Particle Image Velocimetry Measurements of the Three-Dimensional Flow in an Exhaust Hood Model of a Low-Pressure Steam Turbine

2006 ◽  
Vol 129 (2) ◽  
pp. 411-419 ◽  
Author(s):  
Wei Zhang ◽  
Bu Geun Paik ◽  
Young Gil Jang ◽  
Sang Joon Lee ◽  
Su Eon Lee ◽  
...  
Keyword(s):  
Flow Structure ◽  
Large Scale ◽  
Particle Image ◽  
Guide Vane ◽  
Three Dimensional ◽  
Vortical Flow ◽  
Exhaust Hood ◽  
Three Dimensional Flow ◽  
Image Velocimetry ◽  
End Wall

The three-dimensional flow structure inside an exhaust hood model of a low-pressure steam turbine was investigated using a particle image velocimetry (PIV) velocity field measurement technique. The PIV measurements were carried out in several selected planes under design operation conditions with simulated total pressure distribution and axial velocity profile. The mean flow fields revealed a complicated vortical flow structure and the major sources of energy loss. Vortices with different scales were observed inside the exhaust hood: a strong separation vortex (SV) behind the tip of the guide vane, a longitudinal vortex (LV) at the exhaust hood top, a large-scale passage vortex (PV) evolving throughout the flow path, and an end-wall vortex (EWV) in the region adjacent to the front end-wall. Both the SV and the large-scale PV seemed to consume large amounts of kinetic energy and reduce the pressure recovery ability. The results indicate that the steam guide vane and the bearing cone should be carefully designed so as to control the vortical flow structure inside the exhaust hood.

An Experimental Study on the Flow Structure inside a Display Cooler Using PIV Techniques

2006 ◽  
Vol 326-328 ◽  
pp. 167-170 ◽  
Author(s):  
Cheol Woo Park ◽  
In Je Baek ◽  
Jong Hwan Yoon
Keyword(s):  
Velocity Field ◽  
Flow Structure ◽  
Field Measurement ◽  
Large Scale ◽  
Particle Image ◽  
Base Plate ◽  
Vortical Flow ◽  
Piv Method ◽  
Image Velocimetry ◽  
Velocity Field Measurement

In the present study, the flow structure inside the refrigerating compartment of a scaleddown display cooler model was investigated experimentally using the particle image velocimetry (PIV) method, which is a reliable velocity field measurement technique. In addition, we also carried out flow visualization and computer simulations regarding the movements of thermo-fluid inside a display cooler. As a result, the velocity field measurement shows a large scale vortical flow structure inside the refrigerating compartment due to the entrained flow, thus penetrating a base plate through the open inlet gap.

Different Modes of Gas Entrainment Through Bottom Discharge Branch by Using Three Dimensional Particle Image Velocimetry System

2007 ◽  
Author(s):  
Wael Fairouz Saleh ◽  
Ibrahim Galal Hassan
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Structure ◽  
Particle Image ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Particle Image Velocimetry System ◽  
Three Dimension ◽  
Two Phase ◽  
Mean Velocity ◽  
Image Velocimetry

The discharge of two-phase flow from a stratified region through single or multiple branches is an important process in many industrial applications including the pumping of fluid from storage tanks, shell-and-tube heat exchangers, and the fluid flow through small breaks in cooling channels of nuclear reactors during loss-of-coolant accidents (LOCA). Knowledge of the flow phenomena involved along with the quality and mass flow rate of the discharging stream(s) is necessary to adequately predict the different phenomena associated with the process. Particle Image Velocimetry (PIV) in three dimension was used to provide detailed measurements of the flow patterns involving distributions of mean velocity, vorticity field, and flow structure. The experimental investigation was carried out to simulate two phase discharge from a stratified region through branches located on a semi-circular wall configuration during LOCA scenarios. The semi-circular test section is in close dimensional resemblance with that of a CANDU header-feeder system, with branches mounted at orientation angles of zero, 45 and 90 degrees from the horizontal. The experimental data for the phase development (mean velocity, flow structure, etc.) was done during single discharge through the bottom branch from an air/water stratified region over a three selected Froude numbers. These measurements were used to describe the effect of outlet flow conditions on phase redistribution in headers and understand the entrainment phenomena.

