• Title/Summary/Keyword: Fan noise

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Experimental study on the design parameter effect on the noise in the cross flow fan (실험에 의한 CROSS FLOW FAN 소음 분석)

  • 안철오;류호선
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.04a
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    • pp.615-620
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    • 1997
  • The flow rate and the noise level of 18 cross flow fans were measured to analyze the effect of design variables on these and to finally find the optimal design value. These data were analyzed by the Taguchi method and the neural network. The optimal values obtained by the neural network showed good agreements with that by the Taguchi method. The effects of eight design variables on the fan performance and the noise were evaluated and discussed.

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The Analysis of Vibration characteristics for Vacuum Cleaner Fan Motor Using 3-D Laser Vibrator (3차원 레이저 진동 측정기를 이용한 초고속 진공청소기 모터의 진동특성분석)

  • 김재열;김우진;심재기;김영석
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • 2004.10a
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    • pp.399-405
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    • 2004
  • Recently technology resulted in highly efficient and multiple-functional electric appliances considering environmental problems. One of the environmental problems is noise of a product in respect to its function. A vacuum cleaner is an essential electric appliance in our daily lives. However, severe noise resulted from high motor speed for improving the function of the appliance is a nuisance for the user. This noise is caused by vibration from various parts of the appliance and fluid noise during a series of intake and exhaust processes while rotating the impeller connected to the axle at a high speed of the fan motor inside the vacuum cleaner rotating around 30,000-35,000 rpm. Despite the fact that many researchers conducted studies on reducing the noise level of the fan motor in a vacuum cleaner, only few studies have been conducted considering both the theoretical and experimental aspects using fluid analysis by measuring vibration and noise. Moreover, there has not been a study that accurately compared major noise data obtained considering both of the aspects. In this study, both aspects were considered by considering the following experimental and theoretical methods to verify the major causes of noise from the fan motor in a vacuum cleaner.

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A Numerical Study of the Effects of Design Parameter upon Fan Performance and Noise (원심홴의 설계 변수가 홴의 성능과 소음에 미치는 영향의 수치적 연구)

  • Jeon, Wan-Ho;Lee, Duck-Joo
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.3 s.4
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    • pp.45-51
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    • 1999
  • Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise due to the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan and to calculate the effects of rotating velocity, flow rate, cut-off distance and the number of blades and its effects on the noise of the fan. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated with the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The cut-off distance is the most important factor effecting the noise generation. Acoustic pressure is proportional to 2.8, which shows the same scaling index as the experimental result. In this paper, the cut-off distance is found to be the dominant parameter offecting the acoustic pressure.

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A Study on the Noise Characteristics of Cooling Tower (냉각탑의 방사소음특성에 관한 연구)

  • Park, B.Y.;Kim, I.S.;Lee, S.H.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.8 no.3
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    • pp.361-374
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    • 1996
  • In general, a cooling tower has two major noise sources, one is the fan and the other is the falling water. The fan noise is produced by passage of its blades through the air and radiates from the fan stack. Noises from the falling water are caused by splashing and dropping of water cascading over the internal filler of the cooling tower and into the basin and radiate from the louvered face. In this paper, the noise measurements and its frequency analysis are carried out for the locations facing the louvered side and near the fan stack referring the related code and standards in order to study the noise characteristics of the induced-draft cooling tower, especially for the buildings. As a result, it is found that for every doubling of distance from the noise source the noise level decreases by 2~4dBA in the near field with reflect surfaces and decreases by about 6dBA also in the far field without reflect surfaces. As a supplement to the noise measurements, a computer program with simple algorithm is developed in order to estimate the noise level at a distance from the cooling tower, so that the user could apply and modify it for the particular boundary conditions easily.

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A Study on the Flow Characteristics and Noise Predictions around the Shroud Fan using the Aero-acoustic Noise Model (공력소음 모델을 이용한 슈라우드 팬 주위의 유동특성 및 소음예측에 관한 연구)

  • Mo, Jang-Oh;Lee, Young-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.12 no.3
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    • pp.19-25
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    • 2009
  • InThe purpose of this work is to analyze the flow characteristics and aerodynamic noise generated from a shroud fan at a constant 2,100 rpm using LES and FW-H noise model provided in the commercial code, FLUENT. Velocity distributions around the shroud fan obtained by using FLUENT code show good agreement with experimental results. The sound pressure level is decreased by about 6 dB as the distance from the fan increases twice. The directivity at 1st BPF shows a tendency of increasing SPL toward the axis of rotation.

Prediction of Frequency Modulation of Discrete Noise for Random Pitch Cross-Flow Fans by Unsteady Viscous Flow Computations (비정상 점성 유동 해석에 의한 부등피치 횡류홴의 이산소음 주파수 변조 특성 예측)

  • Yong Cho;Young J. Moon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2002.11a
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    • pp.366.2-366
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    • 2002
  • Unsteady flow characteristics and associated blade tonal noise of a cross-flow fan are predicted by a computational method. The incompressible Wavier-Stokes equations are time-accurately solved for obtaining the pressure fluctuations between the rotating blades and the stabilizer, and sound pressure is predicted using Curie's equation. The computed fan performance is favorably compared with experimental data, and also indicates that the performance is not significantly altered by the random pitch effect at ø〉0.4. (omitted)

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Software Development for Fan Flow and Noise

  • 이덕주;이성규;전원주;이진욱;김영남
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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    • pp.1064-1067
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    • 2004
  • The aim of this paper is to develop a GUI based software that can predict the flow and noise generated by fan. This user-friendly software is designed for the usual fan user in the various industrial companies as well as researcher related to rotating blade:;. Software consists of 3-modules; (1) concept design and performance prediction module using simple and fast methods, (2) preliminary design and flow/noise prediction module using free-wake potential solver and acoustic analogy and (3) detail design module using accurate CFD-software and acoustic formula. Some validations and applications in various fields are described.

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Noise Reduction of Turbo Fans for Air-Conditioner Indoor Units (에어컨 실내기 터보팬의 소음 저감)

  • 김진백;최원석;구형모;이재권
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2004.05a
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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.

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Noise Reduction of a Ventilating Fan System using Micro-Perforated Panel (미세 다공판을 이용한 환기팬 시스템의 소음저감)

  • Lee, Jong-Seuk;Song, Hwa-Young;Lee, Dong-Hoon;Kwon, Hyuk-Jung;Kim, Dong-Yun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.1209-1211
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    • 2006
  • This paper introduces an experimental study for the noise reduction of a ventilating fan system. For the purpose of noise reduction, conventionally an absorptive duct silencer filled with a glass fiber has been utilized. However, a glass fiber has some disadvantages like hygiene and secondary pollution problems. In order to overcome these problems, in this paper, a perforated duct silencer has been applied to the ventilating fan system. For the designing of a perforated duct silencer, the transmission losses for various perforated panel systems are measured and compared with its noise reduction performance.

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A numerical study on the noise reduction methods of centrifugal impeller (원심형 임펠러의 저소음화에 대한 연구)

  • Jeon, Wan-Ho;Chung, Phil-Joong
    • 유체기계공업학회:학술대회논문집
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    • 2000.12a
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    • pp.129-136
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    • 2000
  • Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise because of the difficulty in obtaining detailed Information about the flow field and casing effects on noise radiation. The objective of this study is to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan, and to calculate the effects of small vanes that are attached in original impeller - Splitter impeller. We assume that the impeller rotates with a constant angular velocity and the flow field around the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. The splitter impeller changes the acoustic characteristics as well as performance. Two-splitter type impeller and splitter impeller which splitter locates in jet region are good for acoustic characteristics.

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