Breast cancer is the most common cancer among women. Statistics released by the American Cancer Society (1999) show that every 1 in 8 women in the United States is likely to get breast cancer during her lifetime. Thermography, also known as thermal or infrared imaging, is a procedure to determine if an abnormality is present in the breast tissue temperature distribution, which may indicate the presence of an embedded tumor. In the year 1982, the United States Food and Drug Administration (FDA) approved thermography as an adjunct method of detecting breast cancer, which could be combined with other established techniques like mammography. Although thermography is currently used to indicate the presence of an abnormality, there are no standard protocols to interpret the abnormal thermal images and determine the size and location of an embedded tumor. This research explores the relationship between the physical characteristics of an embedded tumor and the resulting temperature distributions on the skin surface. Experiments were conducted using a resistance heater that was embedded in agar in order to simulate the heat produced by a tumor in the biological tissue. The resulting temperature distribution on the surface was imaged using an infrared camera. In order to estimate the location and heat generation rate of the source from these temperature distributions, a genetic algorithm was used as the estimation method. The genetic algorithm utilizes a finite difference scheme for the direct solution of Pennes bioheat equation. It was determined that a genetic algorithm based approach is well suited for the estimation problem since both the depth and the heat generation rate of the heat source were accurately predicted. Thermography can prove to be a valuable tool in locating tumors if combined with such an algorithm. / Master of Science

In gas turbine development, the direction has been toward higher turbine inlet temperatures to increase the work output and thermal efficiency. This extreme environment can significantly impact component life. One means of preventing component burnout in the turbine is to effectively use film-cooling whereby coolant is extracted from the compressor and injected through component surfaces. One such surface is the endwall of the first stage nozzle guide vane. This thesis details the design, prediction, and testing of two endwall film-cooling hole patterns provided by leading gas turbine engine companies. In addition a flush, two-dimensional slot was included to simulate leakage flow from the combustor-turbine interface. The slot coolant was found to exit in a non-uniform manner leaving a large, uncooled ring around the vane. Film-cooling holes were effective at distributing coolant throughout much of the passage, but at low blowing rates were unable to provide any benefit to the critical vane-endwall junction both at the leading edge and along the pressure side. At high blowing ratios, the increased momentum of the jets induced separation at the leading edge and in the upstream portion of the passage along the pressure side, while the jets near the passage exit remained attached and penetrated completely to the vane surface. Computational fluid dynamics (CFD) was successful at predicting coolant trajectory, but tended to under-predict thermal spreading and jet separation. Superposition was shown to be inaccurate, over-predicting effectiveness levels and thus component life, because the flow field was altered by the coolant injection. / Master of Science

A thermal analysis of a conventional vaporization source by finite difference methods, including experimental validation, is presented. Such a system is common to industries whose chief concern is the precipitation of inorganic coatings. Both the physical and the model systems are comprised of a number of layers, or strata, arranged in a rectangular configuration. The model strata represent the component and deposition materials of the physical vaporization source. The symmetry and simplistic geometry of the operational source permit the use of a two-dimensional model, thereby neglecting gradients in the third dimension. The production unit, as well as the numerical model, experience various modes of heat transfer, including radiation, convection, conduction, internal generation, and phase change. Moreover, the system inputs are time-dependent. The numerical model is subsequently compared to and validated against both simplistic case studies and the physical production system. Data collected from the operational deposition source is examined and analyzed in comparison to corresponding information generated by the numerical model. Sufficient agreement between the data sets encourages the utilization of the numerical model as a practical indicator of the subject system's behavior. Finally, recommendations for modifications to the physical vaporization source, yielding practical improvements in temperature uniformity, are evaluated based on the predictions of the validated numerical model. The goal is the attainment of an ideally uniform temperature distribution that would correspond to highly desirable performance of the process vaporization system. / Master of Science

