• Title, Summary, Keyword: Flow Noise

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Reduction of the Refrigerant-Induced Noise from the Transition of Flow Pattern by Decreasing Tube Diameter

  • Takushima, Akira;Han, Hyung-Suk;Jung, Wei-Bong
    • International Journal of Air-Conditioning and Refrigeration
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    • v.17 no.2
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    • pp.37-44
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    • 2009
  • It is well known that a refrigerant-induced noise is caused by two-phase flow in the indoor unit of a heat pump air-conditioner. Especially when the flow pattern in a pipe is intermittent flow, the irregular noise occurs frequently. But it is very difficult to avoid this kind of the noise for the application of air-conditioner. Therefore, in this research, the flow patterns at two-phase flow state in a pipe of the indoor unit for the air-conditioner are researched using cycle simulator at typical cycle conditions. In order to find the relationship between refrigerant-induced noise and flow pattern, the noise patterns are investigated with respect to the estimated flow pattern from the various flow pattern maps. Base on the estimations of the flow patterns by those maps, the refrigerant-induced noise is evaluated as decreasing tube diameter, which can transit the flow pattern from slug to annular flow.

Numerical study on the machine room axial flow fan of a refrigerator (냉장고 기계실 축류홴 소음의 수치적 연구)

  • Jeon, Wan-Ho;Kim, Wook;Shin, Dae-Sig;Kim, Hyun-Joo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1002-1006
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    • 2006
  • The noise of a refrigerator is consisted of the various flow noises of a refrigerator fan, a compressor and a condenser fan. The demands of high flow rate, compact space and low noise are to be accommodated, especially, in the case of a premium refrigerator. In this study, flow field, noise sources and flow noise are analyzed numerically and compared to the measured data. The flow field is calculated with 3-dimensional CFD solver - SC/Tetra, and the noise source and aeroacoustic noise is analyzed with FlowNoise S/W. Low noise axial fan can be developed by controlling the dominant noise source area.

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Prediction of Two-phase Flow Patterns and Noise Evaluation for Evaporator Pipe in a Refrigerator (냉장고 증발기 배관의 2상유동양식 예측 및 소음 평가)

  • Heo, So-Jung;Kim, Min-Seong;Han, Hyung-Suk;Jeong, Weui-Bong
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.21 no.10
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    • pp.916-923
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    • 2011
  • The refrigerant after the expansion valve interchanges the heat at the evaporator. At this moment, the state of gas and liquid becomes two-phase flow and causes irregular noise. In order to avoid the noise, the two-phase flow pattern should be predicted. In this paper, the procedure to predict the two-phase flow patterns such as churn flow and annular flow was suggested using the CFD software. The experiments using refrigerant-supplying equipment was carried out and the noise levels according to the flow pattern were measured. The flow patterns predicted by this procedure showed good agreement with those by experiments. The churn flow is noisier than annular flow pattern.

A Study on the Noise Reduction of Construction Equipment's Muffler with the High Velocity Flow (유동소음을 고려한 건설장비용 머플러의 저소음화 연구)

  • Kim, Hyung-Taek;Joo, Won-Ho;Bae, Jong-Gug
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.802-805
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    • 2007
  • The exhaust system, including a muffler, is one of the major sources to generate the radiated noise of construction equipment. The muffler is generally known that it reduces the exhaust noise level, but it sometimes increases the noise level because of the flow effect inside a muffler. So, it is required to consider the flow effect inside a muffler to reduce the exhaust noise level of construction equipment. In this paper, an experimental method to consider a quantitative flow effect inside a muffler was set up through a series of tests. Finally, the experimental result was verified through the flow noise analysis using CFD analysis result. These results make it possible to understand the dynamic characteristics of the flow noise and to design the low noise muffler for the construction equipment.

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An Experimental Study for Noise Reduction of the Cross-Flow Fan of the Room Air-Conditioners

  • Koo, Hyoung-Mo
    • International Journal of Air-Conditioning and Refrigeration
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    • v.8 no.2
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    • pp.89-100
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    • 2000
  • Present study explains some experimental results on the aerodynamic noise of the cross-flow fan usually installed in the indoor unit of the room air-conditioners and provides a simple reduction method of radiating sound to decrease the total noise level. The spectra of the noise of the cross-flow fan were analyzed by the spectral decomposition method to characterize the generated sound. The unsteady fluctuating flow field was also measured using the I-type hot-wire probe. Comparing the spectral characteristics of the sound and the flow velocity, a useful noise reduction method was proposed, which bounds the region with a fence where the flow fluctuations were noticeably changed in the same fashion as the source spectral distribution functions vary. To validate the proposed method for reducing noise generated by the cross-flow fan, the sound pressure levels of the cross-flow fan system were compared with and without the bounding fence for various flow rates.

