Incipience of Liquid Entrainment From a Stratified Gas-Liquid Region in Multiple Discharging Branches

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
R. C. Bowden ◽  
I. G. Hassan
Keyword(s):  
Industrial Applications ◽  
Liquid Interface ◽  
Liquid Level ◽  
Analytical Models ◽  
Liquid Region ◽  
Critical Height ◽  
Two Phase ◽  
Curvature Effects ◽  
Liquid Entrainment ◽  
Flow Quality

The onset of liquid entrainment in discharging branches, from a stratified gas-liquid region, has implications in industrial applications where safety is of concern. The onset criterion was characterized by the critical height, the vertical distance from the discharge inlet to the gas-liquid interface, and was shown to be a function of the Froude number. The critical height signified a transition in the discharging flow quality from a single phase gas to a two-phase gas-liquid mixture. The onset of liquid entrainment with multiple discharging branches, and a stratified gas-liquid region, was experimentally investigated using air and water. A test section with a semicircular cross section and three discharging branches at 0deg, 45deg, and 90deg was used. The critical height was recorded using both increasing and decreasing liquid level methods, thereby demonstrating surface tension and wetness effects. A total of eight cases were investigated for single, dual, and triple discharges, with onset occurring in the branch closest to and above the gas-liquid interface. Wall curvature effects were discussed through comparison with previous flat wall studies. Agreement between previously developed analytical models and the decreasing liquid level results was found.

scholarly journals Investigation of Zero Moment Point in a Partially Filled Liquid Vessel Subjected to Roll Motion

2020 ◽  
Vol 10 (11) ◽  
pp. 3992
Author(s):  
Muhammad Usman ◽  
Muhammad Sajid ◽  
Emad Uddin ◽  
Yasar Ayaz
Keyword(s):  
Autonomous Vehicles ◽  
Center Of Mass ◽  
Flow Analysis ◽  
Liquid Interface ◽  
Liquid Region ◽  
Time Step ◽  
Two Phase ◽  
Zero Moment Point ◽  
Zero Moment ◽  
Air Liquid Interface

Liquid-handling robots are designed to dispense sub-microliter quantities of fluids for applications including laboratory tests. When larger amounts of liquids are involved, sloshing must be considered as a parameter affecting stability, which is of significance for autonomous vehicles. The measurement and quantification of slosh in enclosed volumes poses a challenge to researchers who have traditionally resorted to tracking the air–liquid interface for two-phase flow analysis. There is a need for a simpler method to predict rollover in these applications. In this work, a novel solution to address this problem is proposed in the form of the Zero Moment Point (ZMP) of a dynamic liquid region. Computational experiments of a partially filled, two-dimensional liquid vessel were carried out using the Volume of Fluid (VOF) method in a finite volume based open-source computational fluid dynamics solver. The movement of the air–liquid interface was tracked, while the Center of Mass and the resulting Zero Moment Point were determined from the numerical simulations at each time step. The computational model was validated by comparing the wall pressure and movement of the liquid-free surface to experimentally obtained values. It was concluded that for a dynamic liquid domain, the Zero Moment Point can be instrumental in determining the stability of partially filled containers subjected to sloshing.

A New Criterion for the Onset of Liquid Entrainment From a Stratified Two-Phase Region Through a Small Branch

2009 ◽  
Author(s):  
Mahmoud Ahmed ◽  
Ahmed Hamza H. Ali
Keyword(s):  
Flow Instability ◽  
Vertical Wall ◽  
Phase Region ◽  
Three Dimensional Model ◽  
Critical Height ◽  
Two Phase ◽  
Local Flow ◽  
Liquid Entrainment ◽  
Small Branch ◽  
New Criterion

A new criterion has been developed to predict the onset of liquid (heavier fluid) entrainment from a stratified two-phase region through single and dual branches mounted on a vertical wall. This criterion was based on the local instability of the interface between two fluids due to the suction effect associated with the discharging of the lighter fluid. To validate the criterion, a three-dimensional model has been developed to predict the critical height at the onset of liquid entrainment. Comparisons between the theoretical critical heights with the available experimental data demonstrated a very good concurrence between the predicted and the measured values for both single and dual branches. This indicated that the onset of liquid entrainment mechanism occurs due to local flow instability of the interface analogous to Taylor instability.

Flow Field Characterization at the Onset of Gas Entrainment in a Single Downward Discharge Using Particle Image Velocimetry

2007 ◽  
Vol 129 (12) ◽  
pp. 1565-1576 ◽  
Author(s):  
R. C. Bowden ◽  
I. G. Hassan
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Particle Image ◽  
Particle Image Velocimetry Data ◽  
Industrial Applications ◽  
Liquid Region ◽  
Two Phase ◽  
Gas Entrainment ◽  
Image Velocimetry ◽  
Side Flow

The incipience of two-phase flow in discharging branches from a stratified gas-liquid region has major implications in industrial applications where safety is of concern. An experimental investigation of the liquid side flow field at the onset of gas entrainment, in a single downward oriented discharging branch, was presented. Particle image velocimetry was used to measure the liquid side flow field in horizontal and vertical planes. Averaged velocity profiles were presented and demonstrated a highly radial flow. The particle image velocimetry data were validated using continuity and showed that the mass flow rate to be in the range of 10–25% of the expected value. Further, the vortex-free flow field assumption, used previously in the development of analytical and empirical models, was found to be reasonable.