The accurate measurement of total temperature in engine diagnostics is a challenging task which is subject to several sources of error. Conduction error is predominant among these sources since total temperature sensors are embedded into a cooled strut for measurement. This study seeks to understand the effect of conduction error on total temperature probe performance from an analytical and experimental standpoint and to provide an effective calibration procedure. The review of historical low-order models, as well as results from a developed thermal resistance model, indicates that conduction error is driven by dimensionless parameters, including the Biot, Nusselt, and Reynolds Numbers, as well as a non-dimensional temperature characterizing the flow/strut temperature difference. A conduction error calibration procedure for total temperature probes is experimentally tested in this study. Data were acquired for nominal flow total temperatures ranging from 550 °F to 850 °F with the probe Reynolds number varying from 2,000 to 12,000 for varying conduction conditions with axial temperature gradients up to 1150 °F per inch. A physics-based statistical model successfully expressed total temperature probe performance as a function of dimensionless conduction driver and probe Reynolds number. This statistical model serves as a “calibration surface” for a particular total temperature probe. Due to the scaling of the problem, this calibration is experimentally obtained in moderate temperature regimes, then implemented in higher temperature regimes. The calibration yields an overall uncertainty in total temperature measurement to be ±4% of the total temperature for flow conditions typical in engine diagnostics, with extreme uncertainties in input conditions. Conduction error is successfully shown to be independent of any temperature regime and driven by dimensionless parameters. / Master of Science

Engine designers continually push the combustor exit temperature higher to produce more power from gas turbine engines. These high turbine inlet temperatures, coupled with high turbulence levels and flow field non-uniformities, make turbine vane and endwall cooling a very critical issue in engine design. To appropriately cool these surfaces, knowledge of the passage flow field and endwall temperature distribution at representative engine conditions is necessary. A combustor test section was used to simulate realistic turbine inlet profiles of turbulence, normalized temperature, normalized total pressure, and normalized streamwise velocity to study the flow field in a turbine vane passage and the adiabatic temperature distribution on the endwall. The combustor liner film-cooling and exit slot flows were varied independently to determine their relative effect on endwall cooling in the downstream turbine vane. Flow field measurements revealed the presence of a previously unmeasured third vortex in the vane passage. The tertiary vortex was located above the passage vortex and had rotation opposite to the passage vortex. Increasing the amount of slot flow reduced the size and strength of the nearwall vortices, while increasing the size and strength of the tertiary vortex. Adiabatic endwall temperature measurements revealed higher temperatures surrounding the base of the vane. The endwall measurements also showed that the exit slot flow was effective at cooling only a region of the endwall near the vane leading edge on the suction side. Increasing slot flow was found to have a larger thermal benefit to the endwall relative to increasing combustor liner film-cooling. / Master of Science

Yes / The influence of the dyeing industry in Pompeii on the local economy has been under discussion since the publication by Moeller in 1976. Since no absolute answer has emerged, the question was re-examined using two additional methods, experimental archaeology and the principles of thermodynamics. A full-scale replica of a dyeing apparatus from Pompeii was constructed and used to simulate repeated dye runs, and so determine operating parameters such as the times involved to heat and cool a vat and the consumables needed. This first replica also allowed a better understanding of how the apparatus was actually used. Thermodynamic principles, which were applied to understand the successes and failures within the experimental work, suggested that the vat operated in a predictable way and enabled the operational mechanics of the vat to be established. It is now possible to use both the experimental results and the thermodynamic modelling to determine not just the consumables used, but also the working environment needed for the vat to operate, allowing an understanding of the limitations to dyeing and to workers. Issues of practicality such as storage of consumables and disposal of exhaust gases may now be thoroughly examined. 2 Eventually it will be possible to determine the operating parameters of each of the dye vats, the quantities of consumables involved and the amount that could be produced. This should help answer the question as to the significance of the dye industry in Pompeii to the local economy.

