Begell House Inc.
Journal of Flow Visualization and Image Processing
JFV
1065-3090
18
1
2011
A STUDY OF BUBBLE VENTING IN A MICROCHANNEL WITH HYDROPHOBIC NANOPOROUS MEMBRANES
1-10
10.1615/JFlowVisImageProc.v18.i1.10
Jin-Cherng
Shyu
National Kaohsiung University of Applied Sciences
Kai-Shing
Yang
Green Energy & Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu 31040, Taiwan
Wei-Shen
Chen
Department of Mechanical Engineering, National Yunlin University of Science & Technology, Yunlin 64002, Taiwan
Shih-Ying
Chang
Department of Mechanical Engineering, National Yunlin University of Science & Technology, Yunlin 64002, Taiwan
Chi-Chuan
Wang
Nantional Yang Ming Chiao Tung Univ
microchannel
bubble venting
porous membrane
A 500-μ;m-wide and 11-mm-deep cross-microchannel, which is made of copper and attached by a hydrophobic nanoporous membrane having a pore size of 0.22 μ;m and a porosity of 70%, is tested in the present study to examine the characteristics of gas/liquid two-phase flow in the microchannel in horizontal and vertical orientations during bubble venting via the hydrophobic nanoporous membrane. The mass flux tested in the present study is 5, 7.5, 10, and 12.5 kg/m2·s. In addition, the quality in the present study is tested from 0 to 0.08. The effects of mass flux, quality, and microchannel orientation on both the gas/liquid two-phase flow pattern and the bubble venting efficiency are examined in the present experiment through direct flow visualization. The tested results show that the farthest bubble movement distance increases with quality. It is also found that the flow rate of residual gas with the vertical arrangement is larger than that of the horizontal orientation. This is because the buoyancy force is in favor of the horizontal configuration for providing more direct contact and such contact of the bubble and the membrane is helpful for bubble venting. Besides, it is found that the higher flow rate of residual gas leads to a higher-pressure drop gradient in the flow channel.
NUMERICAL ANALYSIS ON THE RHEOLOGICAL CHARACTERIZATION AND FINISHING EFFICIENCY OF MRAFF PROCESS
11-28
10.1615/JFlowVisImageProc.v18.i1.20
Fuh-Lin
Lih
Center of General Education, R. O. C. Military Academy, Kaohsiung, Taiwan, R.O.C. and School of Defense Science Studies, Chung Cheng Institute of Technology, National Defense University, Taoyuan, Taiwan 335, R.O.C
Jr-Ming
Miao
Department of Materials Engineering, National PingTung University of Science & Technology, Shuefu Road, Neipu, Pingtung, Taiwan.
Chih-Wei
Kuo
Electro-Optics Section, Materials & Electro-Optics Research Division, Chung-Shan Institute of Science & Technology, Taoyuan, Taiwan, R.O.C.
Ying-Song
Li
Department of Vehicle Engineering, National Pingtung University of Science and Technology, Pingtung, Taiwan, R.O.C.
Chang-Hsien
Tai
Department of Vehicle Engineering, National Pingtung University of Science and Technology, Pingtung, Taiwan, R.O.C.
magnetorheological fluid
CFD
MRAFF
finishing efficiency
mesh number
Magnetorheological fluid consisting of nano-magnetic particles, featured by advantages, such as, short reaction time, good controllability, high stability, high shear stress and so forth, involves the advanced intelligent material. The said fluid can lead to a solid–liquid phase change under magnetic field, and thus change Newtonian fluid to non-Newtonian fluid, wherein the solid resembling mechanical property can be used to devise practical engineering parts different from traditional counterparts. Magnetorheological abrasive flow finishing (MRAFF) process is one of the technologies applying magnetorheological fluid to precision processing. However, because the mechanism, coupled with magnetic field, thermal flow field, and multiphase flow, is complicated, it is difficult to obtain parameters.
This research develops the numerical means to analyze the characteristics of magnetorheological fluids and the finishing efficiency of abrasives, and meanwhile, investigates the cutting efficiency on curved-surface parts and the variations in magnetorheological fluids using the characteristic equations of magnetorheological fluid under different mesh numbers, inlet pressures, and magnetic field intensities.
EXPERIMENTAL INVESTIGATION OF HEAT AND FLUID FLOW IN A TWO-PHASE HEAT TRANSPORT DEVICE WITH PARALLEL TUBES
29-43
10.1615/JFlowVisImageProc.2011002999
Thanh-Long
PHAN
Fujikura Ltd.
