• Proceedings of the KSME Conference
• /
• 2002.08a
• /
• pp.521-524
• /
• 2002

In the present study, kinetic energy of laminar steady flow in the exit region connected to the square-sectional $180^{\circ}$curved duct was investigated experimentally. The experimental study for air flows was conducted to measure kinetic energy distributions by using the Particle Image Velocimetry(PIV) system with the data acquisition and processing system of Cactus 2000 software. The results obtained from experimental studies are summarized as follows : (1) The critical Reynolds number for a change from laminar steady flow to transitional steadt flow was about 1910, in the 50 region of dimensionless axial position (x/Dh) whirh was considered as a fully developed flow region. (2) Maximum kinetic energy of laminar steady flow was gradually increased as the Reynolds number increased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.9 no.3
• /
• pp.268-275
• /
• 1997

Using the film-based particle image velocimetry, natural convective flows have been measured quantitatively in a rectangular enclosure with a heater located on the bottom surface. The success rate of the present interrogation method has been obtained as a function of the number of particle pairs and the distance between the particle pairs. The influence of the diffraction halo at the center have been effectively eliminated by rotating-subtracting the original Fourier-transformed image. By utilizing the coded multiple pulsed illumination with two different time intervals, the minimum measurable velocity have been improved. The results of the velocity distributions and the heat transfer correlations have been obtained for different locations of heater in the enclosure.

• Journal of Power System Engineering
• /
• v.20 no.6
• /
• pp.51-57
• /
• 2016

Experiment is carried out to investigate the mixed convective flow in three-dimensional horizontal rectangular channels filled with high viscous fluid. The particle image velocimetry(PIV) with thermo-sensitive liquid crystal tracers is used for visualizing and analysis. Quantitative data of temperature and velocity are obtained by applying the color-image processing to a visualized image, and neural network is applied to the color-to-temperature calibration. In this study, the fluid used is silicon oil(Pr=909), the aspect ratio(channel width to heigh) is 4 and Reynolds number is $2{\times}10^{-2}$. From the present study, we can visualize the quantitative temperature and velocity of mixed convective flow in three-dimensional horizontal rectangular channels simultaneously.

• Journal of the Korean Society of Visualization
• /
• v.10 no.3
• /
• pp.37-41
• /
• 2012

Plate-fin heat exchanger is a kind of compact heat exchangers with a good performance in heat transfer. It is widely used in various engineering fields such as aerospace, chemical and biomedical industries. Quantitative and qualitative flow visualization study were performed using the water model of commercial plate-fin heat exchanger with header angles of $30^{\circ}$. The Reynolds number was 100. Conventional digital particle image velocimetry was used to measure the instantaneous velocity fields of the header region and the flow visualization using dye injection and hydrogen bubble method were applied to capture the qualitative flow characteristics. The results showed the existence of separation flow region at the junction area and the bottom wall of the exit region.

• Journal of Ocean Engineering and Technology
• /
• v.18 no.3
• /
• pp.1-7
• /
• 2004

Flaw visualization and velocity field measurement methods have practical applications in the various fluid engineering fields, such as mechanics, ships, and heat fluids. In this study, the basic principles and theoretical methods are used to establish an application technique of Particle Imae Velocimetry(abbreviated to PIV below). Accordingly, the measured results of velocity field distribution of a section inside the Circulating Water Channel (abbreviated to CWC below) are computed using the PIV is presented. The uniformity of velocity distribution of the section in CWC is confirmed, by comparing this PIV data with the existing current meter data. Also, in order to measure the flaw fields of surroundings of 2-dimensional cylinder in the CWC, the flaw visualization technique using the PIV is applied.

• Journal of Ocean Engineering and Technology
• /
• v.32 no.4
• /
• pp.261-271
• /
• 2018

In this study, a hydraulic model test, to which Particle Image Velocimetry (PIV) system applied, was used to determine the hydrodynamic characteristics of the advection-diffusion of saltwater according to bottom conditions (impermeable/permeability, diameter, and inclination) and the difference of the initial salt. Considering quantitative and qualitative results from the experiment, the characteristics of the density current were discussed. As an experimental result, the advection-diffusion mechanism of salinity was examined by the shape of saltwater wedge and the flow structure of density currents with various bottom conditions. The vertical salt concentration obtained from the experiment was used as quantitative data to calculate the diffusion coefficient that was used in the numerical model of the advection-diffusion of saltwater.

• Journal of Mechanical Science and Technology
• /
• v.18 no.10
• /
• pp.1763-1771
• /
• 2004

An experimental investigation was performed to study the characteristics of ER (Electro-Rheological) fluid flow in a horizontal rectangular tube with or without D. C voltage. To determine some characteristics of the ER flow, 2D PIV(Particle Image Velocimetry) technique was employed for velocity measurements. This research found the mean velocity distributions with 0kV /mm, l.0kV /mm and l.5kV /mm for Re=0, 0.62, 1.29 and 2.26. When the strength of the electric field increased, the cluster of ERF was clearly strong along the test tube and the flow rate decreased. The present results will contribute to the economical and compact design of ER fluids system.

• Journal of Mechanical Science and Technology
• /
• v.18 no.10
• /
• pp.1799-1808
• /
• 2004

Knowledge of airflow characteristics in nasal cavity is essential to understand the physiological and pathological aspects of nasal breathing. Several studies have utilized physical models of the healthy nasal cavity to investigate the relationship between nasal anatomy and airflow. Since the final goal of these works is their contribution to the diagnosisand treatment of nasal diseases, the next step on this topic is naturally studies for disordered nasal cavities. In this paper, as the first application, airflows in the normal and abnormal nasal cavities with adenoid vegetation are investigated experimentally by PIV, and comparisons of both cases are appreciated. Dense CT data and careful treatment of model surface under the ENT doctor's advice provide more sophisticatedcavity model. The CBC PIV algorithm with window offset is used for PIV flow analysis. Average and RMS distributions are obtained for inspirational and expirational nasal airflows. Airflow characteristics that are related with the abnormalities in nasal cavity are presented.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.680-685
• /
• 2000

Liquid flow in a stirring mixer driven by a six-blade turbine has been investigated experimentally. The flows were quantified by measurements of velocity characteristics. obtained by a Particle Image Velocimetry(PIV). for a blade rotational speed of 100r.p.m. and for two blade clearances from the bottom of the tank. The instantaneous flow fields show that the bulk flow consists of small scale vortices very complicately. However, the mean flow results show that the formation of ring vortices above and below the blade. which depend on the clearance.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.925-930
• /
• 2000

This paper is investigated the entrainment of air into sprays which has significant effects on the combustion efficiency, stability of flame using the air-assisted twin-fluid nozzle in non-burning. The factors which may be expected to affect the entrainment of air by a liquid spray are: Relative velocity of droplet and ambient gas; Drop size and size distribution; Density and other property of the liquid. Here, axial, radial velocity and turbulent kinetic energy of spray droplet was measured with the PIV(Particle Image Velocimetry). Spray characteristics were also visualized using CCD camera. The results indicate that the entrainment rate increases more or less non-linearly with the downstream region.