Experimental Characterization of Two-Phase Swirl Flow Interacting With a Circular Bluff Body

2021 ◽  
Author(s):  
Rafael Gonzalez Hernandez ◽  
Afshin Goharzadeh ◽  
Mahmoud Meribout ◽  
Lyes Khezzar
Keyword(s):  
High Speed ◽  
Bluff Body ◽  
Transition Period ◽  
Swirl Flow ◽  
Critical Distance ◽  
High Speed Photography ◽  
Flow Loop ◽  
Two Phase ◽  
Air Pocket ◽  
Air Core

Abstract This study presents an experimental investigation of two-phase swirl flow interacting with a circular bluff body. A horizontal and transparent multiphase flow loop is employed to investigate the dynamic of swirl flow close to the circular bluff body. Using high-speed photography, air-core development during the transition period is characterized. Analysis of both instantaneous and averaged images provides key information on air-core length and diameter for steady state conditions. The distance from air-core tip to the disk depends on a critical gas-liquid ratio (GLRc). The presence of air pocket behind the circular bluff body depends on a critical distance to the disk.

Experiments on Turbulent Air-Water Swirling Flow in a Pipe With a Circular Disk

2019 ◽  
Author(s):  
Zhang Tianxing ◽  
Ayesha Almheiri ◽  
Lyes Khezzar ◽  
Mohamed Alshehhi ◽  
Saqib Salam
Keyword(s):  
High Speed ◽  
Bluff Body ◽  
Swirling Flow ◽  
Liquid Velocity ◽  
Reverse Flow ◽  
Circular Disk ◽  
Internal Diameter ◽  
High Speed Photography ◽  
Two Phase ◽  
Radial Profiles

Abstract This paper presents an experimental study conducted on turbulent single and two-phase swirling flow in a circular pipe with a bluff body. Laser Doppler Velocimetry (LDV) was used to measure liquid velocity radial profiles. The measurements were performed in a closed water-air loop system with a horizontal test section of length 610 mm and 41 mm internal diameter. The measurement campaign was performed at different axial locations to document the flow field without and with the presence of an air core respectively. The measurements were conducted with water flow rates which corresponded to Reynolds numbers based on pipe diameter and average liquid velocity of 14,500 and 19,450 for single phase and liquid-gas swirling flow, respectively. Analysis of the results reveals a more noticeable reverse flow along the whole pipe intensifying rather than being dampened as expected due to the swirl decay. High-speed photography shows that at a GLR = 0.3% the gas core does not touch the bluff body but breaks down just ahead of the disk surface.

Droplet transfer behavior of narrow gap laser wire filling welding

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940045 ◽  
Author(s):  
Z. Zhang ◽  
R. Wang ◽  
G. Gou ◽  
H. Chen ◽  
W. Gao
Keyword(s):  
Welding Speed ◽  
High Speed ◽  
Transition Period ◽  
High Speed Photography ◽  
Narrow Gap ◽  
Droplet Transfer ◽  
Transfer Behavior ◽  
Feeding Speed ◽  
Wire Feeding ◽  
Droplet Transition

In this paper, we study the droplet transition behavior of narrow gap laser wire filling welding under the condition of changing welding speed and wire feeding speed, and it was observed by high-speed photography. It was found that with the increase of welding speed, the frequency of droplet transfer was reduced and the transition period was prolonged. With the increase of wire feeding speed, the wire was not fully melted and finally inserted into the molten pool.