Akira
Murata
Department of Bio-Functions and Systems Science, Tokyo University of Agriculture and Technology, Nakacho, Koganei, Tokyo, Japan
Kaoru
Iwamoto
Department of Mechanical Engineering, Tokyo University of Science, Noda-shi, Chiba 278-8510; Department of Mechanical System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan
Hiroshi
Saito
Mechanical Systems Engineering Course, Tokyo Metropolitan College of Industrial Technology, 1-10-40 Higashi-Ohi, Shinagawa, Tokyo 140-0011,
Japan
heat transport device
phase change
flow visualization
flooding
heat transfer
A new type of two-phase heat transport device called the parallel-tube heat transport device (PTHTD) has been experimentally investigated for the heat transfer characteristics in its evaporator and condenser and for the attainable heat transport rate by using water as the working fluid. It consists of two rectangular chambers (50 × 50 × 10 mm) connected by five tubes in the same inner diameter of 3.6 mm. PT-HTD was tested in the vertical orientation with the lower chamber as the evaporator and the upper chamber as the condenser. A series of experiments was performed in the range of 20−1100 W heat transport rates and 0.3−2.0 filling ratio of the evaporator volume. It was found that the total thermal resistance of PT-HTD decreases with increasing heat input and is strongly dependent on heat transfer in the evaporator. The heat transport rate of PT-HTD is always higher than the maximum heat transfer rate by the flooding condition of an equivalent thermosyphon. Re-circulation of the working fluid inside the PT-HTD was observed in the wall temperature distribution of tubes measured by an infrared camera.
VISUALIZATION OF THE MIXING OF INTERMITTENT NATURAL GAS AND LIQUID DIESEL FUEL SPRAYS FROM HIGH-PRESSURE NOZZLES
45-73
10.1615/JFlowVisImageProc.2011002622
Timothy R.
White
School of Mechanical and Manufacturing Engineering, University of New South Wales, Sydney NSW 2052, Australia
Brian E.
Milton
Emeritus Professor, School of Mechanical and Manufacturing Engineering The University of New South Wales Sydney, NSW 2052 Australia
alternative fuels
gas fuels for diesel engines
fuel injection
high-speed shadowgraph
schlieren video
Dual fueling, with respect to compression ignition engines, is a process that allows the utilization of common alternative fuels that have a cetane number too low to be used alone. The alternative fuel requires the retention of diesel injection as a pilot ignition source. Conventional dual fueling pre-mixes the alternative fuel with air in the inlet manifold. However, this causes combustion problems, which limit the amount of fuel that can be substituted for the diesel. An alternative, studied here, is to directly inject both the alternative fuel as well as the original pilot diesel into the combustion chamber.
A purpose-built rig enabled the visualization of fuel jets into the simulated chamber of a diesel engine. Actual tests in an engine were not carried out since the purpose was to use good visualization to obtain details of the injection for modeling. Accordingly, repeatable, millisecond-duration flow visualization of these high-velocity events was essential — work that would have been very difficult in an engine. Jets of both liquid diesel and natural gas were injected into the chamber — first discretely and then with closely staged starting times — and photographed using the shadowgraph and schlieren techniques.
The relative positioning of the injectors for the different fuels with respect to each other as well as their relative timing were then examined and conclusions drawn as to the optimal layout and staging. Using this information, computational models were calibrated. These models formed the basis of computational fluid dynamics simulation of the dual-fuel injection into an actual engine.
IMAGE PROCESSING FOR SPACE TIME TRACKING OF SINGULAR POINTS METHOD FOR CHARACTERIZATION OF JET INSTABILITIES
75-90
10.1615/JFlowVisImageProc.2011002423
Taoufik
Filali
Unité de Métrologie en Mécanique des fluides et Thermique, Monastir University, Tunisia; and Hubert CURIEN Laboratory, Saint-Etienne University, France
Nabila
Filali
Unité de Métrologie en Mécanique des Fluides et Thermique (UMMFT), 03/UR/11-09, Ecole Nationale d’Ingénieurs de Monastir, Tunisie
Jacques
Jay
Thermal Science Centre of Lyon (CETHIL - UMR CNRS 5008) National Institute of Applied Sciences of Lyon Lyon, France
Habib Ben
Aissia
National School of Engineers of Monastir, Metrology Research Unit and Energy Systems, 5000 Monastir, Tunisia
air curtain
Kelvin-Helmholtz instabilities
jet parameters
singular points
spatiotemporal evolution
In this paper, we propose a tool image analysis and processing for the Kelvin-Helmholtz instability characterization. It is essentially based on a spatiotemporal tracking of singular points detected on the outline of images obtained by laser tomography. A number of characteristic parameters of the structures present along the flow are extracted allowing us to study the real jet evolution. The developed tool provides measurements of the amplification and velocity variations as well as a morphological classification of structures.