• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.4
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• pp.427-438
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• 1994

This experimental study was earned out to examine the heat transfer characteristics of a 2-dimensional impinging air jet on a flat plate with a set of square rods. The objectives of the study were to investigate the flow and heat transfer characteristics caused by the square rods and to find out the optimum rods arrangement. Experiment was carried out first without using the rods to establish the baseline heat transfer performance. Then, rods of different widths and clearances were installed to cause the turbulence on the fluid flow.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2000.11a
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• pp.37-42
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• 2000

The flow characteristics of impinging jet flow are affected greatly by nozzle plate to distances. An sharp edge nozzle 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 plate can be changed largely by the control of main flow. In the parent study, we investigate the effects of main flow length , its variable is nozle plate to distances( 12d, 10d, 8d, 6d and 4d).

• Wind and Structures
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• v.10 no.5
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• pp.437-462
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• 2007

A non-translating, long duration thunderstorm downburst has been simulated experimentally and numerically by modelling a spatially stationary steady flow impinging air jet. Velocity profiles were shown to compare well with an upper-bound of velocity measurements reported for full-scale microbursts. Velocity speed-up over a range of topographic features in simulated downburst flow was also tested with comparisons made to previous work in a similar flow, and also boundary layer wind tunnel experiments. It was found that the amplification measured above the crest of topographic features in simulated downburst flow was up to 35% less than that observed in boundary layer flow for all shapes tested. From the computational standpoint we conclude that the Shear Stress Transport (SST) model performs the best from amongst a range of eddy-viscosity and second moment closures tested for modelling the impinging jet flow.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.256-262
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• 1997

The characteristics of the unstable impinging circular jet were investigated based on the frequency characteristics and the sound field of the impinging-tones. Two symmetric modes Si and S2, associated with low frequency and high frequency respectively, and one helical mode H have been observed by measuring frequency and phase-distribution around the jet. Radiation characteristics of impinging-tone were studied by measuring axial directivity. It was founded that the radiation patterns of symmetric and helical mode are different and it is toward the plate as the impinging distance increased. By estimating the convection velocity of the unstable jet, it was founded that the convection speed decreases with the frequency and its decreasing pattern varies with unstable modes S1, S2 and H, respectively.

• Journal of computational fluids engineering
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• v.10 no.1
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• pp.39-44
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• 2005

The numerical investigation of the interaction between the underexpanded supersonic jet and the perpendicular plate is carried out using the TVD numerical method. The wave structure in the flowfield and the pressure and temperature distributions on the plate surface are obtained by the numerical analysis. Especially, the influence of self-induced flow oscillation caused by the impinging jet and the characteristic of impinging jet are shown. From the result of the numerical analysis, it is concluded that the pressure and the temperature fluctuations on the plate surface strongly depends on the pressure ratio in the flowfield and the position of plate.

• Proceedings of KOSOMES biannual meeting
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• 2009.06a
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• pp.87-88
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• 2009

In evaporating distillation plant velocity characteristic of fluid to flow in a evaporator have great influence on flash phenomenon. In This experimental study about impinging water jet region having the inflow of wall jet flow and effect of baffle height to flow velocity in after baffle region, making a application by PIV.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.278-284
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• 2000

The method of Impinging jet was applied lots of part in industrial field as a cooling of as gas turbine blade, a annealing of metal and plastic sheets, drying of textile, veneer paper, X-ray medical devices, laser weapons and electronic components. This study's main factor is reciprocating Jet impingement perpendicular to the heated Surface. We researched the effect of heat transfer and enhancement with pulsating air jet. The pulsating air jet has an improvement in pulsating Frequencies((f= 0.5, 1, 1.5, 3Hz) and nozzle-to-plate distances($l/d=\;2{\sim}4,\;6{\sim}8,\;4{\sim}6,\;8{\sim}10$).

• Proceedings of the KSME Conference
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• 2002.08a
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• pp.237-240
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• 2002

In the present study, we perform LES of turbulent flow and temperature fields in a circular impinging jet at Re=5000 for two cases of H/D=2 and 6 (H denotes the distance between the jet exit and flat plate, and D does the diameter of the jet exit). In the case of H/D=2, the regular vortical structures observed in free jet do not exist because of the smaller distance than the potential core. The Nusselt number on the wall is largest at $r/D{\cong}10.67$ where vortex rings Impinge. At $r/D{\cong}1.5{\~}2.0$, the vortex rings induce the secondary vortices, resulting in a secondary peak in the Nusselt number there. In the case of H/D=6, the vortex rings change into three-dimensional vortical structures and the small-scale vortices impinge on the flat plate. The increase of turbulent intensity due to small-scale vortices results in the largest Nusselt number at the stagnation point.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.5
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• pp.588-594
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• 1998

Heat transfer characteristics of distance between impinging surface and a plane jet were experi-mentally investigated. The local heat transfer coefficients were measured by a thermochromic liq-uid crystal(TLC) The jet Reynolds number studied was varied over the range from 10,000310 to 30,000310 the nozzle-to-plate distance (H/B) from 4 to 10. It was observed that the Nusselt number increases with Reynolds number the occurrence of the secondary peak in the Nusselt number is within the potential core region the potential core of the jet flow can reach the impinging surface so that the wall jet can a transition from laminar to turbulent flow resulting in a sudden increase in the heat transfer rate.

• Journal of the Korean Solar Energy Society
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• v.23 no.4
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• pp.55-61
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• 2003

Heat transfer characteristics for an air jet vertically impinging on a flat plate with a set of hybrid rods was investigated numerically using the RNG k-$\varepsilon$turbulent model. A commercial finite-volume code FLUENT is used. The rods had cross sections of half circular and rectangular shapes. The heating surface was heated with a constant heat flux value of $1020W/m^2$. Parameters investigated were the jet Reynolds number, nozzle -to-plate spacing, the rod pitch and rod-to-plate clearance. The local and average Nusselt number were found to be dependent on the rod pitch and the clearance because installing rods disturbed the flow. Higher convective heat transfer rate occurred in the whole plate as well as in the wall jet region.