A Study of Hydraulic Characteristics of Multi-Square-Hole Orifice Plates

2012 ◽  
Vol 256-259 ◽  
pp. 2470-2473 ◽  
Author(s):  
Zhi Yong Dong ◽  
Yong Gang Yang ◽  
Qi Qi Chen ◽  
Bin Shi
Keyword(s):  
High Speed ◽  
Particle Image ◽  
Three Dimensional ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Hydraulic Characteristics ◽  
System Pressure ◽  
Image Velocimetry ◽  
Working Section ◽  
Square Hole

This paper experimentally investigated hydraulic characteristics in working section of multi-square-hole orifice plates of hydrodynamic cavitation reactor by use of three-dimensional Particle Image Velocimetry (PIV) and High Speed Photography etc. Arrangements of holes in the orifice plates can be divided into diagonal, cross and checkerboard categories. The three-dimensional velocity distribution, pressure and cavitation characteristics for each arrangement of multi-hole orifice plates were measured by PIV system, pressure data acquisition system and high speed camera, and a comparison of hydraulic characteristics of the three categories of arrangements of the multi-hole orifice plates were made.

Experimental and Numerical Study of Hydrodynamic Cavitation of Orifice Plates with Multiple Triangular Holes

2012 ◽  
Vol 256-259 ◽  
pp. 2519-2522 ◽  
Author(s):  
Zhi Yong Dong ◽  
Qi Qi Chen ◽  
Yong Gang Yang ◽  
Bin Shi
Keyword(s):  
Velocity Profile ◽  
High Speed ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Orifice Plate ◽  
Hydrodynamic Cavitation ◽  
High Speed Photography ◽  
Hydraulic Characteristics ◽  
Image Velocimetry

Hydraulic characteristics of orifice plates with multiple triangular holes in hydrodynamic cavitation reactor were experimentally investigated by use of three dimensional particle image velocimetry (PIV), high speed photography, electronic multi-pressure scanivalve and pressure data acquisition system, and numerically simulated by CFD software Flow 3D in this paper. Effects of number, arrangement and ratio of holes on hydraulic characteristics of the orifice plates were considered. Effects of arrangement and ratio of holes and flow velocity ahead of plate on cavitation number and velocity profile were compared. Distribution of turbulent kinetic energy and similarity of velocity profile were analyzed. And characteristics of cavitating flow downstream of the orifice plate were photographically observed by high speed camera. Also, a comparison with flow characteristics of orifice plate with hybrid holes (circle, square and triangle) was made.

scholarly journals Tomographic particle image velocimetry of desert locust wakes: instantaneous volumes combine to reveal hidden vortex elements and rapid wake deformation

2012 ◽  
Vol 9 (77) ◽  
pp. 3378-3386 ◽  
Author(s):  
Richard J. Bomphrey ◽  
Per Henningsson ◽  
Dirk Michaelis ◽  
David Hollis
Keyword(s):  
Particle Image Velocimetry ◽  
High Speed ◽  
Particle Image ◽  
Aerodynamic Force ◽  
Three Dimensional ◽  
Flow Fields ◽  
Diagnostic Methods ◽  
Tomographic Particle Image Velocimetry ◽  
Image Velocimetry ◽  
Spatio Temporal

Aerodynamic structures generated by animals in flight are unstable and complex. Recent progress in quantitative flow visualization has advanced our understanding of animal aerodynamics, but measurements have hitherto been limited to flow velocities at a plane through the wake. We applied an emergent, high-speed, volumetric fluid imaging technique (tomographic particle image velocimetry) to examine segments of the wake of desert locusts, capturing fully three-dimensional instantaneous flow fields. We used those flow fields to characterize the aerodynamic footprint in unprecedented detail and revealed previously unseen wake elements that would have gone undetected by two-dimensional or stereo-imaging technology. Vortex iso-surface topographies show the spatio-temporal signature of aerodynamic force generation manifest in the wake of locusts, and expose the extent to which animal wakes can deform, potentially leading to unreliable calculations of lift and thrust when using conventional diagnostic methods. We discuss implications for experimental design and analysis as volumetric flow imaging becomes more widespread.

