• 해양환경안전학회:학술대회논문집
• /
• 해양환경안전학회 2009년도 춘계학술발표회
• /
• pp.87-88
• /
• 2009

증발식 담수화 설비에서 증발기로 유입되는 유동의 속도특성은 플래시현상에 중요한 영향을 미친다. 이 연구에서는 벽면제트류가 유입되는 충돌수분류영역과 배플후류영역의 유동 속도에 배플의 높이가 미치는 효과에 관해 PIV계측을 적용해 실험적으로 고찰하였다.

• 한국가시화정보학회:학술대회논문집
• /
• 한국가시화정보학회 2004년도 추계학술대회 논문집
• /
• pp.10-13
• /
• 2004

The PSP(pressure sensitive paint) technique has recently received a large attention as a new revolutionary optical method to measure absolute pressure distribution on a model surface. The PSP technique can be applied to quantitatively investigate flow structure using a CCD camera and image processing technique. In the static calibration, the luminescent intensity of PSP coatings was measured from 0kPa to 11kPa with 0.5, 1, 2kPa increments. In this study, the low-pressure PSP technique was applied to an oblique impinging jet to measure pressure field variations on the impingement plate with varying angle of an oblique jet. The flow structure over the impingement plate was visualized using a surface tracing method. As a result, the detail pressure field distributions of the oblique low-speed impinging jet were visualized effectively using the PSP technique.

• 설비공학논문집
• /
• 제6권4호
• /
• pp.427-438
• /
• 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.

• 한국기계가공학회지
• /
• 제10권6호
• /
• pp.102-108
• /
• 2011

The flow characteristics of unventilated dual impinging jets were experimentally investigated. Two nozzles with an aspect ratio of 20 were separated by 6 nozzle widths. The Reynolds number based on nozzle width and nozzle exit velocity was set to 5,000. A Particle Image Velocimetry (PIV) was used to measure turbulent velocity components. It was found that, when an impingement plate was installed in the converging region, there was a stagnation region in the inner area between nozzles. However, when it was installed in the combined region, both jets were merged and collided into the plate, showing single-jet characteristics. In addition, at a dual impinging jet, as the distance between a nozzle and an impingement plate decreased, the spanwise turbulent intensity at the plate increased.

• 한국가시화정보학회지
• /
• 제16권3호
• /
• pp.16-25
• /
• 2018

PIV experiments were carried out to visualize the velocity distribution of the sweeping jet impinging onto a flat plate and kinematic behavior of the jet from the fluidic oscillator. Two parameters such as four different Re cases and four different jet-to-wall distances were examined. Time-resolved two dimensional PIV measurements were performed for both streamwise and normal planes respect to the jet axis. Ensemble averaged and phase averaged velocity fields were obtained for the tested range of parameters. The sweeping frequency of the jet increases linearly with increase of Re. The kinetic energy of the sweeping jet decreases as the distance from the jet to the impinging plate increases. In addition, turbulence flow is generated due to the swinging motion of sweeping jet, and various vortices such as primary and secondary vortex are observed near the impinging wall.

• 대한기계학회논문집B
• /
• 제21권2호
• /
• pp.285-293
• /
• 1997

Numerical calculations has been performed for the flow and heat transfer to a circular cylinder from a hot circular impinging air jet. The characteristics of the flow and heat transfer are investigated and compared with the two-dimensional flow. The present study lays emphasis on the investigation on the flow and heat transfer of the three-dimensionality. The effects of the buoyancy force and the size of jet are also studied. The noticeable difference between the three and the two-dimensional cases is that there is axial flow of low temperature into the center-plane of the cylinder from the outside in the recirculation region. Local Nusselt number over the cylinder surface has higher value for the large jet as compared with that of the small jet since the energy loss of hot jet to the ambient air decreases with increase of the jet size. As buoyancy force increases the flow accelerates so that the period of cooling by the ambient air is reduced, which results in higher local Nusselt number over the surface.

• 대한기계학회논문집B
• /
• 제29권5호
• /
• pp.537-544
• /
• 2005

The present study numerically investigates two-dimensional fluid flow in the confined jet flow in the presence of applied magnetic field. Numerical simulations to calculate the fluid flow and heat transfer in the confined jet are performed for different Reynolds numbers in the absence and presence of magnetic fields in the range of $0{\le}N{\le}0.05$, where N is the Stuart number (interaction parameter) which is the ratio of electromagnetic force to inertia force. The present study reports the detailed information of flow in the channel at different Stuart numbers. As the intensity of applied magnetic fields increases, the vortex shedding formed in the channel becomes weaker and the oscillating amplitude of impinging jet decreases. The flow fields become the steady state if the Stuart number is greater than a critical value. Thus the pressure coefficients at the stagnation point also vary as a function of Stuart number.

• 한국전산유체공학회지
• /
• 제10권1호
• /
• pp.39-44
• /
• 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.

• Journal of Advanced Marine Engineering and Technology
• /
• 제21권1호
• /
• pp.37-42
• /
• 1997

Turbulent flow characteristics of a two - dimensional oblique plate impinging jet(OPIJ) were experimentally investigated. The jet mean velocity and turbulent intensity profIles were also measured along the plate. The jet Reynolds numbers(Re, based on the nozzle width)ranged from 10, 000 to 35, 000, the nozzle - to - plate distance(H/B) from 2 to 16, and the oblique angle (a) from 60 to 90 degree. It has been found that the stagnation point shifted toward the minor flow region as the oblique angle decreases and the position of the stagnation point nearly coin¬cided with that of the maximum turbulent intensity.

• 한국화재소방학회논문지
• /
• 제15권1호
• /
• pp.41-46
• /
• 2001

수평 평판과 충돌하는 제트에 의해 생성되는 연기유동을 관찰하기 위해 질소가스네 kerosene 연기입자를 띄워 유동장을 가시화하였다. 광원으로는 아르곤-이온 레이져 평면광이 사용되었다. Kerosene smoke의 산란 광에 의한 수직평면 상(image)과 수평평면 상을 고속 CCD 카메라와 비디오 카메라로 녹화하였으며, 얻어진 영상으로부터 연기선단의 순간속도 및 평균속도를 측정하였다.