Type of Document Dissertation Author Rolling, August Jameson URN etd-06212007-161239 Title Design of Gages for Direct Skin Friction Measurements in Complex Turbulent Flows with Shock Impingement Compensation Degree PhD Department Aerospace and Ocean Engineering Advisory Committee
Advisor Name Title Schetz, Joseph A. Committee Chair Boyer, Keith M. Committee Member Hallauer, William L. Jr. Committee Member Kapania, Rakesh K. Committee Member MacLean, Matthew Committee Member Keywords
- wall shear
- shock impingement
- complex turbulent flow
- skin friction
Date of Defense 2007-06-07 Availability unrestricted AbstractThis research produced a new class of skin friction gages that measures wall shear even in shock environments. One test specimen separately measured wall shear and variable-pressure induced moment. Through the investigation of available computational modeling methods, techniques for accurately predicting gage physical responses were developed. The culmination of these model combinations was a design optimization procedure. This procedure was applied to three disparate test conditions: 1) short-duration, high-enthalpy testing, 2) blow-down testing, and 3) flight testing. The resulting optimized gage designs were virtually tested against each set of nominal load conditions. The finalized designs each successfully met their respective test condition constraints while maximizing strain output due to wall shear.
These gages limit sources of apparent strain: inertia, temperature gradient, and uniform pressure. A unique use of bellows provided a protective shroud for surface strain gages. Oil fill provided thermal and dynamic damping while eliminating uniform pressure as a source of output voltage. Two Wheatstone bridge configurations were developed to minimize temperature effects first from temperature gradient and then from spatially varying heat flux induced gradient. An inertia limiting technique was developed that parametrically investigated mass and center of gravity impact on strain output.
Multiple disciplinary computational simulations of thermal, dynamic, shear, moment, inertia, and instrumentation interaction were developed. Examinations of instrumentation error, settling time, filtering, multiple input dynamic response, and strain gage placement to avoid thermal gradient were conducted. Detailed mechanical drawings for several gages were produced for fabrication and future testing.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access RollingVT2007July3.pdf 3.03 Mb 00:14:02 00:07:13 00:06:19 00:03:09 00:00:16
If you have questions or technical problems, please Contact DLA.