• 대한기계학회논문집B
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• 제27권12호
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• pp.1655-1666
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• 2003

It is experimentally well-known that high anisotropies of the turbulent flow field are dominant inside the tip leakage vortex, which is attributable to a substantial proportion of the total loss and constitutes one of the dominant mechanisms of the noise generation. This anisotropic nature of turbulence invalidates the use of the conventional isotropic eddy viscosity turbulence models based on the Boussinesq assumption. In this study, to check whether an anisotropic turbulence model is superior to the isotropic ones or not, the results obtained from the steady-state Reynolds averaged Navier-Stokes simulations based on the RNG k-$\varepsilon$ model and the Reynolds stress model (RSM) are compared with experimental data for two test cases: a linear compressor cascade and a forward-swept axial-flow fan. Through this comparative study of turbulence models, it is clearly shown that the RSM, which can express the production term and body-force term induced by system rotation without introducing any modeling, should be used to predict quantitatively the complex tip leakage flow, especially in the rotating environment.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 춘계학술대회논문집
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• pp.1140-1145
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• 2003

In this paper, some dominant aeroacoustic characteristics of fans used in appliances are reviewed. The numerical attempts to analyze tile aeroacoustic noise of fans are briefly reviewed for various fans. Axial fans for refrigerator, cross flow fans fer air-conditioner, sirocco fans and turbo fans are anal: zed. The unsteady flow field, which is essential data for aeroacoustic analysis, is calculated by commercial CFD code. Acoustic pressure is calculated by Ffowcs Williams and Hawkings equation and Lowson's equation. During the analysis, dominant noise sources are identified.

• 한국음향학회지
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• 제36권6호
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• pp.371-377
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• 2017

에어컨의 성능은 분리형 실외기의 냉각 성능과 밀접한 관련이 있으며, 그에 따라 대다수의 관련 선행 연구에서는 실외기 내부 축류팬의 단독 성능에 대한 연구를 진행하였다. 하지만 축류팬을 제외한 실외기 내부 여러 구성요소의 영향에 대한 연구는 부족한 실정이다. 따라서 본 논문에서는 여러 요소 중 팬 오리피스가 실외기 유동 성능에 미치는 영향을 수치적으로 분석하였다. 고정밀 유동장 해석을 위해 약 1800만 개의 격자로 구성된 가상 팬 테스터를 개발하고, V-LES의 일종인 비정상 RANS(Reynolds-averaged Navier-Stokes) 방정식을 CFD(Computational Fluid Dynamics) 기법에 기초하여 해석하였다. 수치 해석의 유효성을 확인하기 위해서 실험을 통해 측정한 실외기 시스템의 P-Q 곡선을 가상 팬 테스터를 사용한 수치 해석 결과와 비교하였다. 유효성을 검증한 수치 기법을 이용하여 실외기 유량 성능을 최대화할 수 있는 오리피스 형상 최적 설계를 수행하였다.

• 한국음향학회지
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• 제12권6호
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• pp.28-35
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• 1993

팬소음은 설계변수들과 관계가 있으므로 본 논문은 실험적 방버벵 의하여 팬소음과 설계변수의 관계를 고찰하였다. 설계변수는 팬소음에 특히 영향이 큰 날개수, 날개각도, 날개끝 간극을 선택하였으며 새로운 설계변수로서 동익과 정익간의 간극과 흡입구 길이를 고찰하였다. 본 논문은 팬소음에 대한 관련된 이론을 정리하였으며 축류형 팬의 고효율 저소음 설계를 위한 방안을 제시하였다. 흡입구 길이, 날개끝 간극, 동익과 정익간의 간극등의 설계변소를 변경하여 실험한 결과 이들 설계변수들의 조정에 m이하여 축류형 팬의 고효율 저소음화를 이룰 수 있었다.

• 한국소음진동공학회논문집
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• 제13권4호
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• pp.258-265
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• 2003

This paper suggests the noise reduction method of the engine cooling fan. The fan noise contribution to the OASPL of engine room was estimated and the noise source was identified for the rotating fan by sound intensity method. And the program for Predicting the noise spectrum of axial flow fan was also developed. The radiated acoustic pressure is expressed in terms of discrete frequency noise Peaks at BPF and its harmonics and the line spectrum at the broad band by the proposed noise generation mechanisms. In this Paper, it Is shown that the comparison of the measured and calculated noise spectra of fan validates the noise predicting program. And this paper presents the characteristics of the fan noise in order to modify the design parameters. Accordingly, the design parameters were determined for the noise reduction of the fan.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문집
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• pp.279-284
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• 2002

In this study, it has been developed the program for predicting the noise spectrum of axial flow fan. The radiated acoustic pressure is expressed the discrete frequency noise peaks at BPF(Blade passage frequency) and its harmonics by Wu's method and the line spectrum at the broad band by Wright's method. And this paper presents the characteristics of a fan noise due to modify the design parameters. Accordingly, it is obtained the design parameter values for noise reduction of fan.