The relationship between the plenum to freestream total pressure ratio on film cooling performance is experimentally investigated. Measurements of both the heat transfer coefficient and the adiabatic effectiveness were made on the suction side of the center blade in a linear transonic cascade. Entrance and exit Mach numbers were 0.3 and 1.2 respectively. Reynolds number based on chord and exit conditions is 3 x 10⁶. The blade contour is representative of a typical General Electric first stage, high turning, turbine blade. Tunnel freestream conditions were 10 psig total pressure and approximately 80 °C. A chilled air coolant film was supplied to a generic General Electric leading edge showerhead coolant scheme. Pressure ratios were varied from run to run over the ranges of 1.02 to 1.20. The density ratio was near a value of 2. A method to determine both the heat transfer coefficient and film cooling effectiveness from experimental data is outlined. Results show that the heat transfer coefficient is independent of the pressure ratio over these ranges of blowing parameters. Also, there is shown to be a weak reduction of film cooling effectiveness with higher pressure ratios. Results are shown for effectiveness and heat transfer coefficient profiles along the blade. / Master of Science

Microwave tempering experiments were conducted on frozen blocks of shrimp (FSB) and the results were used to help determine if microwave tempering of FSB is an improved thawing method over the current, traditional method, water immersion. Results of the microwave tempering experiments were also used to help determine which microwave tempering method amongst those explored by this study is most effective. Complete thawing of a FSB in a microwave oven was found to be impractical; however, using a combination of microwave tempering followed by water immersion can successfully thaw a FSB. After a microwave tempering experiment was conducted, the final stages of thawing were completed by using the traditional water immersion method. The amount of time to complete the thawing was recorded and is referred to as the additional thawing time. The amount of shrimp cooked during microwave tempering was also recorded and calculated as a percent. The additional thawing time and the percentage of shrimp cooked were used as criteria to compare microwave tempering experiments and also to compare microwave tempering experiments with the current method. The first set of microwave tempering experiments explored the advantages of freezing a microwave susceptive material within the FSB before microwave tempering. FSBs with susceptors and FSBs without susceptors were tempered in a microwave oven. The FSBs were tempered in a 2450 MHz microwave oven at 255 W for 35 minutes and at 406 W for 22 minutes. The results showed that the addition of susceptors does improve the microwave tempering process. The percentage of cooked shrimp and the additional thawing time was less for FSBs with susceptors than for FSBs without susceptors. The susceptors seem to help distribute the microwave energy more evenly, which reduces runaway heating and in turn reduces the amount of shrimp cooked. When compared to the current method, microwave tempering with susceptors reduced the total thawing time by 45% while microwave tempering without susceptors reduced the total thawing time by 43%. Both microwave tempering methods, with and without susceptors, are an improvement over the current method. The addition of susceptors does improve the microwave tempering process; however, the improvements are not significant enough to justify its recommendation. The second set of microwave tempering experiments explored the advantages of pulse microwave tempering. During pulsed microwave tempering the microwave oven was set to a high power level and was turned ON for a period of time and then OFF for a period of time. The ON/OFF pattern was repeated throughout the microwave tempering process. Several pulsed tempering experiments were conducted at a microwave power level of 848 W and at a microwave power level of 993 W. The results showed that there is no significant advantage to using pulsed microwave energy during tempering as opposed to continuous, fixed microwave energy. The results showed that fixed microwave tempering is more effective than pulsed microwave tempering. The percentage of cooked shrimp was lower for fixed experiments than for pulsed experiments and the additional thawing time was slightly less for fixed experiments than for pulsed experiments. A mathematical model was developed to help predict he temperature profiles of a FSB during microwave tempering. Experimental temperature data were collected at four locations within the FSB during microwave tempering by using four Luxtron Fluoroptic temperature probes and a Luxtron Fluoroptic thermometer. Overall, the temperatures predicted by the model were within 2 oC of the experimental temperatures. After the first 500 seconds or so of microwave tempering, the temperatures predicted by the model were consistently less than the experimental temperatures. From this study it was determined that the most effective microwave tempering method, amongst those conducted in this study, of a 2.2 kg (5 lb) frozen block of shrimp was accomplished by setting the power output to 255 W and the microwave cooking (tempering) time to 35 minutes. As previously mentioned, the addition of susceptors does improve the process but the improvements are not significant enough to justify its recommendation. Pulse tempering is not an improved method over fixed tempering. / Master of Science

