Journal of the Korean Society for Aeronautical & Space Sciences (한국항공우주학회지)

The Korean Society for Aeronautical and Space Sciences (한국항공우주학회)
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Papers : Flow Noise due to the Impinging Vortex to the Chamfered Forward Step

논문 : 모따기 된 전향계단에 부딪치는 와류에 의한 유동소음

  • Published : 2002.02.28
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Abstract

In cavity flow, the rectangular step generates so strong sound that many researchers have investigated method to suppress the nois during interaction between vortical flow and rectangular forward step. In this study the flow noise from the vortex motion in two-dimentional low Mach number flow past a forward step with various chamfering angle is calculated numerically. Inviscid incompressible discrete vortex model and matched asymptotic expansion(MAE) theory are applied to obtain the inner flow field and the outer noise field. Both source acoustic pressure and sound intensity are obtained with various chamfering height, chamfering angle and initial vortex position. The pressure amplitude is most suppressed when the chamfering angle is between $15^{\circ}C$ and $30^{\circC}$ at the chamfering length of 30% of the step height.

공동흐름에서 직각 계단은 커다란 소음의 원인이 되어 많은 사람들의 와류와 직각계단의 상호 작용 시에 발생되는 소음의 저감 방안을 연구하여 왔다. 본 연구에서는 2차원 저아음속 와류 흐름이 전향계단을 지날 때 발생되는 유동 소음을 전향계단의 형상 변화를 통한, 즉, 계단의 모따기 양과 각도를 바꾸어 가면서 수치적으로 계산하였다. 내부 유동장을 구하기 위해서 비압축성 비점성 이산와류 모델을 가정하였으며, 유동정보로부터 원거리로의 음향장 계산은 MAE 이론을 적용하여 구하였다. 음원에서의 음압과 음압강도를 모따기 높이 및 모따기 각도와 최기 와류의 높이를 변화시켜가면서 다양하게 수치적인 결과를 얻어내었다. 본 연구를 통해서 계단에 접근하는 와류에 의한 원거리 음압은 모따기 양이 계단 높이의 30%에서 모따기 각도가 $15^{\circ}C$에서 $30^{\circ}C$°사이일 때 가장 소음이 적게 발생되는 결과를 얻어내었다.

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References

  1. Charwat, A. F., Roos, J. N., Dewey, F. C., and Hitz, J. A., "An Investigation of Separated Flows. Part I. The Pressure Field," Journal of the Aerospace Sciences, Vol. 28, Jun. 1961, pp.457-470. https://doi.org/10.2514/8.9037
  2. Rockwell, D., and Knisely, C., "The Organized Nature of Flow Impingement Upon a Corner," J. Fluid Mech. Vol. 93, 1979, pp. 413-432. https://doi.org/10.1017/S0022112079002573
  3. Rockwell, D., and Knisely, C., "Vortex-edge interaction: Mechanisms for generating low frequency components," Phys. Fluids, Vol. 23, No. 2, 1980, pp. 239-240. https://doi.org/10.1063/1.862962
  4. Ethembabaoglu, S., "On the Fluctuating Flow Characteristics in the Vicinity of Gate Slots," Division of Hydraulic Engineering, University of Trondheim, Norway, Jun. 1973.
  5. Sarno, R. L., and Franke, M. E., "Suppression of Flow-Induced Pressure Oscillations in Cavities," Journal of Aircraft, Vol. 31, No. 1, 1994, pp. 90-96. https://doi.org/10.2514/3.46459
  6. Franke, M. E., and Carr.D, L., "Effect of Geometry on Open Cavity Flow-Induced Pressure Oscillations, " AIAA Paper 75-492, AIAA 2nd Aero-Acoustics Conference, Hampton, VA, Mar. 1975, 24-26.
  7. Sarohia, V., and Massier, P. F., "Investigation of Pressure Oscillations in Axisymmetric Cavity Flows,"Harry Diamond Laboratories Report HDL-CR-77-025-1, Adelphi, Maryland, Sep. 1977.
  8. Clements, R. R., "An Inviscid Model of Two-dimensional Vortex Shedding," J. Fluid Mech. Vol. 57, 1973, pp.321-336. https://doi.org/10.1017/S0022112073001187
  9. Conlisk, A. T., and Veley, D., "The Genertion of Noise in Impinging Vortex Motion Past a Step," Phys. Fluids. Vol. 28, 1985, pp.3004-3016. https://doi.org/10.1063/1.865140
  10. Dhanak, M. R., and Gundlapalli, R., "Flow Noise due to Interaction between an Eddy and a Forward Facing Step," International Symposium on Flaw-Induced Vibration and Noise, 1992, pp.11-22.
  11. Panaras.A. G., "Pressure Pulses Generated by the Interaction of a Discrete Vortex with an Edge," J. Fluid Mech. Vol. 154, 1985, pp.445-461. https://doi.org/10.1017/S0022112085001616
  12. 김태룡, 이준신, 이선기, “고리3호기 MSIV room의 고진동/소음 현상 원인 규명, 한전 전력 연구원 TM.99NS01.P1999.138, 1999.
  13. Bernstein, M. D., and Bloomfield, W. J., "Malfunction of Safty Valves due to Flow-induced Vibration," Proceeding of flow induced Vibration, ASME, 1989, pp.155-164.