Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1990. / Vita. Abstract. Includes bibliographical references (leaves 88-91). Also available via the Internet.

Thesis (M.S. in Engineering Science)--Naval Postgraduate School, December 2003. / Thesis advisor(s): Ashok Gopinath. Includes bibliographical references (p. 83-84). Also available online.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (107-110). Also available via the Internet.

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 153-164.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 66-69). Also available via the Internet.

Thesis (M.S.) University of Missouri-Columbia, 2006. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 29, 2007) Includes bibliographical references.

Two rapid-response thin-film heat flux gage systems have been used to measure time-resolved unsteady heat transfer signals. The Heat Flux Microsensor is a passive gage which measures the temperature difference across a thin thermal resistance. The second sensor, an actively powered gage operated by a constant temperature anemometer, measures heat flux by measuring dissipated power. These gages have frequency performance windows of 50 kHz and 250 Hz, respectively. Each gage was calibrated for both steady and unsteady response. They were then placed at a flow stagnation point. A velocity probe is positioned outside the boundary layer adjacent to the gage. Simultaneous monitoring of these signals allowed the time-resolved documentation of the effects of local freestream turbulence on boundary layer heat transfer. The resulting time traces indicate a direct correlation between the turbulent velocity fluctuations and heat flux variation. The effects of apparent single-frequency turbulent components are isolated on both the velocity and heat flux signals. These signals are analyzed to determine their relative amplitude and phase characteristics. The results are compared to similar relationships characterized in regularly pulsating laminar flow regimes. / Master of Science

A new gage which can measure skin friction and heat flux simultaneously was designed, constructed, and tested. This gage is the combination of a non-nulling type skin friction balance and a heat flux microsensor. By mounting the heat flux microsensor directly on the surface of the floating element of the skin friction balance, it was possible to perform simultaneous measurements of the skin friction and the heat flux. The total thickness of the heat flux microsensor is less than 2 μm, so the presence of this microsensor creates negligible disruption on the thermal and the mechanical characteristics of the air flow. Tests were conducted in the Virginia Tech supersonic wind tunnel. The nominal Mach number was 2.4, and Reynolds number per meter was 4.87 x 10⁷ with total pressure of 5.2 atm and total temperature of 300 °K. Results of the tests showed that this new gage was quite reliable and could be used repeatably in the supersonic flow. This gage also has an active heating system inside of the cantilever beam of the skin friction balance so that the surface temperature of the floating element can be controlled as desired. With these features, the effects of a temperature mismatch between the gage surface and the surrounding wall on the measurements of the skin friction and the heat flux were investigated. An infrared radiometer was used to measure the surface temperature distributions. Without the active heating, the amount of temperature mismatch generated by the gage itself was from 2.5 °K to 4.5 °K. The active heating produced the temperature mismatch of 18.7 °K. The largest temperature mismatch corresponds to the levels typically found in high heat flux cases when it is expressed in dimensionless terms. This temperature mismatch made sizable effects — a 24 % increase in the skin friction measurement and a 580 % increase in the heat flux measurements. These experimental results were compared with the computational results using the Computational Fluid Dynamics code GASP. The input flow conditions were obtained from the boundary layer measurements. The temperature mismatch was input by specifying the density and the pressure at each grid point on the wall. The Baldwin-Lomax algebraic turbulence model was used with the thin layer approximations. The comparison showed that the difference in the skin friction and heat flux was less than 10 % of the measured data when the temperature mismatch was less than 8.5 °K, but the difference was increased as the amount of the temperature mismatch increased. It is presumed that the disagreement between the measurements and the calculations was caused mainly by deficiencies in the turbulence model for this complex, developing viscous flow, because the Baldwin-Lomax model cannot account for the multiple length scale in this flow. / Ph. D.

Instrumentation has been designed to process the signals from two types of skin friction gages and a microfabricated heat flux gage. Design changes for the skin friction gages are presented which will improve the performance of the two transducers. The instrumentation is simple in design and use and has been designed to maximize the performance of the skin friction and heat flux gages. The instrumentation is battery powered to minimize noise levels and to maintain instrumentation portability. A high-quality instrumentation amplifier, a voltage regulator, and a custom-designed circuit board have been combined to produce an instrumentation package which is stable and durable. The instrumentation has been specifically designed to handle low-level signals and can operate over a wide range of frequencies. Problems commonly associated with low-level signal conditioning like electrical noise, nonlinearities, and output drift are addressed. The performance specifications of the instrumentation are presented along with sample gage measurements. / Master of Science

A fast response thin-film heat flux sensor was used to measure the time-resolved surface heat flux and temperature from a turbulent combustion flame impinging on a surface. Using the analytical semi-infinite conduction model, the unsteady surface heat flux was calculated from the transient temperature measurements and the surface temperature was calculated from the unsteady surface heat flux measurements. Methods of comparing time-resolved heat flux and temperature data were presented and discussed. The standard analytical method for converting surface temperature to heat flux was used. Two new analytical methods were developed for converting heat flux to surface temperature. The study is the first demonstration of time-resolved temperature signals generated from time-resolved heat flux measurements. The results graphically illustrate the effects of data processing on electrical noise present in the actual signal. The effect of flame unsteadiness is also shown, especially in the time-resolved heat flux measurements, which gives insight into the behavior of a propane torch. One application is for development of feed-forward control systems in industrial processes with fast transients. / Master of Science