Begell House Inc.
Journal of Flow Visualization and Image Processing
JFV
1065-3090
16
3
2009
CFD SIMULATION OF A GAS MASK FILTER IN THREE REALISTIC BREATHING PATTERNS
201-219
10.1615/JFlowVisImageProc.v16.i3.10
Yin-Chia
Su
Master Program of Mechanical Engineering, Chung Cheng Institute of Technology, National Defense University, Taoyuan, Taiwan 335, R.O.C.
Chun-Chi
Li
Chung Cheng Institute of Technology, National Defense University
CFD
gas mask canister
porous media
inspiratory resistance
extra work of breathing
This research adopts CFD tools to investigate the influence of inspiratory resistance and extra work of breathing towards the users under three realistic breathing patterns (resting, light activity, and moderate exercise). The calculation model adopts the transient Navier−Stokes equation with the low Reynolds number k−ε turbulent model to find the solution. Besides, the momentum loss of porous flow calculated by the porous media equation is added in the source term of the momentum equation to present a larger pressure drop in porous media domain. The simulation results reveal that the maximum inspiratory resistance for Model A1 under moderate exercise is 2.35 times of light activity and 4.94 times of resting condition. In addition, the maximum of extra breathing work for moderate exercise is 4.83 times of light activity and 19.89 times of resting condition. Under realistic breathing patterns, the changes of the exercise strength in human will lead to the proportional changes in inspiratory resistance and extra work of breathing when wearing the gas mask. Subsequently, the characteristics of the respiratory physiology will be altered and the cardio-pulmonary load of the users will be increased.
MICRO-PARTICLE IMAGE VELOCIMETRY VISUALIZATION OF WATER FLOW IN A COMPLEX MICRO-HEAT EXCHANGER
221-236
10.1615/JFlowVisImageProc.v16.i3.20
Stephen A.
Solovitz
Washington State University Vancouver, 14204 NE Salmon Creek Ave., Vancouver, WA, USA 98686
Amir
Jokar
Exponent Inc.
micro-heat exchanger
CFD simulations
microchannel cooler
micro-PIV
The fluid dynamics of water flow in a complex micro-heat exchanger for electronics cooling applications have been examined using micro-particle image velocimetry (PIV) methods. Instantaneous and ensemble-averaged flow fields have been measured at several locations within a series of tortuous, serpentine microchannels at a range of Reynolds numbers between 375 and 1180, based on a channel hydraulic diameter of about 381 microns. The flow response has been directly compared with previously developed computational fluid dynamics (CFD) simulations to validate those predictions. The velocity profiles obtained from the two methods agreed reasonably well within the measurement uncertainty for most conditions. These results further demonstrate the utility of micro-PIV as a validation tool for complex geometry CFD simulations.
EVOLUTION OF PARTICLE DIAMETERS AND PARTICLE VELOCITIES DURING LIQUID METAL ATOMIZATION
237-253
10.1615/JFlowVisImageProc.v16.i3.30
A.
Allimant
UTBM-LERMPS, Site de Sévenans, 90010 Belfort Cedex
Marie-Pierre
Planche
LERMPS, Technological University of Belfort- Montbéliard, site de Sévenans, 90010 Belfort Cedex France
L.
Dembinski
UTBM-LERMPS, Site de Sévenans, 90010 Belfort Cedex
Christian
Coddet
LERMPS, Université de Technologie de Belfort-Montbéliard, site de Sévenans, 90 010 Belfort Cedex
Yannick
Bailly
FEMTO-ST Institute, Univ. Bourgogne Franche-Comté, CNRS, Belfort, France
L.
Girardot
Institut FEMTO-ST-UMR 6174, Département Energie, Université de Franche-Comté, Parc Technologique, Belfort, France
metal atomization
De Laval nozzle
particle image velocimetry
powder characteristics
Gas atomization of liquid metal using the De Laval nozzle is one of the most efficient processes in terms of powder quality including size and composition criteria and in terms of inert gas consumption used to atomize liquid metal. However, the comprehension of the involved events is at that time of prime importance to optimize this process and the researches are focused on both experimental and modelling approaches. For example, very few experimental data are available on liquid metal atomization because of the difficulty to achieve measurements very close to the atomization area. The paper concerns some experimental results obtained with Al−5 wt.% Mn metal spraying. The evolution of the powder characteristics, i.e., particle-size distribution and particle velocity during the process were investigated. Then, some particles were collected in different samples during the atomization process and the relationship between the atomizing pressure and the resulting powder size was analyzed. The particle image velocimetry (PIV) has been used to measure the particle velocity in the atomizing chamber. The results were determined as a function of the process parameters.
RELIABILITY OF 5-BEAM LDV FIBEROPTIC PROBE FOR TURBULENCE MEASUREMENTS IN THE WALL REGION OF OPEN-CHANNEL FLOW
255-277
10.1615/JFlowVisImageProc.v16.i3.40
Samuele
de Bartolo
Dipartimento di Difesa del Suolo, Università della Calabria, Via P. Bucci 42b, 87036 Rende (Cosenza)
Roberto
Gaudio
Dipartimento di Difesa del Suolo, Università della Calabria, Via P. Bucci 42b, 87036 Rende (Cosenza)
Giancarlo
Alfonsi
Fluid Dynamics Laboratory, Universita della Calabria, Via P. Bucci 42b, 87036 Rende (Cosenza), Italy
Leonardo
Primavera
Fluid Dynamics Laboratory, Universita della Calabria, Via P. Bucci, Cubo 42b, 87036 Rende (Cosenza), Italy
laser Doppler velocimetry
turbulence
open-channel flow
A 5-beam LDV fiberoptic probe is used for an experimental investigation of turbulent open (water) channel flow at ReτH = 601 (the Reynolds number based on friction velocity and hydraulic radius). The performances of the instrument are mainly investigated in the region near the bottom wall of the open channel, with regard to both mean and fluctuating velocity components, and the results are compared with the data of numerical nature related to DNS calculations, as performed in the case of the plane channel (the flow between two parallel plates) at a very close value of the Reynolds number. Due to the different flow conditions along the vertical direction in the experimental open channel and in the numerical plane channel, near-wall comparisons are considered only for the streamwise- and spanwise-velocity components.