Experimental Characterization of a Modified Airlift Pump

2014 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Keegan Fernandes
Keyword(s):  
Water Flow ◽  
Flow Rate ◽  
High Speed ◽  
Water Flow Rate ◽  
High Speed Photography ◽  
Two Phase ◽  
Inner Diameter ◽  
Airlift Pump ◽  
Flow Map ◽  
Churn Flow

This paper presents an experimental investigation on a modified airlift pump. Experiments were undertaken as a function of air-water flow rate for two submergence ratios (ε=0.58 and 0.74), and two different riser geometries (i) straight pipe with a constant inner diameter of 19 mm and (ii) enlarged pipe with a sudden expanded diameter of 19 to 32 mm. These transparent vertical pipes, of 1 m length, were submerged in a transparent rectangular tank (0.45×0.45×1.1 m3). The compressed air was injected into the vertical pipe to lift the water from the reservoir. The flow map regime is established for both configurations and compared with previous studies. The two phase air-water flow structure at the expansion region is experimentally characterized. Pipeline geometry is found to have a significant influence on the output water flow rate. Using high speed photography and electrical conductivity probes, new flow regimes, such as “slug to churn” and “annular to churn” flow, are observed and their influence on the output water flow rate and efficiency are discussed. These experimental results provide fundamental insights into the physics of modified airlift pump.

Age-Related Differences in Throwing Techniques Used by the Catcher in Baseball

1994 ◽  
Vol 6 (3) ◽  
pp. 225-235 ◽  
Author(s):  
Shinji Sakurai ◽  
Bruce Elliott ◽  
J. Robert Grove
Keyword(s):  
High Speed ◽  
High Performance ◽  
Age Groups ◽  
Three Dimensional ◽  
Transformation Method ◽  
High Speed Photography ◽  
Two Phase ◽  
Ball Speed ◽  
Age Related ◽  
Release Speed

Three-dimensional (3-D) high speed photography was used to record the overarm throwing actions of five open-age, four 18-year-old, six 16-year- old, and six 14-year-old high-performance baseball catchers. The direct linear transformation method was used for 3-D space reconstruction from 2-D images of the catchers throwing from home plate to second base recorded using two phase-locked cameras operating at a nominal rate of 200 Hz. Selected physical capacity measures were also recorded and correlated with ball release speed. In general, anthropometric and strength measures significantly increased through the 14-year-old to open-age classifications, while a range of correlation coefficients from .50 to .84 was recorded between these physical capacities and ball speed at release. While many aspects of the kinematic data at release were similar, the key factors of release angle and release speed varied for the different age groups.

Simulation of jet velocity in the melt-blowing process using the coupled air–polymer model

2018 ◽  
Vol 89 (16) ◽  
pp. 3221-3233 ◽  
Author(s):  
Xibo Hao ◽  
Hui Huang ◽  
Yongchun Zeng
Keyword(s):  
High Speed ◽  
Flow Model ◽  
Processing Parameters ◽  
High Speed Photography ◽  
Critical Factors ◽  
Polymer Model ◽  
Melt Blowing ◽  
Two Phase ◽  
Jet Velocity ◽  
Jet Velocities

The polymer jet velocity is one of the most basic and critical factors in the melt-blowing process and has always been difficult to measure online. Much effort has been made on the numerical prediction of the jet velocity. However, little work has involved the complex interaction between the air flow and the polymer. Here, the Level-Set method is used to develop the coupled air–polymer two-phase flow model, and to simulate the polymer jet motion in the melt-blowing process considering the coupled effect of the air and polymer. Meanwhile, high-speed photography is adopted in the experiments to verify the simulation results. The x- and y-components of the jet velocities and the whipping amplitude of the jet motion are discussed. The rapid increase of jet velocity and the decrease of jet diameter show that most attenuation of the polymer jet occurred within a distance close to the die (10 mm). Based on the model, the effects of the processing parameters on the jet velocity are examined numerically.