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Reduction of Flow-Induced Noise in Suction Nozzle of a Vacuum Cleaner by Adopting a Cross-Flow Fan (횡류팬을 적용한 진공청소기 흡입노즐내 유동 소음 저감에 관한 연구)

  • Park, I-Sun;Sohn, Chae-Hoon;Lee, Sung-Cheol;Oh, Jang-Keun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.935-938
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    • 2007
  • In suction nozzle of a vacuum cleaner, where flow-induced noise is generated mainly by flow resistance, several ideas to reduce noise are investigated. To increase fan performance, blade number is optimized and a centrifugal fan is replaced by a cross-flow fan, In addition, gear ratio of fan to drum brush is changed. It is found that fan performance is increased by adopting these methods. Next, the blade height of the fan is decreased to reduce sound pressure level, which causes inevitably decrease in fan performance. Eventually, flow-induced noise is reduced by 6.3 dBA in its overall level with the fan performance maintained.

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Fan Noise Prediction Method of Air Conditioning and Cooling System (공기조화 및 냉각시스템의 팬 소음예측 기법)

  • Lee, Jin-Young;Lee, Chan;Kil, Hyun-Gwon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1318-1320
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    • 2007
  • Fan noise prediction method is presented for air conditioning and/or cooling system applications where fan acts as an internal equipment having very complicated flow interaction with other various system components. The internal flow paths and distribution in the fan-applied systems such as computer or air conditioner are analyzed by using the FNM(Flow Network Modeling) with the flow resistances for flow elements of the system. Based on the fan operation point predicted from the FNM analysis results, the present fan noise model predicts overall sound power, pressure levels and spectrum. The predictions of the flow distribution, the fan operation and the noise level in electronic system by the present method are well agreed with 3-D CFD and actual noise test results.

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Analysis on Performance of Axial Flow Fan for Outdoor Unit of Air-conditioner: Noise Characteristics (에어컨 실외기용 축류홴의 성능에 관한 연구: 소음 특성)

  • Kim, Yong-Hwan;Lee, Jang-Ho
    • The KSFM Journal of Fluid Machinery
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    • v.13 no.5
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    • pp.29-34
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    • 2010
  • In this paper, aerodynamic noise of axial flow fans for outdoor unit of air-conditioner was analyzed by both experiment and numerical simulation. The three-dimensional incompressible turbulent flow was predicted by the commercial computational fluid dynamics code SC/Tetra, while the aeroacoustic noise of an axial flow fan was predicted by FlowNoise. Computations and experiments were performed with two types of axial flow fans, in which very different noise source distributions were presented. The results obtained from this study are expected to show the way to reduce the noise of axial flow fans in industrial applications.

Numerical Analysis of Flow-Induced Noise in Suction Nozzle of a Vacuum Cleaner with a Rotary Fan (팬이 장착된 진공청소기 흡입 노즐내 유로 유동 소음해석)

  • Park, I-Sun;Lee, Sung-Cheol;Oh, Jang-Keun;Sohn, Chae-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.208-211
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    • 2006
  • Flow resistance induced by each element in suction nozzle of a vacuum cleaner with a rotary fan is investigated numerically and its relation with flow-induced noise is examined. Flow resistance and vorticity in suction nozzle are calculated and it is found that they are closely related with flow-induced noise. From numerical results, it is suggested that reduction of flow resistance effectively increases all-suction performance and decreases sound pressure level of noise generated in the suction nozzle.

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Numerical Analysis of Flow-Induced Noise and Fan Performance in Suction Nozzle of a Vacuum Cleaner with a Double-Blade Fan (이중 블레이드 팬이 장착된 진공청소기 흡입 노즐내 유로 유동 소음 및 팬 성능 해석)

  • Park, I-Sun;Sohn, Chae-Hoon;Lee, Sung-Cheol;Oh, Jang-Keun
    • Proceedings of the KSME Conference
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    • pp.2632-2637
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    • 2007
  • Rotary performance and flow resistance induced by each element in suction nozzle of a vacuum cleaner with a double-blade rotary fan are investigated numerically and its relation with flow-induced noise and rotary performance is examined. Flow resistance and vorticity in suction nozzle are calculated and it is found that they are closely related with flow-induced noise. Gap between double blades, adoption of cross-flow fan, enlargement of flow inlet area, and optimization of blade number are tested for noise reduction. Finally, the effects of each method are verified experimentally. It is found that several combinations of the proposed methods can be adopted for noise reduction although the degree of reduction is not much.

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