Begell House Inc.
Journal of Flow Visualization and Image Processing
JFV
1065-3090
6
3
1999
THE EFFECT OF A PARTITION ON SUPPRESSION OF THERMAL STRATIFICATION IN AN OPEN VESSEL WITH A HEAT SOURCE
157-165
10.1615/JFlowVisImageProc.v6.i3.10
Jun
Song
Department of Mechanical System Engineering, Gunma University 1-5-1, Tenjincho Kiryu, Gunma 376, Japan
Shigeaki
Inada
Department of Mechanical System Engineering, Gunma University, 1-5-1 Tenjincho, Kiryu, 376-8515, Japan
Wen-Jei
Yang
Department of Mechanical Engineering and Applied Mechanics University of Michigan, Ann Arbor, Michigan 48109-2125, U.S.A.
This article investigates theoretically the effects of partition on transient temperature distribution from a heat source in an open vessel. The effects of the partition on suppression of thermal stratification in the vessel are visualized graphically. The governing equations are solved by means of a finite difference technique for a wide range of parameters such as partition inclination angle, partition height, and partition location. The results clearly show that the flow pattern and temperature distribution in an open vessel are affected by changes in the parameters. There is an optimum inclination angle, partition height, and partition location for uniform temperature mixing performance in a vessel.
PIV EXPERIMENTS USING AN ENDOSCOPE FOR STUDYING PIPE FLOW
167-175
10.1615/JFlowVisImageProc.v6.i3.20
W.
Xiong
Lehrstuhl für Strömungslehre, Universität Essen, D-45117 Essen, Germany
Wolfgang
Merzkirch
Universitaet Duisburg-Essen,
Schwarzwaldstr. 18, 79102 Freiburg, Germany
The radial and tangential velocity components of the disturbed flow in a pipe are measured with PIV. The tracer particles illuminated with a light sheet normal to the pipe axis are imaged onto the recording camera through an endoscope. Swirl and vortical structures downstream of a 90° out-of-plane double bend can be measured. The results indicate that the flow immediately downstream of the bend is highly unsteady, and it must be concluded that the value of the usual time-averaged representations of this flow is questionable.
THREE-DIMENSIONAL MEASUREMENTS OF SCALAR DISSIPATION RATES IN A ZERO-MEAN-SHEAR TURBULENCE
177-187
10.1615/JFlowVisImageProc.v6.i3.30
S. S.
Shy
Department of Mechanical Engineering, National Central University, Chung-Li 32054, Taiwan
K. L.
Gee
Department of Mechanical Engineering, National Central University, Chung-Li 32054, Taiwan
E. I.
Lee
Department of Mechanical Engineering, National Central University, Chung-Li 32054, Taiwan
High-resolution, high-speed successive planar laser-induced fluorescence imaging of a synchronized swept laser beam, combined with a fast image-processing system, is used to measure a three-dimensional conserved scalar field ζ,(x, y, t) and/or ζ,(x, y, z) on the inner scale in an aqueous zero-mean-shear turbulent flow generated by vibrating grids. Each measuring image (1 cm × 1 cm) contains 256 × 256 pixels of which the measurement resolution reaches down to the local strain-limited molecular diffusion scale of the flow. Thus we can directly differentiate the resulting scalar field data to obtain the scalar energy dissipation rate field ∇ζ⋅∇ ζ,(x, t), allowing the local rate of molecular mixing in the flow to be investigated. It is found that for zero-mean-shear vibrating grid turbulent flows, fine scale mixing occurs in both strained laminar diffusion sheet-like layers and line-like tubes (roughly circular interactions are also observed) at which essentially all the dissipation is concentrated. This result is somewhat different from that of Dahm et al. (1991) in which no line-like structures are observed in a free shear turbulent jet flow, probably due to different types of turbulence applied.
VISUALIZATION EXPERIMENT AS A BASIS FOR ECOLOGIZATION OF METALLURGICAL PLANTS
189-204
10.1615/JFlowVisImageProc.v6.i3.40
Jiri
Nozicka
Czech Technical University in Prague, Faculty of Mechanical Engineering, Czech Republic
Josef
Adamec
Czech Technical University in Prague, Faculty of Mechanical Engineering, Technicka 4, 166 07 Prague, Czech Republic
This article reports on applying a combination of flow visualization on work in full scale with a visualization experiment on a scale model to an aerodynamic design of a ventilation system for an actual large-sized metallurgical plant. The primary visualization on the work was done both to obtain aerodynamic input data on each step of the technological process and to estimate the needed capacity of the ventilation system, to build a scale model for further testing. This model was then used for optimization development of the shape of basic aerodynamic elements by means of a combination of visualization experiments, measuring of flow parameters, and aerodynamic calculations.