Characterizing the Onset of Gas Entrainment in a Single Discharging Bottom Branch Through Flow Visualization

2006 ◽  
Author(s):  
R. C. Bowden ◽  
I. G. Hassan
Keyword(s):  
Flow Field ◽  
Two Phase Flow ◽  
Solid Wall ◽  
Vertical Plane ◽  
Industrial Applications ◽  
Liquid Region ◽  
Primary Concern ◽  
Phase Flow ◽  
Two Phase ◽  
Gas Entrainment

The incipience of two-phase flow in discharging branches, from a stratified gas-liquid region, has major implications in industrial applications where safety is of primary concern. The transition from single phase liquid to a two phase gas-liquid mixture is termed the onset of gas entrainment, and may be formed by either vortex or vortex-free mechanisms. The two phase flow quality in the discharging branch is greatly impacted by vortex-free gas entrainment, as compared with gas entrainment due to vortex formation. Presented is a preliminary experimental investigation to demonstrate quantitative measurements of the liquid flow field at the onset of gas entrainment in a single discharging bottom branch. The three dimensional flow field is resolved into three horizontal planes and a single vertical plane. Results indicate a strong dependency of the flow field on the radial component, directed toward the branch center, and where a solid wall is present a larger tangential component.

scholarly journals Time-resolved PIV measurements of a deflected submerged jet interacting with liquid-gas and liquid-liquid interfaces

2021 ◽  
Author(s):  
Stefan Puttinger ◽  
Mahdi Saeedipour
Keyword(s):  
Liquid Layer ◽  
Large Scale ◽  
Free Surface Flow ◽  
Industrial Applications ◽  
Liquid Pool ◽  
Surface Flow ◽  
Two Phase ◽  
Time Resolved ◽  
Submerged Jet ◽  
Major Interest

AbstractThis paper presents an experimental investigation on the interactions of a deflected submerged jet into a liquid pool with its above interface in the absence and presence of an additional lighter liquid. Whereas the former is a free surface flow, the latter mimics a situation of two stratified liquids where the liquid-liquid interface is disturbed by large-scale motions in the liquid pool. Such configurations are encountered in various industrial applications and, in most cases, it is of major interest to avoid the entrainment of droplets from the lighter liquid into the main flow. Therefore, it is important to understand the fluid dynamics in such configurations and to analyze the differences between the cases with and without the additional liquid layer. To study this problem, we applied time-resolved particle image velocimetry experiments with high spatial resolution. A detailed data analysis of a small layer beneath the interface shows that although the presence of an additional liquid layer stabilizes the oscillations of the submerged jet significantly, the amount of kinetic energy, enstrophy, and velocity fluctuations concentrated in the proximity of the interface is higher when the oil layer is present. In addition, we analyze the energy distribution across the eigenmodes of a proper orthogonal distribution and the distribution of strain and vortex dominated regions. As the main objective of this study, these high-resolution time-resolved experimental data provide a validation platform for the development of new models in the context of the volume of fluid-based large eddy simulation of turbulent two-phase flows.

scholarly journals Automated Insertion of Objects Into an Acoustic Robotic Gripper

Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 40
Author(s):  
Marc Röthlisberger ◽  
Marcel Schuck ◽  
Laurenz Kulmer ◽  
Johann W. Kolar
Keyword(s):  
Acoustic Field ◽  
Acoustic Waves ◽  
Acoustic Pressure ◽  
Pressure Field ◽  
Acoustic Power ◽  
Industrial Applications ◽  
High Density ◽  
Analytical Models ◽  
Acoustic Levitation ◽  
Mechanical Contact

Acoustic levitation forces can be used to manipulate small objects and liquid without mechanical contact or contamination. To use acoustic levitation for contactless robotic grippers, automated insertion of objects into the acoustic pressure field is necessary. This work presents analytical models based on which concepts for the controlled insertion of objects are developed. Two prototypes of acoustic grippers are implemented and used to experimentally verify the lifting of objects into the acoustic field. Using standing acoustic waves and by dynamically adjusting the acoustic power, the lifting of high-density objects (>7 g/cm3) from acoustically transparent surfaces is demonstrated. Moreover, a combination of different acoustic traps is used to lift lower-density objects from acoustically reflective surfaces. The provided results open up new possibilities for the implementation of acoustic levitation in robotic grippers, which have the potential to be used in a variety of industrial applications.

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