Ecology and Resilient Infrastructure

Korean Society of Ecology and Infrastructure Engineering (응용생태공학회)
권호 표지
DOI QR코드

DOI QR Code

Measurement and Analysis of Bed Shear Stresses in Compound Open Channels using the Preston Tube

프레스톤튜브를 이용한 복단면 하도의 하상전단응력 측정 및 분석

  • Lee, Du Han (Hydro Science and Engineering Research Institute, Korea Institute of Civil Engineering and Building Technology) ;
  • Kim, Myounghwan (Hydro Science and Engineering Research Institute, Korea Institute of Civil Engineering and Building Technology) ;
  • Kim, Won (Hydro Science and Engineering Research Institute, Korea Institute of Civil Engineering and Building Technology) ;
  • Seo, Il Won (Department of Civil and Environmental Engineering, Seoul National University)
  • 이두한 (한국건설기술연구원 수자원하천연구소) ;
  • 김명환 (한국건설기술연구원 수자원하천연구소) ;
  • 김원 (한국건설기술연구원 수자원하천연구소) ;
  • 서일원 (서울대학교 건설환경공학부)
  • Received : 2017.11.15
  • Accepted : 2017.12.11
  • Published : 2017.12.31
Download PDF
⟨ Previous Next ⟩

Abstract

Hydraulic issues such as flow resistance, side wall correction, sediment, erosion and deposition, and channel design have close relation with distribution of bed shear stresses but the measurement of the distribution of bed shear stresses is not easy. In this study the Preston tube which makes possible relatively simple measurement of bed shear stresses is used to analyze the characteristics of bed shear distribution in compound open channels with different depth ratio. The Preston tubes are made and calibrated to develop the calibration formula and then they are applied to measure bed shear stress distribution in 5 cases depth ratio condition of compound channels. The results are compared with former experiment data, and characteristics of bed shear stress distributions are studied with different channel scales and Reynolds numbers. Although bed shear distributions with depth ratio show overall agreement with former studies, some differences are verified in bed shear variation, formation of inflection point in main channel, and distribution near floodplain junction which are due to high Reynolds number. Through the study applicability of the Preston tubes are also verified and characteristics of bed shear distribution in compound channels are suggested with Reynolds number and depth ratio.

하도의 흐름 저항, 측벽 보정, 유사량, 하도 침식과 퇴적, 하도 설계 등의 수리학적 문제는 하상전단응력의 분포와 밀접한 관계가 있으나 하상전단응력 분포를 측정하는 것은 쉽지 않다. 본 연구에서는 간편하게 하상전단응력을 측정할 수 있는 프레스톤튜브를 이용하여 복단면의 하도의 하상전단응력 분포를 측정하고 수심비에 따른 전단응력분포 특성을 고찰하였다. 이를 위해 프레스톤튜브를 제작하여 검정실험을 통해 검정식을 개발하였다. 실험은 5가지 수심비 조건에 대해서 수행하여 전단응력분포를 측정하였다. 복단면 하도의 전단응력분포 특성은 기존 실험연구와 대체로 일치하였으며, 레이놀즈수 증가로 발생하는 전단응력의 변동성, 주수로 전단응력의 변곡점 형성, 홍수터 접합부 부근 전단응력 분포 특성 등에서 차이점을 확인하였다. 본 연구를 통해 프레스톤튜브를 이용한 하상전단응력측정 적용성을 확인하였으며 레이놀즈수와 수심비에 따른 복단면 하도의 전단응력분포 특성을 제시하였다.

Keywords

References

  1. Gessner, F.B. 1973. The origin of secondary flow in turbulent flow along a corner. Journal of Fluid Mechanics 58(1): 1-25. https://doi.org/10.1017/S0022112073002090
  2. Guo, J. and Julien, P.Y. 2005. Shear stress in smooth rectangular open-channel flows. Journal of Hydraulic Engineering 131(1): 30-37. https://doi.org/10.1061/(ASCE)0733-9429(2005)131:1(30)
  3. Haritonidis, J. 1989. The measurements of wall-shear stress. Advances in Fluid Mechanics Measurements, pages 229-261.
  4. Heinz, M. 2002. Investigation of Bendway Weir Spacing. Master's Thesis, Colorado State University, Department of Civil and Environmental Engineering, Fort Collins, Colorado.
  5. Hsu, E.Y. 1955. The Measurement of Local Turbulent Skin Friction by Means of Surface Pitot Tubes." David W. Taylor Model Basin, Report No. 957, August.
  6. Ippen, A.T., Drinker, P.A., Jobin, W.R., and Noutsopoulos, G.K. 1960. The Distribution of Boundary Shear Stresses in Curved Trapezoidal Channels. Department of Civil and Sanitary Engineering, Massachusetts Institute of Technology, Technical Report No. 43, October.
  7. Knight, D.W., Demetriou, J.D. and Hamed, M.E. 1983. Boundary shear in smooth rectangular channels. Journal of Hydraulic Engineering, ASCE 110(4): 405-422. https://doi.org/10.1061/(ASCE)0733-9429(1984)110:4(405)
  8. Ludweig, H., and Tillman, W. 1950. Investigations of the Wall-Shearing Stress in Turbulent Boundary Layers. National Advisory Committee for Aeronautics, Technical Memorandum 1285, May.
  9. Preston, J. H. 1954. The Determination of Turbulent Skin Friction by Means of Pitot Tubes. Journal of the Royal Aeronautical Society, Vol. 58: 109-121. https://doi.org/10.1017/S0368393100097704
  10. Rajarantnam, N., and Ahmadi, R. M. 1981. Hydraulics of channels with floodplains. J. Hydr. Res. 19(1): 43-60. https://doi.org/10.1080/00221688109499530
  11. Thornton, C.I., Cox, A.L., and Sclafani, P. 2008. Preston Tube Calibration. Colorad State University Engineering Research Center, Fort Collins, Colorado.
  12. Tominaga, A. and Nezu, I. 1991. Turbulent structure in compound open channel flows. Journal of Hydraulic Engineering 117(1): 21-41. https://doi.org/10.1061/(ASCE)0733-9429(1991)117:1(21)
  13. Tominaga, A., Nezu, I., Ezaki, K. and Nakagawa, H. 1989. Three-dimensional turbulent structure in straight open channel flows. Journal of Hydraulic Research 27(1): 149-173. https://doi.org/10.1080/00221688909499249
  14. Yang, S.Q. and Lim, S.Y. 1997. Mechanism of energy transportation and turbulent flow in a 3D channel. Journal of Hydraulic Engineering, ASCE 123(8): 684-692. https://doi.org/10.1061/(ASCE)0733-9429(1997)123:8(684)