FLOW VISUALIZATION ON THE LEEWARD SIDE OF THE UPSTREAM JUNCTURE OF A YAWED CIRCULAR CYLINDER
205-219
10.1615/JFlowVisImageProc.v6.i3.50
Yutaka
Hara
Department of Mechanical and Aerospace Engineering, Department of Applied Mathematics and Physics, Tottori University, 4-101 Koyama-cho, Tottori 680-0945, Japan
Hiroshi
Higuchi
Department of Mechanical, Aerospace and Manufacturing Engineering, Syracuse University, Syracuse, New York 13244-1240, USA
Tsutomu
Hayashi
Department of Applied Mathematics and Physics, Tottori University, 4-101 Koyama-cho, Tottori 680-0945, Japan
Flow on the leeward side of the upstream juncture of a yawed circular cylinder placed between two flat plates with yaw angle 60° was investigated with a dye flow visualization technique and particle image velocimetry (PIV). Strong three-dimensionality of the wake flow is observed behind the juncture part, including steady wake vortices along the cylinder and pairs of horseshoe and trailing vortices on the plate. A three-dimensional singular point was identified on the symmetry plane behind the upstream juncture and its effect on the vortex system and the wake flow is described.
SIMULTANEOUS MEASUREMENT OF VELOCITY FLUCTUATIONS AND SMOKE TRACER FLUCTUATIONS OF TURBULENT FLOW OVER A BACK-FACING STEP
221-229
10.1615/JFlowVisImageProc.v6.i3.60
M.
Novak
Turboinstitut Ljubljana, Rovsnikova 7, 1000 Ljubljana, Slovenija
M.
Hocevar
Turboinstitut, Rovsnikova 7, 1000 Ljubljana, Slovenia
Brane
Sirok
Faculty of Mechanical Engineering, University of Ljubljana, Askerceva 6, P.O. Box 394, SI - 1000 Ljubljana, Slovenia
K.
Oberdank
SIQ, Trzaska 2, 1000 Ljubljana, Slovenia
A correlation analysis of simultaneous measurements of velocity fluctuations taken by laser-doppler-anemometry (LDA), and of fluctuations of smoke tracer concentration measured with the aid of computer-aided visualization in selected segments of a turbulent flow field over a back-facing step was performed. In this article, results indicate that the two different techniques used, LDA for the velocity fluctuations and computer-aided visualization for the concentration measurements, provide accurate values when they are synchronized and analyzed separately. Simultaneous association of these two techniques allows us to determine the velocity-concentration correlations. The presented relationship between velocity and concentration fluctuations expresses fairly good agreement of both measured quantities.
ANALYSIS OF TURBULENT MIXING FLOW OF A BLUFF BODY WAKE USING A COMPUTER VISION SYSTEM
231-242
10.1615/JFlowVisImageProc.v6.i3.70
M.
Novak
Turboinstitut Ljubljana, Rovsnikova 7, 1000 Ljubljana, Slovenija
M.
Hocevar
Turboinstitut, Rovsnikova 7, 1000 Ljubljana, Slovenia
Brane
Sirok
Faculty of Mechanical Engineering, University of Ljubljana, Askerceva 6, P.O. Box 394, SI - 1000 Ljubljana, Slovenia
D. R.
Philpott
Aerospace Engineering, University of Hertfordshire, U.K.
P. R.
Bullen
Aerospace Engineering, University of Hertfordshire, U.K.
An experimental study of the turbulent mixing flow in the wake of a prismatic bluff body was made in a nonreturn subsonic wind tunnel (Reb = 4300 to 7400) using flow visualization and a digital image-processing technique. A high-speed camera was used to capture smoke visualization images of the turbulent mixing flow structures. A quantitative analysis was made on time series obtained by simultaneous digitization of the grey level in several small areas (windows) of the overall image. Fluctuations in grey level effectively corresponded to fluctuations in smoke concentration. Turbulent mixing structures in the wake exhibited various time signals and corresponding power spectra, which have been associated with space and time evolution of concentration fields. The results are compared to published velocity and concentration results.
VISUALIZATION OF THE DISSOLUTION BEHAVIOR OF A CO2 DROPLET INTO SEAWATER USING LIF
243-259
10.1615/JFlowVisImageProc.v6.i3.80
Baixin
Chen
Research Institute of Innovative Technology for the Earth, Mechanical Engineering Laboratory, AIST, MITI, 1-2, Namiki, Tsukuba-shi, Ibaraki 305-8564, Japan
Hiroshi
Akiyama
Research Institute of Innovative Technology for the Earth, Mechanical Engineering Laboratory, AIST, MITI, 1-2, Namiki, Tsukuba-shi, Ibaraki 305-8564, Japan
Masahiro
Nishio
National Institute of Advanced Industrial Science and Technology, 1-2-1 Namiki, Tsukuba, Ibaraki, 305-8564, Japan
Sequestration of liquid CO2 in the intermediate depth ocean has been considered as a means to reduce the atmospheric concentration of the greenhouse gas and to mitigate global warming. The dissolution behavior of CO2 in pure or seawater was investigated under high-pressure and low-temperature conditions in the intermediate ocean. Under these conditions, the CO2 clathrate hydrate film was formed at the interface between CO2 and (sea) water. The hydrate film has been considered to affect and decrease the dissolution rate.
The LIF technique was used in the experiments. LIF intensity showed the pH of CO2 dissolved water, while the CO2 droplet itself did not illuminate. Therefore, we could know the dissolution rate of CO2 and the nonuniform two-dimensional CO2 concentration distribution during the CO2 dissolution, with or without the CO2 hydrate film, in pure or seawater.