• 한국산업융합학회 논문집
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• 제23권1호
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• pp.101-106
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• 2020

Along with dust collection efficiency, pressure loss is a very important cyclone operation factor. A severe rise in pressure loss causes the problem of cost. To solve the problem, the method connecting axial-vane type cyclones in parallel is suggested recently. The axial vane type cyclone dust collector applied in this study is a small portable type. Multiple cyclones are installed in a round type. The basic performance test on the axial vane type cyclone dust collector was conducted. As a result, the cut size reduced along with a rise in the wind velocity of the cyclone dust collector inlet. According to the test on dust collection efficiency, the effect of dust collection began to appear in the range of 3㎛ and dust collection efficiency was greatly improved at 5 ㎛. The noise of the cyclone dust collector well met the fan sound power level of KSB 6361.

• 한국유체기계학회 논문집
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• 제7권2호
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• pp.7-13
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• 2004

In an attempt to solve multiobjective optimization problems, weighted sum method is most widely used for the advantage that a designer can consider the relative significance of each object functions by weight values but it can be highly sensitive to weight vector and occasionally yield a deviated optimum from the relative weighting values designer designated because the multiobjective function has the form of simple sum of the product of the weighting values and the object functions in traditional approach. To search the design solution agree well to the designer's weighting values, we proposed new multiobjective function which was the functional of each normalized objective functions and considered to find the design solution comparing the distance between the characteristic line and the ideal optimum. In this study, proposed multiobjective function was applied to design high efficiency and low noise axial flow fan and the result shows this approach is effective for the case that the quality of the design can be highly affected by the designer's subjectiveness represented as weighting values in multiobjective design optimization process.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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• pp.397-403
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• 2003

In an attempt to solve multiobjective optimization problems, weighted sum method is most widely used for the advantage that a designer can consider the relative significance of each object functions by weight values but it can be highly sensitive to weight vector and occasionally yield a deviated optimum from the relative weighting values designer designated because the multiobjective function has the form of simple sum of the product of the weighting values and the object functions in traditional approach. To search the design solution well agree to the designer's weighting values, we proposed new multiobjective function which is the functional of each normalized objective functions and considered to find the design solution comparing the distance between the characteristic line and the ideal optimum. In this study, proposed multiobjective function was applied to design high efficiency and low noise axial flow fan and the result shows this approach will be effective for the case that the qualify of the design can be highly affected by the designer's subjectiveness represented as weighting values in multiobjective design optimization process.

• 한국축산시설환경학회지
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• 제13권2호
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• pp.105-112
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• 2007

본 연구는 축산 농가에 적용할 광역방제기를 개발하는데 있어 선행되어야 할 팬의 성능을 실험하고 분석하는데 목적이 있다. 연구에 사용된 방제기 팬은 최고 살포거리가 140m이고 유효 살포거리가 100 m가 되도록 설계 및 제작되었다. 따라서, 멀리 살포될 수 있도록 설계된 팬의 풍량은 $3,600\;m^3/min$, 정압은 100 mmAq로 하였다. 이러한 팬의 성능을 측정하고 분석하기 위하여 덕트를 이용한 풍동실험장치를 구성하였다. 본 실험에 앞서, 풍량 $600\;m^3/min$, 전압 500 mmAq을 요하는 팬을 이용하여 기초 실험으로 수행하였다. 덕트 끝단에 설치된 스로틀 밸브를 통하여 풍량을 조절하며, 송풍출구와 정류격자 사이에 설치된 피토관을 이용하여 전압과 정압을 측정하였다. 풍량은 5개의 구간으로 나누고, 각 풍량에서 덕트 단면 내의 10개 지점에서 피토관 측정을 하였다. 이렇게 풍동실험을 통해 나온 결과를 예측된 결과와 비교하여 방제기 팬의 성능을 분석하였다. 측정 결과 풍량에 따른 축동력은 예측한 성능곡선과 비교하였을 때 실험 팬의 최적설계사양과 같은 최소의 오차가 났으며, 동력 효율이 최대로 나타났다. 소음측정 결과는 92.1 dB로 나타나 환경기준인 85 dB에는 미달되지만 밀폐된 실험장소를 감안한다면 기준에 적합한 것으로 판단되었다.