Reduction of Turbulent Skin Friction by Microbubbles

Abstract

Measurements of the effect of microbubbles on a zero pressure gradient turbulent boundary layer generated on the test section wall of a water tunnel are described. Microbubbles were created by injecting air through a 0.5 micron sintered stainless steel plate immediately upstream of a floating element drag balance. At the downstream edge of the balance the length Reynolds number was as high as ten million. Integrated skin friction reduction of greater than 80% was observed. The drag balance results were confirmed by measurements with surface hot film probes. For the case in which buoyancy tended to keep the bubbles in the boundary layer, the skin friction data was shown to collapse when plotted against the ratio of air to water volume flow rate. The effects of buoyancy on skin friction reduction were also documented.

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Document Details

Document Type
Technical Report
Publication Date
Mar 09, 1983
Accession Number
ADA243008

Entities

People

  • C. L. Merkle
  • N. K. Madavan
  • S. Deutsch

Organizations

  • Pennsylvania State University

Tags

Communities of Interest

  • Weapons Technologies

DTIC Thesaurus Topics

  • Air Flow
  • Boundary Layer
  • Buoyancy
  • Drag Reduction
  • Engineering
  • Free Stream
  • Hydrodynamics
  • Measurement
  • Mechanical Engineering
  • Military Research
  • Navy
  • Pressure Gradients
  • Skin Friction
  • Thickness
  • Turbulent Boundary Layer
  • Universities
  • Water Tunnels

Fields of Study

  • Physics

Readers

  • Fluid Dynamics.
  • Tribology (the study of the boundary interaction between sliding surfaces, lubrication, wear and friction).
  • Underwater engineering and Marine Technology.