SITTING TIME AND STRAIN EFFECTS IN A .00005 INCH DIAMETER COLD WIRE FOR LOW DENSITY SHOCK TUBE USE.
Abstract
The very fine, cold wire (diameter < .00005 in.), a comparatively new instrument for use in fasttransient, free-molecule-flow problems, has been used to measure heat transfer rates within a plane shock wave up to shock Mach numbers of 7.5. However, discrepancies exist between theoretical predictions and experimental results. In an effort to resolve these discrepancies, several characteristics of the very fine, cold wire are investigated. These include strain-induced-resistance changes and molecular sitting time. Sitting time, the finite time increment involved in the transfer of thermal energy between a surface and an impinging molecule, is shown to be three orders of magnitude smaller than shock-passage time, thus causing no appreciable error in the results. The elimination of concern with these two effects under certain conditions brings the cold-wire closer to the status of an acceptable instrument for fast-transient, free-molecule-flow applications. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 07, 1964
- Accession Number
- AD0438450
Entities
People
- Charles F. Stebbins
Organizations
- United States Air Force Academy