Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
권호 표지
DOI QR코드

DOI QR Code

Investigation of Skin Friction Reduction Mechanism of Outer-Layer Vertical Blades Using POD Analysis

POD 기법을 이용한 경계층 외부 수직날의 마찰저항 저감 기구에 관한 관측

  • An, Nam Hyun (Dept. of Shipbuilding and Marine Engineering, Koje College) ;
  • Park, Seong Hyeon (Dept. of Naval Architecture and Ocean Engineering, Pusan Nat'l Univ.) ;
  • Chun, Ho Hwan (Dept. of Naval Architecture and Ocean Engineering, Pusan Nat'l Univ.) ;
  • Lee, Inwon (Global Core Research Center for Ships and Offshore Plants, Pusan Nat'l Univ.)
  • 안남현 (거제대학교 조선해양공학과) ;
  • 박성현 (부산대학교 조선해양공학과) ;
  • 전호환 (부산대학교 조선해양공학과) ;
  • 이인원 (부산대학교 조선해양플랜트 글로벌핵심연구센터)
  • Received : 2012.11.16
  • Accepted : 2013.04.08
  • Published : 2013.06.01
Download PDF
⟨ Previous Next ⟩

Abstract

A POD analysis based on time-resolved PIV measurements in a circulating water channel has been conducted to identify the skin friction reduction mechanism of outer-layer vertical blades. A recent PIV measurement indicated 2.73% and 7.95% drag reduction in the blade plane and the blade-in-between plane, respectively. In the present study, the influence of vertical blades array upon the characteristics of the turbulent coherent structures was analyzed by the POD method. It is observed that the vortical structures are cut and deformed by the blades array and that their temporal evolution is strongly associated with the skin-friction drag reduction mechanism in the turbulent boundary layer flow.

외부경계층 수직 날의 마찰저항 저감 기구를 규명하기 위하여 회류수조에서 시간분해 입자영상유속계로 측정된 비정상 유동장에 POD 분석을 실시하였다. 최근의 PIV 결과에서는 수직날 평면 및 수직날 사이 평면에서 각각 2.73%, 7.95%의 마찰저항 저감효과가 발견되었다. 본 연구에서는 수직날 배열이 난류조직구조에 미치는 영향을 POD 방법을 통하여 분석하였다. 난류유동의 조직적인 와구조가 수직날에 의하여 절단, 변형되고 비정상 거동이 난류경계층에서의 마찰저항 저감 기구와 밀접하게 관련된 것으로 관찰되었다.

Keywords

References

  1. Schoppa, W. and Hussain, F., 1998, "Genesis of Longitudinal Vortices in Near-Wall Turbulence," Meccanica, Vol. 33, pp.489-501. https://doi.org/10.1023/A:1004320610285
  2. Hutchins, N., 2003, "An Investigation of Larger-Scale Coherent Structures in Fully Developed Turbulent Boundary Layers," Ph.D. Thesis, University of Nottingham.
  3. Park, H., An, N. H., Hutchins, N., Choi, K-S., Chun, H. H. and Lee, I., 2011, "Experimental Investigation on the Drag Reducing Efficiency of the Outer-Layer Vertical Blades," Journal of Marine Science Technology, Vol. 16, pp. 390-401. https://doi.org/10.1007/s00773-011-0135-0
  4. Beckert, D. W. and Bartenwerfer, M., 1989, "The Viscous Flow on Surfaces with Longitudinal Ribs," Journal of Fluid Mechanics, Vol. 206, pp.105-129. https://doi.org/10.1017/S0022112089002247
  5. Park, H., An, N. H., Park, S. H., Chun, H. H. and Lee, I., 2011, "PIV Investigation on the Skin Friction Reduction Mechanism of Outer-Layer Vertical Blades," Journal of the Korean Society of Visualization, Vol. 9, pp. 20-28. https://doi.org/10.5407/JKSV.2011.9.1.020
  6. Karhunen, K., 1946, "Zur Spectral Theorie Stochasticher Prozesse," Annales Academiae Scientiarum Fennicae Series A, Vol.1, p.34.
  7. Berkooz, G., Holmes, P. and Lumley, J., 1993, "The Proper Orthogonal Decomposition in the Analysis of Turbulent Flows," Annual Review of Fluid Mechanics, Vol.25, pp.539-575. https://doi.org/10.1146/annurev.fl.25.010193.002543
  8. Sirovich, L., 1987, "Turbulence and the Dynamics of Coherent Structures," Quarterly of Applied Mathematics, Vol. 45, No. 3, pp.561-590. https://doi.org/10.1090/qam/910462
  9. Adrian, R. J., Meinhart, C. D. and Tomkins, C. D., 2000, "Vortex Organization in the Turbulent Boundary Layer," Journal of Fluid Mechanics, Vol. 422, pp.1-54. https://doi.org/10.1017/S0022112000001580