• Proceedings of the Korean Society of Marine Engineers Conference
• /
• 2002.05a
• /
• pp.161-166
• /
• 2002

The resent experimental study is focused on the application of multi-point simultaneous measurement by PIV Particle Image Velocimetry) to guide vane region within diffuser pump. Various different kinds of rotational veto ity and changing clearance between Guide Vane and Impeller were selected as experimental condition. Optimized ross correlation identification to obtain velocity vectors is implemented with direct calculation of correlation coeffi cients. Fine optical setup concerned with PW performance is arranged for the accurate PW measurement of high peed complex flow. Variable flow pattern are represented quantitatively at the stator region.

• Journal of Advanced Marine Engineering and Technology
• /
• v.30 no.3
• /
• pp.413-419
• /
• 2006

The Industrial Mixers are used in various industrial fields where they are necessary to intimately mix two reactants in a short period of time. However, despite their widespread use, complex unsteady flow characteristics of industrial mixers are not systematically investigated. The present study aims for clarify unsteady flow characteristics induced by various impellers in a tank. Impellers are pitched blade turbine(PBT) types. Screw type and Rushton turbine type. In this study choice of the Industrial Mixer's Impeller type for distribution of concentration and PIV measurement method. The rotating speed of impellers are fixed by 100RPM.

• Proceedings of the KSME Conference
• /
• 2001.11b
• /
• pp.717-722
• /
• 2001

A present study is the flow characteristics of impinging jet by PIV measurement and numerical analysis. The flow characteristics of impinging jet flow are affected greatly by nozzle inlet velocity. An circular sharp edged nozzle type$(45^{\circ})$ was used to achieve uniform mean velocity at the nozzle inlet, and its diameter is 10mm(d). Therefore, the flow characteristics on the impinging jet can be changed largely by the control of main flow. In this parent study, we investigate the effects of inlet velocity, its variable is nozzle inlet Reynolds numbers(Re=1500, 3000, 4500, 6000 and 7500).

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.24 no.3
• /
• pp.459-466
• /
• 2000

Flow characteristics of turbulent elliptic jets were experimentally investigated using a single-frame PIV system. A sharp-edged elliptic nozzle with aspect ratio(AR) of 2 was tested and the experimental results were compared with those of circular jet having the same equivalent diameter($D_e$). The Reynolds number based on the nozzle exit velocity and nozzle equivalent diameter was about $1{\times}10^4$. The spreading rate along the major and minor axis are different remarkably. The jet half width along the major axis decreases at first and then increases with going downstream. But along the minor axis the jet width increases steadily. The elliptic jet of AR=2 has one switching points at $X/D_e=2$ within the near field. Turbulence properties are also found to be significantly different along the major and minor axis planes.

• Journal of Power System Engineering
• /
• v.3 no.2
• /
• pp.13-19
• /
• 1999

The purpose of the present experimental study is to apply multi-point simultaneous measurement by PIV(Particle Image Velocimetry) to high-speed flow region within a domestic boiler circulation pump. Two different kinds of flow rate($27{\ell}/min,\;19{\ell}/min$)are selected as experimental condition. A volute casing and Impeller made of transparent Polycarbonate were made for the easy access of the illumination laser via fiber optical line and cylinder lens assembly to the measuring region. A CCD camera is syncronized with AOM to acquire clear original particle images. Optimized cross correlation identification to obtain velocity vectors is implemented by direct calculation of correlation coefficients. The instantaneous and time-mean velocity distribution, velocity profile and kinetic energy are represented quantitatively at the full-scale region for the deeper understanding of the unsteady flow characteristics in a commercial circulation pump.

• Journal of Advanced Marine Engineering and Technology
• /
• v.20 no.5
• /
• pp.30-38
• /
• 1996

A PIV system consisting of an image board slit into personal computer and 2-D sheet light projector is developed and related techniques to improve its performance are discussed. A grey-level cross correlation method capable of overcoming particle seeding limitation is suggested. And a sub-pixed interpolation method in determining the vector terminal is preposed by considering 8-neighbours correlation distributing patterns. Furthermore, pressure estimation from the acquired velocity vectors by applying the Poisson equation is persented with reasonable feasibility. As a practical application of the present system, evaporator flows are analysed and attained instantaneous velocity vectors reveal that the flow phenomena maintain turbulent fluctuation.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.5
• /
• pp.587-593
• /
• 2004

In this paper, flow characteristics of plasma flow in a micro-tube were investigated experimentally using micro particle image velocimetry(micro-PIV). For comparison, the experiments were repeated for deionized(DI) wale. instead of plasma. Both velocity profiles of plasma and do-ionized water are well agreed with the theoretical velocity distribution of newtonian fluid. We also carried out generating plasma-in-oil droplet formation at a Y-junction microchannel. In order to clarify the hydrodynamic aspects involved in plasma droplet formation, Rhodamine-B were mixed with plasma only for visualization of plasma droplet. With oil as the continuous phase and plasma as the dispersed phase, plasma droplet can be generated in a continuous phase flow at a Y-junction. For given experimental parameters, regular-sized droplets are reproducibly formed at a uniform flow conditions.

• Journal of Advanced Marine Engineering and Technology
• /
• v.26 no.5
• /
• pp.573-580
• /
• 2002

Animation and time-resolved analysis of the wake characteristics of 2-D bluff body flows were examinated by applying the multi-vision PIV to square cylinders(three angles of attack: $0^{circ}, 30^{circ} and 45^{\circ}$) and circular cylinders(three rotating speeds: 0rpm, 76rpm, 153rpm) submerged within a circulating water channel $(Re=10^4)$, The macroscopic shedding patterns and their dominant frequencies were discussed in terms of instantaneous velocity, vorticity and turbulent quantities such as turbulent intensity, turbulent kinetic energy and three Reynolds stresses. Particularly the time-averaged distribution of turbulent intensity 'islands' where their peak magnitudes were focused always small regions behind the bodies without noticeable spatial migration were particularly discovered in all cases. And the dominant frequencies of the turbulent quantities in the wake regions were two times larger than those of the velocity and vorticity.

• Proceedings of the KSME Conference
• /
• 2000.04b
• /
• pp.667-672
• /
• 2000

The Characteristics of the conical vortices on the roof surface of a low-rise building has been investigated by using a PIV(Particle Image Velocimerty) technique. The scaled model of TTU building with 1:92 scaling ratio was used. The Reynolds number based on the free stream velocity and the length of the model was $1.96{\times}10^5$. When the angle of attack for the building model is $45^{\circ}$, the conical vortices are occurred symmetrically and the center of vortices are changed with respect to the angle of the approaching flow. The rotating direction of the conical vortices found to be counter-rotating. The secondary vortex motions are investigated using the instantaneous flow field data.

• Journal of the Korean Society of Visualization
• /
• v.4 no.2
• /
• pp.59-68
• /
• 2006

We have evaluated the performances of the following six interpolation schemes used for win-dow deformation in particle image velocimetry (PIV): the linear, quadratic, B-spline, cubic, sinc, Lagrange interpolations. Artificially generated images comprised of particles of diameter in a range pixel were investigated. Three particle diameters were selected for detailed evaluation: pixel with a constant particle concentration $0.02particle/pixel^2$. Two flow patterns were considered: uniform and shear flows. The mean and random errors, and the computation times of the interpolation schemes were determined and compared.