BibTex RIS Kaynak Göster

Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle

Yıl 2010, Cilt: 2 Sayı: 4, 83 - 92, 01.12.2010

Öz

A rectangular obstacle the front corners of which are deformed in step form (called “stepped nosed obstacle”) may experience a much smaller drag force and lift force fluctuation. The underlying physics of this drag reduction and flow stabilization mechanism are explored in numerical and theoretical approaches. In the optimal step configuration that the flow separating from the front surface edges reattaches smoothly at the leading edge of the main body’s side surface. (1) The pressure drag force acting on the forebody almost vanishes because the strong vortices trapped in the stepped corners produce the thrust force which cancel the drag force acting on the front surface, and (2) The oscillation of lift force acting on the obstacle is largely suppressed and the scale of the Karman vortices is reduced because the large scale of the separated flow over the side surface is suppressed. The step size which brings about such optimal step flow condition is identified and the dependences of various flow characteristics on the step size are discussed in detail, which will be useful to consider another drag reduction treatment than streamlining the profile of obstacle in engineering application

Kaynakça

  • [1] Kentfield, J.A.C, Short, Multi-step After Fairings, J. Aircraft, 12, 351-352, 1984.
  • [2] Koenig, K and Rosko, A., An experimental study of geometrical effects on the drag and flow field of two bluff bodies separated by a gap, J. Fluid Mech., 156, 167-204,1985.
  • [3] Morel, T., Theoretical lower limits of forebody drag, Aero. J., 83, 23-27,1979.
  • [4] Ota, T., Asano, T. and Okawa, J., Reattachment length and transition of separated flow over blunt flat plates, bulletin of the Japan Society for Mechanical Engineers, 24, 941-947, 1981.
  • [5] Prandtl, L. and Tietjens, O.G., Applied Hydro-and Aeromechanics (translated by J.P. Hartog), SS77-81, Dover; 1934.
  • [6] Ringleb, F.O., Separation Control by trapped vortices, Boundary layer, and Flow control, edited G.V. Lachmann, Pergamon, Oxford, 265-294, 1961.
  • [7] Roshko, A., On the Wake and Drag of Bluff Bodies, J. Aero. Sci.. 22, 2-** , 1955.
  • [8] Saunders, W.D., Apparatus for reducing linier and lateral wind resistance in a tractor-trailer combination vehicle, U.S. Patent No. 3241876, 1966.
  • [9] Taylor, I. and Vezza, M., Prediction of unsteady flow around square and rectangular section cylinders using a discrete vortex method, Journal of Wind Engineering and Industrial Aerodynamics, 82 , 247 – 269, 1999
  • [10] Taylor, I. and Vezza, M., Calculation of the flow field around a square section cylinder undergoing forced transverse oscillations using a discrete vortex method, Journal of Wind Engineering and Industrial Aerodynamics, 82, 271 – 291, 1999
  • [11] Viswanath, P.R., Drag reduction of after bodies by controlled separated flows, AIAA J., 39, 73-78, 2001.
  • [12] Watanabe, K., Characteristics of axial flow around step cylinder (parallel flow), Trans. Japan Society of Mechanical Engineers, B, 62, 2130-2136, 1996 (in Japanese).
  • [13] I. Taylor, M. Vezza, Calculation of the flow field around a square section cylinder undergoing forced transverse oscillations using a discrete vortex method. Journal of Wind Engineering and Industrial Aerodynamics, Vol. 82, P271 – 291, 1999
Yıl 2010, Cilt: 2 Sayı: 4, 83 - 92, 01.12.2010

Öz

Kaynakça

  • [1] Kentfield, J.A.C, Short, Multi-step After Fairings, J. Aircraft, 12, 351-352, 1984.
  • [2] Koenig, K and Rosko, A., An experimental study of geometrical effects on the drag and flow field of two bluff bodies separated by a gap, J. Fluid Mech., 156, 167-204,1985.
  • [3] Morel, T., Theoretical lower limits of forebody drag, Aero. J., 83, 23-27,1979.
  • [4] Ota, T., Asano, T. and Okawa, J., Reattachment length and transition of separated flow over blunt flat plates, bulletin of the Japan Society for Mechanical Engineers, 24, 941-947, 1981.
  • [5] Prandtl, L. and Tietjens, O.G., Applied Hydro-and Aeromechanics (translated by J.P. Hartog), SS77-81, Dover; 1934.
  • [6] Ringleb, F.O., Separation Control by trapped vortices, Boundary layer, and Flow control, edited G.V. Lachmann, Pergamon, Oxford, 265-294, 1961.
  • [7] Roshko, A., On the Wake and Drag of Bluff Bodies, J. Aero. Sci.. 22, 2-** , 1955.
  • [8] Saunders, W.D., Apparatus for reducing linier and lateral wind resistance in a tractor-trailer combination vehicle, U.S. Patent No. 3241876, 1966.
  • [9] Taylor, I. and Vezza, M., Prediction of unsteady flow around square and rectangular section cylinders using a discrete vortex method, Journal of Wind Engineering and Industrial Aerodynamics, 82 , 247 – 269, 1999
  • [10] Taylor, I. and Vezza, M., Calculation of the flow field around a square section cylinder undergoing forced transverse oscillations using a discrete vortex method, Journal of Wind Engineering and Industrial Aerodynamics, 82, 271 – 291, 1999
  • [11] Viswanath, P.R., Drag reduction of after bodies by controlled separated flows, AIAA J., 39, 73-78, 2001.
  • [12] Watanabe, K., Characteristics of axial flow around step cylinder (parallel flow), Trans. Japan Society of Mechanical Engineers, B, 62, 2130-2136, 1996 (in Japanese).
  • [13] I. Taylor, M. Vezza, Calculation of the flow field around a square section cylinder undergoing forced transverse oscillations using a discrete vortex method. Journal of Wind Engineering and Industrial Aerodynamics, Vol. 82, P271 – 291, 1999
Toplam 13 adet kaynakça vardır.

Ayrıntılar

Diğer ID JA65KH88RT
Bölüm Makaleler
Yazarlar

K. M. Rahman Bu kişi benim

M. Mashud Bu kişi benim

Yayımlanma Tarihi 1 Aralık 2010
Yayımlandığı Sayı Yıl 2010 Cilt: 2 Sayı: 4

Kaynak Göster

APA Rahman, K. M., & Mashud, M. (2010). Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle. International Journal of Engineering and Applied Sciences, 2(4), 83-92.
AMA Rahman KM, Mashud M. Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle. IJEAS. Aralık 2010;2(4):83-92.
Chicago Rahman, K. M., ve M. Mashud. “Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle”. International Journal of Engineering and Applied Sciences 2, sy. 4 (Aralık 2010): 83-92.
EndNote Rahman KM, Mashud M (01 Aralık 2010) Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle. International Journal of Engineering and Applied Sciences 2 4 83–92.
IEEE K. M. Rahman ve M. Mashud, “Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle”, IJEAS, c. 2, sy. 4, ss. 83–92, 2010.
ISNAD Rahman, K. M. - Mashud, M. “Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle”. International Journal of Engineering and Applied Sciences 2/4 (Aralık 2010), 83-92.
JAMA Rahman KM, Mashud M. Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle. IJEAS. 2010;2:83–92.
MLA Rahman, K. M. ve M. Mashud. “Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle”. International Journal of Engineering and Applied Sciences, c. 2, sy. 4, 2010, ss. 83-92.
Vancouver Rahman KM, Mashud M. Numerical Study of Flow Stabilization Mechanism of Stepped-Nosed Obstacle. IJEAS. 2010;2(4):83-92.

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