• Title, Summary, Keyword: Aerodynamic Noise

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Measurement and Prediction of Aerodynamic Noise from Sirocco Fans (시로코 홴 성능 및 공력 소음 예측에 관한 연구)

  • Kim, Kyoung-Ho;Park, Kye-Chan;Lee, Seungbae
    • The KSFM Journal of Fluid Machinery
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    • v.2 no.4
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    • pp.57-64
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    • 1999
  • The prediction method of the performance and aerodynamic noise from a sirocco fan was developed and compared with measured data. To predict the performance of the sirocco fan, the well-known slip coefficients and various loss models were tested and applied to forward curved sirocco impellers. Using loss models proposed for both impeller and casing, the predicted performance characteristics were in good agreement with measured ones by an ANSI test plenum. Various scaling models for aerodynamic noise from the sirocco fan were evaluated and tested against measured power levels in terms of flow coefficient. It was shown that the turbulent broadband sound power from the sirocco fan can be modeled successfully by trailing edge noise.

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Design Program of Low Noise Centrifugal Fans (저소음 원심형 홴의 설계 프로그램)

  • 박준철;손정민;김기황;이승배
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.529-535
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    • 2001
  • A centrifugal fan design code was developed and packaged together with iDesignFan/sup TM/ as new models. This code generate centrifugal forward curved and backward curved bladed impeller optimally. It also predicts the aerodynamic performance and the overall sound pressure level of the rotating fan by assuming steady blade loading. The overall sound pressure level is used as an input parameter from the third loop of the designing process to acquire the most silent fan for the given aerodynamic performance parameters. With this kind of inverse design concept used in the code, the period of designing a fan is significantly shortened. A centrifugal fan design code, developed in this study and included in iDesignFan/sup TM/, predicts the aerodynamic performance such as design flow rate and static pressure. The aerodynamic performance in the design and off-design conditions is calculated by using the mean line analysis. For the steady loading calculation, the lift force distribution in a blade is used.

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Analysis on Wayside Noise Generated by Korean Train Express (한국형 고속철도에서 방사되는 소음분석)

  • 김재철;구동회;문경호
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.12 no.9
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    • pp.668-673
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    • 2002
  • The sources of wayside noise for the high -speed train are the aerodynamic noise, rolling noise and power unit noise. We should know the major source to control noise radiated from train. In this paper, we present the test results on the wayside noise and the vibration of the rail/sleeper during the passing of Korean Train Express (KTX). It turns out that the major noise sources for KTX are the rolling noise and power unit noise at 300 km/h. Generally, the noise attenuation with distance is independent of train speed. However, the test results show that in the near field the noise levels decrease by about 5~6 ㏈(A) per doubling of distance at speed in the range of 50~120 km/h and about 3~4 ㏈(A)/d.d at 300 km/h.

High Speed Rail : Prediction of Aerodynamic Noise (고속철도소음예측 : 공력소음의 속도민감성)

  • Kim, Jeung-Tae;Kim, Jung-Soo;Kim, Suk-Hyun
    • Proceedings of the KSR Conference
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    • pp.101-106
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    • 2007
  • Noise pollution from a high speed train has been a serious social issue nowadays. Especially when a train speed exceeds 300km/hr, an aerodynamic noise level has been known to be increased based on 4-6th power laws. In this paper, a simple approach to evaluate the sensitivity effect on noise due to the speed change has been examination.

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A Study on the Noise Property and Its Reduction of the FCEV Blower (FCEV 블로워의 소음특성과 개선방향에 관한 연구)

  • Oh, Ki-Seok;Lee, Sang-Kwon;Seo, Sang-Hoon
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.18 no.5
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    • pp.516-523
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    • 2008
  • Centrifugal turbo blower is requested highly efficiency and low noise in FCEV, but the noise generated by this machine causes of the most serious problems in the NVH performance. In general, centrifugal turbo blower is dominated by mechanical noise and aerodynamic noise. Mechanical noise is generated by rotation of the bearing, misalignment and unbalance. And aerodynamic noise is generated by the strong intersection between the flow discharged from the impeller and the cut-off in the casing. The first object of this study is to comprehend a noise property of the blower through the noise test. And, second object is to bring up the method that can reduce blower noise.

