• 동력기계공학회지
• /
• 제14권6호
• /
• pp.20-28
• /
• 2010

The computational flow analysis using LES technique was carried out to investigate the flow characteristics of a RAC chassis consisting of a rear-guider, a stabilizer and a cross-flow fan. The commercial SC/Tetra software was used in this analysis. In view of the results so far achieved, the distribution trends of static pressure and velocity vector of central region except the edges of a CFFan are similar regardless of the number of revolution, and an eccentric vortex exists around the bottom blade of a CFFan. Also, a reverse flow is found in the region between stabilizer and CFFan. Moreover, near the edges of a CFFan, an eccentric vortex is separated to two vortexes. Also these vortexes increase the velocity near a rear-guider, and guide the flow near a rear-guider into stabilizer inlet. Therefore, the reverse flow region is formed in the bottom of a CFFan.

• 동력기계공학회지
• /
• 제9권3호
• /
• pp.44-49
• /
• 2005

The aerodynamic performance of an indoor room air-conditioner using a cross-flow fan is strongly influenced by the various design factors of a rear-guider and a stabilizer. The purpose of this study is to investigate the effects of a rear-guider and a stabilizer on the aerodynamic performance in the maximum flowrate range of a cross-flow fan. The design factors considered in this study are a rear-guider clearance, a stabilizer cutoff clearance, and a stabilizer setup angle, respectively. Aerodynamic performances including maximum flowrate and power show the biggest magnitude distribution in the case of $45^{\circ}$, the stabilizer setup angle as well as nearly similar magnitude distribution regardless of the stabilizer cutoff clearances. Moreover, the more a rear-guider clearance increases, the more the magnitude of maximum flowrate and power increases.

• 동력기계공학회지
• /
• 제16권3호
• /
• pp.29-36
• /
• 2012

The computational flow analysis using LES technique was introduced to investigate the flow field improvement of an indoor RAC chassis consisting of a rear-guider, a stabilizer and a cross-flow fan. This unsteady three-dimensional numerical analysis was carried out by the commercial SC/Tetra software. The edge blocks were adopted in this study as a tool for the flow field improvement of an indoor RAC. In view of the results so far achieved, the edge blocks cause the center of an eccentric vortex to be stable along all length of a cross-flow fan, and then, the static pressure and the velocity vector show a stable distributions. In consequence, because the edge blocks eliminate a reverse flow near the edges, an exhausting flow becomes to be stable and uniform.

• 동력기계공학회지
• /
• 제9권3호
• /
• pp.33-38
• /
• 2005

The aerodynamic performance of a cross-flow fan is strongly influenced by the various design factors of a rear-guider and a stabilizer. The purpose of this paper is to investigate the effects of a rear-guider and a stabilizer on the aerodynamic performance of a cross-flow fan. The design factors considered in this paper are a rear-guider clearance, a stabilizer clearance, and a stabilizer setup angle, respectively. This experiment was carried out with a constant revolution number of 700 rpm in a cross-flow fan installed in the fan tester. The static pressure, flowrate, torque, and revolution number were measured in this paper. Also, the pressure coefficient and the efficiency were analysed according to the various assembly conditions using a stabilizer setup angle, a stabilizer clearance, and a rear-guider clearance in the indoor room air-conditioner.

• 동력기계공학회지
• /
• 제9권3호
• /
• pp.50-57
• /
• 2005

A cross-flow fan is strongly influenced by the various design factors of a rear-guider and a stabilizer. The purpose of this paper is to investigate the effects of a rear-guider and a stabilizer on the surface pressure of a rear-guider in an indoor room air-conditioner using a cross-flow fan. The design factors considered in this paper are a rear-guider clearance, a stabilizer clearance, and a stabilizer setup angle, respectively. The operating condition of a cross-flow fan was controlled by changing the static pressure and flowrate using a fan tester. All surface pressures of a rear-guider are differently distributed according to the stabilizer setup angle, and show a zero value in the flow coefficient, ${\Phi}{\fallingdotseq}0.5$ only of a stabilizer setup angle, $45^{\circ}$. Especially, they show a big negative value in the expansion angle larger than $34^{\circ}$ regardless of a rear-guider clearance, a stabilizer clearance, and a stabilizer setup angle. On the other hand, surface pressures for various stabilizer cutoff clearances are better than those for various rear-guider clearances.

• 한국임상수의학회지
• /
• 제32권1호
• /
• pp.101-104
• /
• 2015

4년령의 수컷 골든 리트리버 견이 복부 팽만 및 호흡곤란을 주증상으로 내원하였으며, 신체 검사 결과 부정맥과 심잡음이 청진되었다. 흉복부 방사선 검사 결과 전반적인 심비대, 흉수 및 복수가 관찰되었다. 심초음파 검사에서 비정상적인 승모판 및 삼첨판의 움직임과 역류가 관찰되었으며, 좌심실의 편심성 비대와 좌심방 비대가 보였다. 컬러 도플러 영상에서 확장기에 승모판 입구로부터 좌심실로 유입되는 와류가 관찰되었으며, 수축기에는 좌심방 및 우심방으로의 와류가 보였다. 도플러 검사로 확장기 승모판 유입 속도가 매우 증가하였으며 pressure half time이 지연되었다는 것을 알 수 있었다. 심초음파 검사 결과에 기초하여 승모판 협착증과 병발된 승모판 이형성증과 삼첨판 이형성증을 진단하였다.

• 한국전산유체공학회지
• /
• 제11권4호
• /
• pp.75-80
• /
• 2006

Navier-Stokes simulation of the flow in a micro viscous pump is carried out. The micro viscous pump consists of a rotating circular rotor placed in a two dimensional channel. All simulation is carried out by using a finite volume approach, at the Reynolds number of 0.5, to study the performance of the micro viscous pump. Length of channel of the pump is varied to simulate the effects of the pumping load. Numerical solutions show that the net flow of the pump is realized by two counter rotating vortices formed on both sides of the rotor. The volume flow rate of the pump is decreased as length of the channel is increased, while the static pressure difference across the rotor is increased. The static pressure difference across the rotor is observed to be inversely proportional to the volume flow rate as inertia effects are negligibly small. The efficiency of the pump is found to reach a maximum when two counter rotating vortices on both sides of the rotor becomes to merge forming an outer enveloping vortex.