Studies of Swirl Burner Characteristics, Flame Lengths and Relative Pressure Amplitudes

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
A. Valera-Medina ◽  
N. Syred ◽  
P. Bowen ◽  
A. Crayford
Keyword(s):  
High Speed ◽  
Fossil Fuels ◽  
Fuel Injection ◽  
Flame Length ◽  
Swirl Flow ◽  
High Speed Photography ◽  
Relative Pressure ◽  
Fuel Injector ◽  
Swirl Burner ◽  
Potential Oscillations

Swirl stabilized combustion is a technology which, for stationary combustion, consumes more than 70 to 80% of the world’s fossil fuels. There have been many reviews of this technology, but there are still many gaps in understanding. This paper focuses on the general characteristics of a 100kW swirl burner, originally designed for poor quality fuels, in terms of flame characteristic, length and pressure fluctuations, to give a relative measure of the propensity of the system to respond to outside perturbations. Studied effects include swirl number, symmetry of the swirl flow system, type of fuel injector and mode of fuel injection. A range of techniques, including High Speed Photography (HSP), Particle Image Velocimetry (PIV) and fluctuating pressure measurements were used to create flame maps, flame length detail, and relative pressure amplitudes graphs. The results are discussed in the context of potential oscillations and coupling mechanisms including the effect of the precessing vortex core (PVC), recirculation and shear flow instabilities.

High-speed photography in the study of two-phase flow

1961 ◽  
Vol 39 (4) ◽  
pp. 159-164 ◽  
Author(s):  
R. A. S. Brown ◽  
G. W. Govier
Keyword(s):  
High Speed ◽  
Two Phase Flow ◽  
High Speed Photography ◽  
Phase Flow ◽  
Two Phase

Cavitation-Induced Interface Instability of Droplet Between Plates

2019 ◽  
Author(s):  
Hongchen Li ◽  
Jingzhu Wang ◽  
Yiwei Wang
Keyword(s):  
High Speed ◽  
Industrial Applications ◽  
High Speed Photography ◽  
Affecting Factors ◽  
Interface Instability ◽  
Jet Formation ◽  
Wave Impact ◽  
Two Phase ◽  
Droplet Shape ◽  
Bubble Pulsation

Abstract Interface instability of droplet and formation of the liquid jet caused by internal volume oscillation are directly related to liquid pumping and mixing of microfluidic devices. Complex morphology jet enables liquid shaping, which is advantageous for industrial applications and biomedical engineering. In this study, the interface instability of cylindrical droplet between plates is investigated. The problem is analyzed through numerical simulation and experimentation. In the experiment, a single-pulse laser is used to generate cavitation at the center of the cylindrical droplet between two polymethyl methacrylate plates, and the physical progress is captured by high-speed photography. A compressible two-phase solver in the open source code OpenFOAM is used to simulate the 3D progress of bubble pulsation and droplet jet in consideration of viscosity and surface tension. Numerical methods adopt large eddy simulation. Results show that the interface density gradient is not collinear with the pressure gradient due to the shock wave impact and the bubble pulsation, that is, the baroclinic effect is the main cause of the instability at the droplet interface. The mechanism of the radial jet formation in the first period of bubble pulsation is closely related to the interface instability. A pair of vortex rings is formed under the influence of instability, thereby causing a stacking phenomenon on the jet head and eventually being cut. Affecting factors of the instability of the droplet interface are discussed. A high instability intensity of the droplet interface can be caused by a large initial bubble energy and a small contact angle. The instability strength of the droplet interface and the mode of jet formation are very sensitive to the curvature of the initial droplet shape. Relevant results may provide a reference for further understanding of interface instability and related engineering applications.

The Simulation of Air Fuel Mixing in High Swirl Open Chamber Diesel Engines

1976 ◽  
Vol 190 (1) ◽  
pp. 503-513 ◽  
Author(s):  
C. J. Morris ◽  
J. C. Dent
Keyword(s):  
High Speed ◽  
Swirl Flow ◽  
High Speed Photography ◽  
Combustion System ◽  
Mixing Process ◽  
Fuel Jet ◽  
Mixing Parameter ◽  
Fuel Mixing ◽  
System Geometry ◽  
Good Agreement

SYNOPSIS The air fuel mixing process in the high swirl open chamber diesel engine is simulated by a steady state gas jet injected into a steady air swirl flow. The results from the simulation show good agreement with engine studies using high speed photography. An attempt to quantify fuel dispersion has been made through the introduction of a mixing parameter, which allows for combustion system geometry in addition to fuel jet and air swirl momenta.

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