A Study on the Noise Property and its Reduction of the FCEV Blower (FCEV 블로워의 소음특성과 개선방향에 관한 연구)

  • Oh, Ki-Seok;Lee, Sang-Kwon;Seo, Sang-Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.1419-1424
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    • 2007
  • Centrifugal turbo blower is requested highly efficiency and low noise in FCEV, but the noise generated by this machine causes of the most serious problems in the NVH performance. In general, centrifugal turbo blower is dominated by mechanical noise and aerodynamic noise. Mechanical noise is generated by rotation of the bearing, misalignment and unbalance. And aerodynamic noise is generated by the strong intersection between the flow discharged from the impeller and the cut-off in the casing. The first object of this study is to comprehend a noise property of the blower through the noise test. And, second object is to bring up the method that can reduce blower noise.

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Sunroof Wind Noise Reduction Using Automatic Noise Measurement and Analysis System (자동 소음 계측 및 분석 장치를 이용한 자동차 썬루프 윈드노이즈 저감 기술 개발)

  • Shin, Seong-Ryong;Kim, Heung-Ki;Jung, Seung-Gyoon;Kook, Hyung-Seok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.166-169
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    • 2005
  • The best sunroof wind noise quality is mainly related to the sunroof deflector which affects both low-speed buffeting and high-speed aerodynamic noise. An automatic deflector-moving and noise-measuring apparatus is developed to obtain hundreds of measuring data which haven't been available by hand. With an additional program for fast and easy noise analysis, this device leads quickly to the better position and angle of the deflector. Now, the 'better' means the lower noise level and the robuster design solution. From these kinds of better solutions, more meaningful guidelines on the deflector design and sunroof wind noise reduction can be suggested.

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Aerodynamic Performance Enhancement and Noise of Cooling Fans for Driving Motor (전동차용 모터 냉각홴의 공력성능 향상 및 소음특성)

  • Kang, Shin-Hyoung;Park, Tae-Choon;Cho, Nam-Hyo
    • The KSFM Journal of Fluid Machinery
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    • v.1 no.1
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    • pp.32-40
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    • 1998
  • Aerodynamic performance of a cooling fan of driving motor was enhanced modifying the vane-shroud configuration. Performance of a target model was evaluated to obtain baseline data. The aerodynamic performance and sound pressure level were tested and measured with different numbers of vane of increased length. The tested models show high and stable performance and low values of specific noise level. The long vane-shroud structure induces more stable through flow and decreases the tip leakage flow, which contributes to the increases of performance and efficiency. The sound pressure level increases for the modified model, however, specific noise level decreases.

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Aero-Induced Vibration Analysis of a Rotating Disk using a Vacuum Chamber (진공 실험을 통한 공기와 회전 디스크의 상호 작용 및 진동 특성)

  • 이승엽;윤동화;박영필
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.677-683
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    • 2002
  • The analytical and experimental studies on aerodynamic flutter instability of rotating disks in information storage devices are investigated. The theoretical analysis uses a fluid-structure model where the aerodynamic force on the rotating disk is represented in terms of lift and damping forces. Based on the analytical approach, it is shown that the backward natural frequency of the disk is equal to that of the case without aerodynamic effect at the flutter onset speed. In post-flutter regions, the natural frequencies are larger than those in vacuum conditions without aerodynamic effect. The analytical predictions on the natural frequencies of rotating disks with/without aerodynamic effect are experimentally verified using a vacuum chamber and ASMO optical disks.

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Numerical Analysis of 2-Dimensional Viscous Compressible Flow around the High Speed Train (고속열차 주위의 점성 압축성 2차원 유동해석)

  • Ha, Seong-Do;Kim, Yu-Il
    • 연구논문집
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    • pp.13-22
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    • 1995
  • At the running speed higher than 250 km/h, several aerodynamic problems such as the increase of aerodynamic resistance, aerodynamic noise, pressure fluctuation at the tunnel entry, impulsive wave at the tunnel exit bring about the power consumption, deterioration of riding quality, and severe environmental noise. To solve these aerodynamic problems, the flow phenomena around the high speed train have to be analyzed in detail. In this study, the flow around the train is modelled as the 2-dimensional viscous compressible flow and the flow field is calculated numerically for the three different types of geometry and running speed. The aerodynamic drag coefficient and the pressure coefficient are evaluated each case.

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