• Journal of the Korean Society of Visualization
• /
• v.20 no.2
• /
• pp.63-69
• /
• 2022

In this study, we numerically simulate the condensational growth of micron-sized particles traveling through a pipe filled with humidified air. Using the finite volume method and Lagrangian particle tracking technique, the mixture of particle-laden flow with moist air in a T-juction pipe is simulated. The condensational growth of particles is calculated by considering the mass transfer of vapor in the air onto the particle surface. The results indicate that the growth rate of the particles increases as the relative humidity of air is higher. Furthermore, the placement of a porous media with low permeability in the pipe could enhance the degree of condensational growth.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.6 no.1
• /
• pp.55-62
• /
• 2002

A new off-surface visualization method of using the micro water droplet and laser beam sheet was presented. About a size of 5 to TEX>$10\mu\textrm{m}$ micro water droplet could be made from home-style ultrasonic humidifier, A 3 W Argon ion laser and cylindrical lens were used to generate a laser beam sheet, which interrogate specific cross section of the vortical flow field. Application of this new visualization method was conducted in KAFA small-sized low speed wind tunnel of having the test section of 0TEX>$0.9 m(W){\times}$0.9 m(H){\times}2.1 m(L)$$$. Visualization results show this method relatively easy and safe flow visualization method for wind tunnel testing. Moreover, this method is also make up for the disadvantage of smoke visualization, and can be applied to higher flow velocity range than that of smoke visualization.

• Journal of Korea Multimedia Society
• /
• v.8 no.10
• /
• pp.1322-1328
• /
• 2005

The circulation flows passing through the Ekman boundary layer on the rotating disk and transfer the angular momentum into the interior region of the container. Consequently, the circulation enhances the momentum transfer and the interior fluid is divided by a propagating shear front. This investigation focuses on computer vision and image processing technique for analysis of Non-Newtonian Fluids. To visualize marching velocity shear front for the transient flow, a particular shaped particles and light are used. To validate the proposed method, quantitative image are compared with the optical data acquired by a direct measurement of LDV (Laser Doppler Velocimetry).

• Journal of the Korean Society of Visualization
• /
• v.1 no.1
• /
• pp.22-27
• /
• 2003

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05a
• /
• pp.575-580
• /
• 1997

반구형 간극에서의 비등시 이상 유체의 유동 가시화 실험을 수행하였다. 가시화를 위해 투명한 유리로 제작한 외부 용기는 내부의 가열 용기와 1mm 간격을 이루도록 하였으나 외부 용기가 완전한 반구 형태를 이루지 못하여 간극의 크기가 균일하지 못하였다. 열속이 높아짐에 따라 간극이 좁은 부분에서는 밖으로 빠져 나오려는 증기와 상부의 물이 역류유동제한 현상을 일으켜 물이 공급되지 못하였고 간극이 큰 부분에서는 물이 다수의 유로를 형성하며 증기와 분리되어 간극 내부로 공급되었다. CCFL 을 일으켜 물이 공급되지 못한 부분에서는 히터 표면이 건조되어 국부적인 CHF(Critical Heat Flux)가 발생하였다.

• 한국가시화정보학회:학술대회논문집
• /
• 2003.11a
• /
• pp.71-74
• /
• 2003

In this paper, we report the numerical and experimental results in a half-cylinder. In the numerical computation, we used the zonal embedded grid system. Flow visualization for the spin-up flows was used by PIV. The results show that at left hand side an cyclonic cell moves along a wall and separates into both cells at right hand side.

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.04c
• /
• pp.582-584
• /
• 2003

본 논문은 수중에서 유동하는 입자의 움직임을 추적하고 유체의 흐름에 따라 분산되는 입자의 분산정도 그리고 입자의 침강패턴을 분석하기 위한 계산형 3차원 시스템을 제안한다. 이러한 계산형 시스템은 물과 같은 공간에서 움직이는 입자들을 고려하고 있는데, 물의 흐름을 위해 운동량방정식과 연속방정식을 일반화하여 흐름을 제어하고 있다. 또한 물이라는 공간 특성을 고려하여, 입자간에 작용하는 부력, 침강력등의 물리적인 힘을 적용시키고 있다. 이렇게 제안된 시스템을 통해 다양한 외부적 요인에 따라 움직임을 달리하는 유동 입자들은 실제 울에서와 같이 유사하게 가시화되도록 한다. 이렇게 가시화된 유동 입자의 움직임을 추적하여 입자들의 침전패턴까지도 미1리 예측해 낼 수 있게 된다.

• 한국가시화정보학회:학술대회논문집
• /
• 2003.11a
• /
• pp.91-94
• /
• 2003

The present study addresses experimental results to investigate the details of the near field flow structures produced in the under-expanded, dual, coaxial, swirling, jet. The sonic swilling jets are emitted from a sonic inner nozzle and the outer annular nozzle produces the co/counter swirling streams against the primary swirling jet, respectively. The interactions between both the secondary annular swirling and primary inner supersonic swirling jets are quantified by the pilot impact and static pressure measurements, and visualized by using the Schlieren optical method. The experiment has been performed fur different swirl intensities and pressure ratios. The results obtained show that the secondary co-swirling jet significantly changes the inner under-expanded swirling jet, such as the recirculation zone, pressure distribution, through strong interactions between both the swirling jets, and the effect of the secondary counter-swirling jet on the primary inner jet is similar to the secondary co-swirl jet case.

• 한국가시화정보학회:학술대회논문집
• /
• 2006.12a
• /
• pp.11-16
• /
• 2006

Reverse flow occurs in a channel when there is an obstruction at the entry, However it has been shown recently that reverse flow can be realized without an obstruction, by staggering the sides of the channel and placing it at an angle of attack to the oncoming flow. In this study the latter flow is computationally investigated. And the mechanism is investigated using PIV (Particle Image Velocimetry) method. The results have captured all the essential features of this complex phenomenon and show the time dependent pumping mechanism which leads to the occurrence of reverse flow.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.2 no.3
• /
• pp.10-19
• /
• 1998

When an under-expanded supersonic jet impinges on an inclined flat surface, a complex flow structure is established due to the intersection between the flat surface and the shock system of the free jet. This study reports on an experimental results of flows due to under-expanded axisymmetric sonic jets impinging on flat plate. Plate inclination from $60^{\cire}$~$90^{\cire}$ were investigated by means of detailed measurements of the surface pressure and schlieren photograph and surface flow visualization. The schlieren photograph are consistent with the pressure distribution and the surface flow visualization pictures are clearly related to the pressure distributions. The maximum wall pressure is found to be large on the inclined plate than on the perpendicular plate.