• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.809-812
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• 2006

This article shows the study on the arresting sound occurrence due to the interaction of the centrifugal Fan and bellmouth suction flow with bellmouth height as variable. It has accomplished to measure of inlet noise and also to analysis suction pressure distribution through experiment and also using CFD. The main cause of sound occurrence was judged with the effect due to static pressure change of bellmouth surface.

• International Journal of Fluid Machinery and Systems
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• 제7권2호
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• pp.60-67
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• 2014

In order to clarify the effect of inlet bellmouth size of semi-opened type axial fan on its performance and flow fields around rotor, fan test and flow field measurements using hotwire anemometer were carried out for 6 kinds of bellmouth size. As results of fan test, the shaft power curve hardly changed, even if the bellmouth size changed. On the other hand, the pressure-rise near best efficiency point became small with the bellmouth size decreasing. Therefore, the value of maximum efficiency became small as the bellmouth size decreased. As results of flow field measurements at fan inlet, the main flow region with large meridional velocity existed near blade tip when the bellmouth size was large. As bellmouth size became smaller, the meridional velocity at fan inlet became smaller and the one at outside of blade tip became larger. As results of flow field measurements at fan outlet, the main flow region existed near rotor hub side.

• 동력기계공학회지
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• 제17권6호
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• pp.73-78
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• 2013

A Small-size axial fan(SSAF) has widely been utilized to circulate a cooling air in a refrigerator, etc. Generally, the aerodynamic performance of SSAF is strongly dependent upon the depth between SSAF and bellmouth, and it includes axial, partially stalled, mostly stalled and radial flow regions according to the flow coefficient. In this study, four kinds of bellmouth depths were considered to analyze the aerodynamic performance of SSAF. As a bellmouth depth increases, a maximum flowrate decreases, but a maximum static pressure increases. Also, stall region includes an inflection point in all aerodynamic performance curves. Finally, a static pressure efficiency shows the maximum value of 37%.

• 한국추진공학회지
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• 제16권4호
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• pp.70-79
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• 2012

공력학적 성능을 평가하는 대형 유동 시험장치에서 시험체 입구로 들어가는 유체의 압력, 온도, 유량등은 시험체의 성능 계산에 필수적인 항목이므로, 이 값들을 정확하게 측정하는 것이 중요하다. 본 논문에서는 벨마우스와 레이크를 사용하여 보정 유량 범위가 5 ~ 8 kg/s인 대용량 유량을 계측하는 방법을 연구하였다. 벨마우스는 ISO Standard를 따라 0.5% 정확도를 만족할 수 있도록 설계하였고, 레이크는 등면적으로 배치하도록 설계하였다. 총 9 회의 서로 다른 조건의 시험을 분석한 결과 레이크 레이놀즈 수와 유량값의 비가 1차 함수 관계에 있음을 확인하였고, 이 관계식을 이용하여 레이크의 유량값을 벨마우스의 값을 기준으로 최대 -0.507%, 평균 -0.000274% 오차율로 보정할 수 있었다.

• 동력기계공학회지
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• 제19권6호
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• pp.19-25
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• 2015

The unsteady-state, incompressible and three-dimensional large eddy simulation(LES) was carried out to analyze the aerodynamic performance of three-dimensional small-size axial fan(SSAF) with the different depth of bellmouth. The static pressure coefficients analyzed by LES predict a little bit larger than measurements except stall region regardless of the installation depth between SSAF and bellmouth. Moreover, static pressure efficiencies analyzed by LES show about maximum 30% at the actual operating point ranges, but measurements do not. Therefore, if the blades of conventional SSAF have some more rigidity and complete dynamic balance, the aerodynamic performance of SSAF will be some more improved. In consequence, LES shows the best prediction performance in comparison with any other Reynolds averaged Navier-Stokes(RANS) method.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.93-96
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• 2004

A turbo-fan for the 4-way cassette indoor units of air-conditioners has been investigated. The main purpose of this investigation is the reduction of the turbo-fan noise. In order to reduce the noise level, many design parameters of turbo-fans such as blade section, blade thickness, geometry of blade leading edge, blade width, blade angle and bellmouth depth have been studied. With the experimental data of these parameters, a new turbo-fan was made for our system. The noise level of the new system was at least 3 dB(A) lower than that of the current in use.

• 동력기계공학회지
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• 제16권4호
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• pp.51-59
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• 2012

The computational flow analysis using LES technique was carried out to investigate the flow characteristics of a sirocco fan under the maximum flowrate condition. The commercial SC/Tetra software was used for this unsteady and three-dimensional numerical analysis. In consequence, because a flow is unstable within the range of about 50% of a housing depth from a bellmouth around the cutoff region, the passing flow through the blade cascade occurred on the X-Y plane is a slow or a reverse with approaching to the housing inlet. Also, the secondary flow shows on the radial plane of a housing, and its vortex center exists within about 33% of a housing depth from a bellmouth except the cutoff region. Moreover, the flow occurring on the exit plane of a sirocco fan shows a complex secondary flow.

• International Journal of Fluid Machinery and Systems
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• 제4권3호
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• pp.307-316
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• 2011

In order to clarify the features of tip leakage vortex near blade tip region in a half-ducted axial fan with large bellmouth, the experimental investigation was carried out using a 2-dimensional LDV system. Three sizes of tip clearance (TC) were tested: those sizes were 1mm (0.55% of blade chord length at blade tip), 2mm (1.11% of blade chord length at blade tip) and 4mm (2.22% of blade chord length at blade tip), and those were shown as TC=1mm, TC=2mm and TC=4mm, respectively. Fan characteristic tests and the velocity field measurements were done for each TC. Pressure - flow-rate characteristics and two-dimensional velocity vector maps were shown. The vortex trace and the vortex intensity distribution were also illustrated. As a result, a large difference on the pressure - flow-rate characteristics did not exist for three tip clearance sizes. In case of TC=4mm, the tip leakage vortex was outflow to downstream of rotor was not confirmed at the small and reference flow-rate conditions. Only at the large flow-rate condition, its outflow to downstream of rotor existed. In case of TC=2mm, overall vortex behaviors were almost the same ones in case of TC=4mm. However, the vortex trace inclined toward more tangential direction. In case of TC=1mm, the clear vortex was not observed for all flow-rate conditions.

• 동력기계공학회지
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• 제20권6호
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• pp.64-70
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• 2016

The unsteady-state, incompressible and three-dimensional large-eddy simulation(LES) was carried out to evaluate the vorticity distribution of a small-size axial fan(SSAF). The X-component vorticity profiles developed around blade tips turn from axial to radial, and diminish the density of distribution according to the increase of static pressure. Otherwise, the Z-component vorticity profiles evenly develop at the region larger than the half radial distance of blade at the operating points of A and B, partly at the trailing-edge region of blade and radially over bellmouth according to the increase of static pressure.

• 설비공학논문집
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• 제14권11호
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• pp.954-963
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• 2002

For the optimal design of an automotive blower system, effects of the scroll cut-off starting angle, the clearance between blade tip and bellmouth, and the scroll expansion angle on the performance of sirocco fan are investigated experimentally. Best performance is achieved at fan exposure ratio $\Deltae/r_c$,/TEX> =1.0, and clearance ratio $\DeltaeC/C=0.62. Flow characteristics inside sirocco fan are also studied by using LDV. Flow patterns in the inside of fan can be classified into three regions. Velocity vector has the same direction as rotational direction of fan at 0~$120^{\circ}$, toward the fan blades at 150～$180^{\circ}$, and opposite direction at 210~$330^{\circ}$. Turbulent intensity is relatively high near the cut-off edge in the scroll housing.