Experimental measurement of large-scale three-dimensional structures in a turbulent boundary layer. Part 2. Long structures

2011 ◽  
Vol 673 ◽  
pp. 218-244 ◽  
Author(s):  
DAVID J. C. DENNIS ◽  
TIMOTHY B. NICKELS
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
High Speed ◽  
Large Scale ◽  
Particle Image ◽  
Three Dimensional ◽  
Velocity Fluctuations ◽  
Taylor’S Hypothesis ◽  
Image Velocimetry ◽  
Streamwise Structures

Three-dimensional (3D) measurements of a turbulent boundary layer have been made using high-speed particle image velocimetry (PIV) coupled with Taylor's hypothesis, with the objective of characterising the very long streamwise structures that have been observed previously. The measurements show the 3D character of both low- and high-speed structures over very long volumes. The statistics of these structures are considered, as is their relationship to the important turbulence quantities. In particular, the length of the structures and their wall-normal extent have been considered and their relationship to the other components of the velocity fluctuations and the instantaneous stress.

Analysis of Simultaneous Velocity and Density Distributions for High-Speed CO2 Flow Using Particle Image Velocimetry and Digital Speckle Tomography

2006 ◽  
Vol 326-328 ◽  
pp. 55-58 ◽  
Author(s):  
Han Seo Ko ◽  
Yong Jae Kim ◽  
Oh Chae Kwon ◽  
Koji Okamoto
Keyword(s):  
Particle Image Velocimetry ◽  
High Speed ◽  
Particle Image ◽  
Three Dimensional ◽  
Jet Flow ◽  
Initial Flow ◽  
Density Distributions ◽  
Image Velocimetry ◽  
Digital Speckle ◽  
Tomography Method

Velocity and density distributions of a high-speed and initial CO2 jet flow have been analyzed simultaneously by a developed three-dimensional digital speckle tomography and a particle image velocimetry (PIV). Three high-speed cameras have been used for the tomography and the PIV since a shape of a nozzle for the jet flow is asymmetric and the initial flow is fast and unsteady. The speckle movements between no flow and CO2 jet flow have been obtained by a cross-correlation tracking method so that those distances can be transferred to deflection angles of laser rays for density gradients. The three-dimensional density fields for the high-speed CO2 jet flow have been reconstructed from the deflection angles by the real-time tomography method, and the two-dimensional velocity fields have been calculated by the PIV method simultaneously.

Experimental Investigation Into Unsteady Effects on Film Cooling

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Richard J. Fawcett ◽  
Andrew P. S. Wheeler ◽  
Li He ◽  
Rupert Taylor
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Particle Image ◽  
High Speed Photography ◽  
Velocity Difference ◽  
Cooling Flows ◽  
Blowing Ratio ◽  
Image Velocimetry ◽  
Mainstream Flow ◽  
Unsteady Effects

The benefits of different film cooling geometries are typically assessed in terms of their time-averaged performance. It is known that the mixing between the coolant film and the main turbine passage flow is an unsteady process. The current study investigates the forms of unsteadiness that occur in engine-representative film cooling flows and how this unsteadiness affects the mixing with the mainstream flow. Cylindrical and fan-shaped cooling holes across a range of hole blowing ratios have been studied experimentally using particle image velocimetry and high speed photography. Coherent unsteadiness is found in the shear layer between the jet and the mainstream for both cylindrical and fan-shaped cooling holes. Its occurrence and sense of rotation is found to be controlled by the velocity difference between the mainstream flow and the jet, which is largely determined by the blowing ratio.

Large Eddy Simulation (LES) and Time-Resolved Particle Image Velocimetry (TR-PIV) in the Wake of a Cavitating Hydrofoil

2005 ◽  
Author(s):  
Martin Wosnik ◽  
Qiao Qin ◽  
Damien T. Kawakami ◽  
Roger E. A. Arndt
Keyword(s):  
Particle Image Velocimetry ◽  
Large Eddy Simulation ◽  
High Speed ◽  
Particle Image ◽  
Three Dimensional ◽  
Pair Type ◽  
Time Resolved ◽  
Eddy Simulation ◽  
Image Velocimetry ◽  
Large Eddy