This study documents the integration and testing of a new variety of unsteady surface temperature gages designed to operate in high speed flow. Heat flux through the surface of the test article was determined from the unsteady temperature by applying a 3D reconstruction algorithm based on a Green's function approach. The surface temperature gages used in this work were 1.59 mm inserts designed to maximize material matching with the test article, in this case 316 stainless steel. A series of benchtop experiments were first performed to understand the individual properties of the gage and determine measurement uncertainty. Prior to testing, all temperature gages are calibrated using an environmental chamber. Gages were installed into slugs of several materials and subjected to a heated jet with a total temperature of 620 K to examine the effects of material mismatch. A shock tube with a notional operating Mach of 2.6 was used to determine the thermal response of the gages as a function of time. In both tests, reference Medtherm Schmidt-Boelter gages ensure consistent heat fluxes are applied across all runs. The time response of the entire electrical system was determined by subjecting the gage to a nanosecond scale laser pulse. Two experimental campaigns were conducted in Virginia Tech's Hypersonic Wind Tunnel. First, gages were integrated into a flat plate test article and subjected to a notionally 2D Mach 3 flow. Tunnel total pressures and temperatures ranged from 793-876 kPa and 493-594 K, respectively. A reference 3.18 mm Medtherm Schmidt-Boelter gage was also installed for comparison. All temperature data are reconstructed using the algorithm to determine heat flux. The second test campaign utilized a flat-faced cylindrical test article in a notionally axisymmetric Mach 6 flow environment. Flow total pressures and temperatures ranged from 8375-8928 kPa and 485.5-622 K. respectively. The Fay-Riddell analytical method was applied to the resulting temperature traces in order to infer the heat flux at the stagnation point for comparison with the reconstructed heat flux. This experiment was complimented with steady, 3D CFD in order to understand the temperature variation across the test article. Both campaigns demonstrate good agreement between the heat flux reconstructed from surface temperatures measured using the new gage, reference measurements, and simulations/analytical methods. The importance of material matching is highlighted during this study. The performance of this gage is shown to exceed the current state-of-the-art, opening the possibility for future analysis of phenomenon present in high-speed flow. / Doctor of Philosophy / At very fast speeds, it is important to understand how the temperatures of surfaces change with time. Traditional devices which can measure surface temperatures have a number of weaknesses, and to address these a new type of surface temperature device has been designed. By using computational methods, one can determine how much energy is being transferred through the surface by measuring how the surface temperature changes over time. A series of laboratory experiments were conducted to understand how this new instrument compares to the current state-of-the-art. Two experimental campaigns were then conducted to test the temperature gages. The first experiment used a simple flat plate geometry in a flow 3 times the speed of sound to serve as a benchmark test case, as the flow over a flat plate is well understood. The second test utilized a flat-faced cylindrical test article in a flow 6 times the speed of sound. The results of this test was compared to exact solutions and flow simulations. The result of this study is a well quantified tool to study how energy flows through a body subjected to very high speed flow, which will enable further study of the complicated thermal environments experienced at high speeds.

Considerable reductions in gas turbine weight and fuel consumption can be achieved by operating at a higher turbine entry temperature. The move to lean combustors with flatter outlet temperature profiles will increase temperatures on the turbine endwalls. This work will study methods to improve endwall film cooling, to allow these advances. Turbine secondary flows are caused by a deficit in near-wall momentum. These flow features redistribute near-wall flows and make it difficult to film-cool endwalls. In this work, endwall film cooling was studied by CFD and validated by experimental measurements in a linear cascade. This study will add to the growing body of evidence that injection of high momentum coolant into the upstream boundary layer can suppress secondary flows by increasing near-wall momentum. The reduction of secondary flows allows for effective cooling of the endwall. It is also noted that excess near-wall momentum is undesirable. This leads to upwash on the vane, driving coolant away from the endwall. A passive-scalar tracking method has been devised to isolate the contribution of individual film cooling holes to cooling effectiveness. This method was used to systematically optimize endwall cooling systems. Designs are presented which use half the coolant mass flow compared to a baseline design, while maintaining similar cooling effectiveness levels on the critical trailing endwall. By studying the effect of coolant injection on vane inlet total pressure profile, secondary flows were suppressed and upwash on the vane was reduced. The methods and insight obtained from this study were applied to a high pressure nozzle guide vane endwall from a current engine. The optimized cooling system developed offers significant improvement over the baseline.