and nuclear power plants. As the key component of the check valve, the valve disc accounts for a major effect on the flow characteristics especially during the opening and closing processes. In this paper, a typical swing check valve is taken as the research object. In order to make a comparative study, three working conditions of 30% THA (Turbine Heat Acceptance), 50% THA and 100% THA are selected. Focusing on the effects of valve disc, how does the valve disc motion interact with the flow field around the valve disc is analyzed with the help of the dynamic mesh technology. The results show that under the combined action of fluid force and gravity, the check valve can be opened and closed quickly. During the opening process, the maximum total moment of the disc appears between 45° ∼ 50° opening angle, and during the closing process the maximum total moment occurs when the disc fully closed. The flow field near the valve disc has similar variation rules with the rotation of the valve disc in the three working conditions, and the pressure near the valve disc reaches the maximum value at the moment of opening and closing. This study can provide some suggestions for the further optimal design of similar swing check valve.

The Theoretical Volumetric Displacement of a Check-Valve Type, Digital Displacement Pump

2018 ◽  
Vol 141 (3) ◽  
Author(s):  
Noah Manring ◽  
Christopher Williamson
Keyword(s):  
Bulk Modulus ◽  
Flow Rate ◽  
Modulus Of Elasticity ◽  
Check Valve ◽  
Volumetric Flow Rate ◽  
Theoretical Explanation ◽  
Residual Volume ◽  
Displacement Pump ◽  
Opening And Closing ◽  
Piston Chamber

This paper has been written to develop closed-form equations for describing the theoretical displacement of a check-valve type, digital displacement pump. In theory, the digital displacement pump is used to alter the apparent volumetric displacement of the machine by short circuiting the flow path for reciprocating pistons within the machine that would ordinarily deliver a full volumetric flow rate to the discharge side of the pump. The short circuiting for the pistons is achieved by opening and closing a digital valve connected to each piston chamber at a desired time during the kinematic cycle for each reciprocating piston. Experience with these machines has shown that the expected volumetric displacement for the machine tends to decrease with pressure. This paper presents a theoretical explanation for the reduced volumetric displacement of the pump and quantifies the expected behavior based upon the digital valve command, the residual volume of fluid within a single piston chamber, and the fluid bulk modulus-of-elasticity. In summary, it shown that the apparent volumetric displacement of the machine may be reduced by as much as 10% for high-displacement commands and by as much as 30% for low-displacement commands.

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