A Large Eddy Simulation (LES) approach for cavitating flow, based on a virtual single-phase, fully compressible cavitation model which includes the effects of incondensable gas, has been shown to be capable of capturing the complex dynamical features of highly unsteady cavitating flows of two-dimensional hydrofoils. Here the LES results are compared to Time-Resolved Particle Image Velocimetry (TR-PIV) in the wake of a cavitating NACA 0015 hydrofoil, with particular attention to the predicted vortex shedding mechanisms. Despite some difficulty with obtaining vector fields from vortical clouds of vaporous-gaseous bubbles with cross-correlation techniques, the initial results seem promising in that they confirm the existence of a primary vortex pair (type A-B). In addition to TR-PIV, the cavitation cloud shedding was also documented with phase-locked, time-resolved photography and high speed volume-illuminated video, both with simultaneous imaging of side and plan views of the foil. All three experimental techniques confirm the need for fully three-dimensional simulations to properly describe the unsteady, three-dimensional cavitation cloud shedding mechanism.

Experimental Investigation Into Unsteady Effects on Film Cooling

2010 ◽  
Author(s):  
Richard J. Fawcett ◽  
Andrew P. S. Wheeler ◽  
Li He ◽  
Rupert Taylor
Keyword(s):  
Film Cooling ◽  
High Speed ◽  
Particle Image ◽  
High Speed Photography ◽  
Velocity Difference ◽  
Cooling Flows ◽  
Blowing Ratio ◽  
Image Velocimetry ◽  
Mainstream Flow ◽  
Unsteady Effects

The benefits of different film cooling geometries are typically assessed in terms of their time averaged performance. It is known that the mixing between the coolant film and the main turbine passage flow is an unsteady process. The current study investigates the forms of unsteadiness which occur in engine-representative film cooling flows, and how this unsteadiness affects the mixing with the mainstream flow. Cylindrical and fan-shaped cooling holes across a range of hole blowing ratios have been studied experimentally using Particle Image Velocimetry and High Speed Photography. Coherent unsteadiness is found in the shear layer between the jet and the mainstream, for both cylindrical and fan-shaped cooling holes. Its occurrence and sense of rotation is found to be controlled by the velocity difference between the mainstream flow and the jet which is largely determined by the blowing ratio.

Hydraulic Balance Ring Study and Design Using Optical Techniques

2011 ◽  
Author(s):  
Alfonso Thompson-Salinas ◽  
Martin Ortega-Bren˜a ◽  
Manuel H. De la Torre-Ibarra ◽  
Bernardino Barrientos-Garci´a ◽  
Victor J. Gonzalez-Villela
Keyword(s):  
Particle Image Velocimetry ◽  
High Speed ◽  
Particle Image ◽  
High Speed Photography ◽  
Washing Machine ◽  
Optical Techniques ◽  
New Approach ◽  
Image Velocimetry ◽  
Hydraulic Balance ◽  
Velocity Field Measurement

A new approach to understand factors that affect self-balancing devices is proposed. Experimentation was conducted to determine the influence of different factors on the performance of an automatic washing machine hydraulic balance ring fluid during transient and steady states. Two different optical techniques were used: one for visualization (high-speed photography) and another for velocity field measurement (Particle Image Velocimetry, PIV). Results were used to build a new balancer design and compared with previous findings. Important factors in balancer design were deducted.

Study of Layer Formation During Droplet-Based 3D Printing of Gel Structures

2017 ◽  
Author(s):  
Kyle Christensen ◽  
Yong Huang
Keyword(s):  
3D Printing ◽  
Inkjet Printing ◽  
High Speed ◽  
Particle Image ◽  
Three Dimensional ◽  
Layer By Layer ◽  
Layer Formation ◽  
High Speed Imaging ◽  
Drop On Demand ◽  
Image Velocimetry

Additive manufacturing, also known as three-dimensional (3D) printing, is an approach in which a structure may be fabricated layer by layer. For 3D inkjet printing, droplets are ejected from a nozzle and each layer is formed droplet by droplet. Inkjet printing has been widely applied for the fabrication of 3D biological gel structures, but the knowledge of the microscale interactions between printed droplets is still largely elusive. This study aims to elucidate the alginate layer formation process during drop-on-demand inkjet printing using high speed imaging and particle image velocimetry. Droplets are found to impact, spread, and coalesce within a fluid region at the deposition site, forming coherent printed lines within a layer. Interfaces are found to form between printed lines within a layer depending on printing conditions and printing path orientation. The effects of printing conditions on the behavior of droplets during layer formation are discussed and modeled based on gelation dynamics, and recommendations are presented to enable controllable and reliable fabrication of gel structures.

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