DRAG REDUCTION IN A RECTANGULAR DUCT USING RIBLETS

An experimental investigation has been made into the effects of riblets on the drag in a rectangular duct of aspect ratio 10. It has been found that a maximum drag reduction of approximately 10% occurs in fully developed turbulent flow. This figure is larger than the 6-8% drag reduction usually found for external flow. The maximum drag reduction occurred when the height of the riblets was between 7 and 13 wall units. Analysis of the developing region of the flow has shown a maximum drag reduction of approximately 8% at a wall unit value of 13, consistent with results in external flows. The effects of riblets on transition has also been investigated. It was found that riblets delayed transition by 2-4% in critical Re as measure by peak flatness, and caused some extension in the length of the transition process, so that the completion of transition was delayed by between 4-8%, with the stronger effect at the lower Reynolds numbers.

• Supplemental Notes:
  • Aeronautical J, v 99 n 985, May 1995, p 187 [7 p, 12 ref, 16 fig]
• Authors:
  • Moore, A R
  • Lowson, M V
• Publication Date: 1995

Language

• English

Subject/Index Terms

• TRT Terms: Drag; Ducts; Flow
• Old TRIS Terms: Drag reduction
• Subject Areas: Bridges and other structures; Marine Transportation;

Filing Info

• Accession Number: 00717745
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Mar 4 1996 12:00AM