• Proceedings of the KSME Conference
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• 2001.06e
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• pp.702-707
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• 2001

The characteristics of flow in dividing regions are precise, therefore their classification is very important not only in industry but also in hydrodynamics. By now, many studies of flow in dividing regions have been performed, but flow characteristics that use visualization in dividing regions have not been studied. The present study of the PIV and the CFD exhibit average velocity distributions, kinetic energy distributions and total pressure distributions etc of the total flow field due to the development of the accurate visualization optical laser and of optical equipment. Also, PIV is accurate with the flows characteristics of the dividing region as continuous analysis is done using input equipment. The study analyzes average velocity vector field, average kinetic energy, x-axis stress distributions, average and total pressure distributions of dividing regions with flow for visualization of the PIV and the CFD measurement in a dividing rectangular duct.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.270-275
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• 2001

The characteristics of flow in dividing regions are precise, therefore their classification is very important not only in industry but also in hydrodynamics. By now, many studies of flow in dividing regions have been peformed, but flow characteristics that use visualization In dividing regions have not been studied. The present study of the PIV and the CFD exhibit average velocity distributions, kinetic energy distributions and total pressure distributions etc of the total flow field due to the development of the accurate visualization optical laser and of optical equipment. Also, PIV is accurate with the flows characteristics of the dividing region as continuous analysis is done using input equipment. The study analyzes velocity vector field, turbulence kinetic energy, turbulence viscosity of dividing regions with flow for visualization of the PIV and the CFD measurement in a dividing rectangular ducts.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.633-638
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• 2000

Ultrasonic applications for the enhancement of turbulence flow by using the PIV measurement were carried out according to the angle of the ultrasonic oscillator, materials of the reflector and each section when ultrasonic is reflected several times. Angles of the ultrasonic oscillator such as $30^{\circ},\;45^{\circ},\;60^{\circ},\;90^{\circ},\;120^{\circ},\;135^{\circ}$ and $150^{\circ}$ were selected, and turbulent intensities were compared at Reynolds No. 2,000 and 4,000. Materials of the reflector such as wood, acryl, iron and glass were selected, and time mean velocity vector and turbulent intensity were compared at Reynolds No. 4,000. The zone which was observed was selected from first section to fourth section when ultrasonic was reflected several times. Every data such as time mean velocity vector and time mean turbulent intensity which was obtained by PIV measurement was examined, compared and discussed at Reynolds No. 2,000 and 4,000 to know the degree of turbulence enhancement in each case.

• The KSFM Journal of Fluid Machinery
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• v.5 no.4 s.17
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• pp.19-25
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• 2002

The flow characteristics in a bifurcated duct are investigated experimentally. Physical properties such as mean velocity vectors, mean vorticity, and total pressure distributions are obtained for three different Reynolds numbers (578, 620, 688) using PIV measurements and CFD analysis. Also, two different dividing ducts ($90^{\circ},\;60^{\circ}$) were selected for study. The results of this study would be useful to the engineers designing flow systems for heating, ventilation, air conditioning and waste-water purification plants.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.9
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• pp.1290-1306
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• 1998

An experimental study has been performed on a three-dimensional boundary layer over a rotating disk with an impinging jet at the center of the disk. The objective of the present study is to investigate the turbulence statistics of the three-dimensional turbulent boundary layer, which may be regarded as one of the simplest models for the flow in turbomachinery. Six components of the Reynolds stresses and ten triple products are measured by aligning the miniature X-wire probe to the mean velocity direction. The ratio of the wall-parallel shear stress magnitude to twice the turbulent kinetic energy in the near-wall region is strongly decreased by the impinging jet. In the case of the free rotating disk flow the shear stress vector lags behind the mean velocity gradient vector in the whole boundary layer, while the lag is weakened as the impinging jet speed increases.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.116-116
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• 1996

