DRAG MEASUREMENT IN A LOW DENSITY GAS STREAM

Abstract

Two methods of measuring the drag of bodies in a low density gas stream are described. The supersonic stream had a mean free path as great at 4 cm, and the drag forces were small. A drag balance was adapted from an electrical analytical balance to measure forces up to 70 dynes with less than 1- percent error. With this balance, the drag of spheres was measured for the Knudsen number range from 1.0 to 5. The freedrop trajectory method yielded drag coefficients in the range of Knudsen numbers from 2.5 to 30. These tests demonstrated the feasibility of making accurate drag measurements under the free-molecule conditions that can be generated by exhausting a gas into a cryogenically pumped vacuum chamber.

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Document Details

Document Type
Technical Report
Publication Date
May 01, 1970
Accession Number
AD0705576

Entities

People

  • D. Whitfield
  • W. Stephenson

Organizations

  • Arnold Engineering Development Complex

Tags

Communities of Interest

  • Space
  • Weapons Technologies

DTIC Thesaurus Topics

  • Air Force
  • Boundary Layer
  • Chambers
  • Coefficients
  • Dynamic Pressure
  • Flow
  • Fluid Dynamics
  • Gas Flow
  • Knudsen Number
  • Low Density
  • Mach Number
  • Mean Free Path
  • Measurement
  • Molecules
  • Photographs
  • Trajectories
  • Vacuum Chambers

Fields of Study

  • Physics

Readers

  • Fluid Dynamics.

Technology Areas

  • Hypersonics
  • Hypersonics - Hypersonic Flow