Experimental Study of the Transient Turbulence Generated by a Bubble Using PIV

1999 ◽  
Author(s):  
Javier Ortiz-Villafuerte ◽  
William D. Schmidl ◽  
Yassin A. Hassan
Keyword(s):  
Particle Image ◽  
Three Dimensional ◽  
Small Diameter ◽  
Three Dimensional Flow ◽  
Stagnant Water ◽  
Air Bubble ◽  
Image Velocimetry ◽  
Diameter Pipe ◽  
Transient Velocity ◽  
Bubble Rising

Abstract The particle image velocimetry measurement technique was used to measure the whole-volume, three-dimensional, transient velocity field generated by a single air bubble rising in stagnant water in a small diameter pipe. The three-dimensional flow field was reconstructed using a stereoscopic technique. Conditional averages of the velocity fields for the situations when the bubble rises close to the center of the pipe, and close to the pipe wall were determined, and the turbulent motion generated in the continuous liquid phase for both situations was studied.

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.

The unsteady three-dimensional wake produced by a trapezoidal pitching panel

2011 ◽  
Vol 685 ◽  
pp. 117-145 ◽  
Author(s):  
Melissa A. Green ◽  
Clarence W. Rowley ◽  
Alexander J. Smits
Keyword(s):  
Particle Image ◽  
Three Dimensional ◽  
Qualitative Change ◽  
Strong Interactions ◽  
Stream Velocity ◽  
Near Wake ◽  
Three Dimensional Flow ◽  
Trailing Edge ◽  
Image Velocimetry ◽  
Formation And Evolution

AbstractParticle image velocimetry (PIV) is used to investigate the three-dimensional wakes of rigid pitching panels with a trapezoidal geometry, chosen to model idealized fish caudal fins. Experiments are performed for Strouhal numbers from 0.17 to 0.56 for two different trailing edge pitching amplitudes. A Lagrangian coherent structure (LCS) analysis is employed to investigate the formation and evolution of the panel wake. A classic reverse von Kármán vortex street pattern is observed along the mid-span of the near wake, but the vortices realign and exhibit strong interactions near the spanwise edges of the wake. At higher Strouhal numbers, the complexity of the wake increases downstream of the trailing edge as the spanwise vortices spread transversely and lose coherence as the wake splits. This wake transition is shown to correspond to a qualitative change in the LCS pattern surrounding each vortex core, and can be identified as a quantitative event that is not dependent on arbitrary threshold levels. The location of this transition is observed to depend on both the pitching amplitude and free stream velocity, but is not constant for a fixed Strouhal number. On the panel surface, the trapezoidal planform geometry is observed to create additional vortices along the swept edges that retain coherence for low Strouhal numbers or high sweep angles. These additional swept-edge structures are conjectured to add to the complex three-dimensional flow near the tips of the panel.

The Application of Particle Image Velocimetry (PIV) in a Short-Duration Transonic Annular Turbine Cascade

1992 ◽  
Vol 114 (3) ◽  
pp. 504-509 ◽  
Author(s):  
P. J. Bryanston-Cross ◽  
C. E. Towers ◽  
T. R. Judge ◽  
D. P. Towers ◽  
S. P. Harasgama ◽  
...  
Keyword(s):  
Particle Image Velocimetry ◽  
Flow Field ◽  
Short Duration ◽  
Particle Image ◽  
Guide Vane ◽  
Three Dimensional ◽  
Film Plane ◽  
Test Facility ◽  
Image Velocimetry

A series of experiments have been performed to demonstrate the application of Particle Image Velocimetry (PIV) to turbomachinery flows. The tests were performed at transonic speeds on a fully annular engine size turbine nozzle guide vane. The vane cascade was installed in a short-duration Isentropic Light Piston Cascade (ILPC) test facility operating with high inlet turbulence levels. The technique has been shown to map the whole flow field with a resolution of 0.5 mm. The quality of the results obtained is not significantly affected by local turbulence rates. The accuracy of the measurements is put at around 4 percent of absolute velocity and is limited by the quality of the image on the film plane. The velocities derived from the PIV images have been compared with predictions from a three-dimensional viscous numerical calculation. It is shown that the experimental and predicted results are in good agreement. It is considered that this technique has considerable potential in application to turbomachinery flow field diagnostics.

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