OBSERVATIONS ON THE INFLUENCE OF AMBIENT PRESSURE ON BOUNDARY-LAYER TRANSITION

Abstract

For at least 15 yrs it has been known that the Reynolds number characterizing transition form laminar to turbulent boundary-layer flow (based on local properties and wetted length to transition) may be influenced by the local unit Reynolds number or some still unidentified, related quantity under both subsonic and supersonic conditions. Because examples of this were available almost exclusively from wind tunnel work, and because of the possibility that free-stream disturbances were responsible, there has been uncertainty as to whether the so-called unit Reynolds number effect exists in atmospheric free flight. The study described in the report was conducted in a free-flight range, thereby circumventing 'wind tunnel effects,' and it has resulted in a demonstration of the variation of transition Reynolds number with range pressure (or unit Reynolds number) under conditions of fixed Mach number and average wall temperature ratio. Some preliminary measurements of sound pressures in the range air are reported for comparison with published results for wind tunnels.

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1968
Accession Number
AD0666911

Entities

People

  • J. L. Potter

Organizations

  • Arnold Engineering Development Complex

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Air Force
  • Boundaries
  • Boundary Layer
  • Boundary Layer Transition
  • Flight
  • Flow
  • Fluid Mechanics
  • Free Flight
  • Free Stream
  • Layers
  • Mach Number
  • Measurement
  • Reynolds Number
  • Sound Pressure
  • Surface Properties
  • Turbulent Boundary Layer
  • Wind Tunnels

Fields of Study

  • Physics

Readers

  • Fluid Dynamics.
  • Fluid Mechanics and Fluid Dynamics.
  • Systems Analysis and Design

Technology Areas

  • Hypersonics
  • Hypersonics - Hypersonic Boundary Layers
  • Hypersonics - Hypersonic Flow