Accession Number : AD0438450


Title :   SITTING TIME AND STRAIN EFFECTS IN A .00005 INCH DIAMETER COLD WIRE FOR LOW DENSITY SHOCK TUBE USE.


Descriptive Note : Final rept. Nov 63-Apr 64,


Corporate Author : FRANK J SEILER RESEARCH LAB UNITED STATES AIR FORCE ACADEMY COLO


Personal Author(s) : Stebbins,Charles F


Report Date : 07 Apr 1964


Pagination or Media Count : 23


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)


Descriptors :   *WIRE , *HEAT TRANSFER , STRAIN(MECHANICS) , MEASUREMENT , SHOCK WAVES , SHOCK TUBES , VIBRATION , HYPERSONIC FLOW , SUBSONIC FLOW , SHOCK RESISTANCE , DRAG , SIMULATION , INSTRUMENTATION , TENSILE PROPERTIES , WIND TUNNELS , PHYSICAL PROPERTIES , MOLECULAR PROPERTIES


Distribution Statement : APPROVED FOR PUBLIC RELEASE