This paper is concerned with a method for calibrating five-hole probes of both angle-tube and prismatic geometries to measure local total and static pressures and the magnitude and direction of the mean velocity vector. Descriptions of the calibration technique, the typical calibration data, and an accompanying discussion of the interpolation procedure are included. The flow properties are determined explicitly from measured probe pressures using calibration data. Flow angles are obtained within the deviation angle of 1.0 degree and dynamic pressures within 0.03 with 95% certainty. The variations in the calibration data due to Reynolds number are also discussed. For the range of Reynolds number employed, no effect was detected on the pitch, yaw and total pressure coefficients. However, the static pressure coefficient showed change to cause minor variations in the magnitude of the calculated velocity vector. To account for these variations, average correction factors need to be incorporated into the static pressure coefficient.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.2
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• pp.48-56
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• 1996

This paper is concerned with a method for calibrating five-hole probes of both angle-tube and prismatic geometries to measure local total and static pressures and the magnitude and direction of the mean velocity vector. Descriptions of the calibration technique, the typical calibration data, and an accompanying discussion of the interpolation procedure are included. The flow properties are determined explicitly from measured probe pressures using calibration data. Flow angles are obtained within the deviation angle of 1.0 degree and dynamic pressures within 0.03 with 95% certainty. The variations in the calibration data due to Reynolds number are also discussed. For the range of Reynolds number employed, no effect was detected on the pitch, yaw abd total pressure coefficients. However, the static pressure coefficient showed change to cause minor variations in the magnitude of the calculated velocity vector. To account for these variations, average correction factors need to be incorporated into the static pressure coefficient.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.5
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• pp.679-685
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• 2009

In order to simulate a smoke or poisonous gas emergency in a rectangular tunnel and to investigate a better way to exhaust the smoke, the characteristics of smoke flow have been analyzed using flow field data acquired by Particle Image Velocimetry(PIV). Olive oil has been used as tracer particles with the kinematic viscosity of air, $1.51{\times}10^{-5}\;m^2/s$. The investigation has done in the range of Reynolds number of 1600 to 5333 due to the inlet velocities of 0.3 m/s to 1 m/s respectively. The average velocity vector and instantaneous kinematic energy fields with respect to the three different Reynolds numbers are comparatively discussed by the Flow Manager. In general, the smoke flow becomes more disorderly and turbulent with the increase of Reynolds number. Kinematic energy in the measured region increases with the increase of Reynolds number while decreasing at the leeward direction about the outlet region.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.225-234
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• 2001

This paper represents the vector fields, three dimensional mean velocities, the turbulent intensities, the turbulent kinetic energy, and the Reynolds shear stresses in the X-Y plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rates 350 and 450ℓ/min respectively, which are equivalent to the combustion air flow rate necessary for heat release 15,000 kcal/hr in gas furnace, in the test section of subsonic wind tunnel. The vector plot shows that the maximum axial mean velocity component exists in the narrow slits situated radially on the edge of gas swirl burner, for that reason, there is some entrainment phenomena of ambient air in the outer region of burner. Moreover, mean velocities in the initial region are largely distributed near the outer region of burner at Y/R≒0.97, but they diffuse and develop into the center flow region of burner according to the increase of axial distance. The turbulent intensities and the turbulent kinetic energy due to large inclination of mean velocity and swirl effect show that the maximum value in the initial region of burner is formed in the narrow slits situated radially on the edge of gas swirl burner and large values are mainly formed in the entire region of burner after X/R=2.4358, hence, the combustion reaction is anticipated to occur actively near this region. And the Reynolds shear stresses are also largely distributed from slite to vanes of gas swirl burner in the intial region, but their values largely disappear after X/R=3.2052.

• 한국가시화정보학회:학술대회논문집
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• 2004.12a
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• pp.41-45
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• 2004

The dynamic particle image velocimetry (PIV) is consisted of a high frequency pulse laser, high speed cameras and a timing controller. The three velocity components of flow downstream of an axial flow fan for PC cooling system are measured using the dynamic PIV system. An Axial flow fan has seven blades of 72 mm in diameter. The rotating speed is 1800 rpm. The downstream flow is visualized by smoke particles of about $0.3-1\;{\mu}m$ in diameter. The three-dimensional instantaneous velocity fields are measured at three downstream planes. The swirl velocity component was diffused downstream and the change in time-mean vorticity distribution downstream was also discussed. The spatio-temporal change in axial velocity component with the blades passing is recognized by the instantaneous vector maps. And the dynamic behavior of vorticity moving with the rotating blades is discussed using the unsteady vorticity maps.