Boundary layer ingesting (BLI) propulsion systems offer potential fuel burn reduction for civil aviation and synergize with new advanced airframe concepts. However, the distorted inlet flow for BLI systems can cause performance and stability margin loss. System level analyses generally size a single engine at a fixed design point which ignores the distributed nature of many BLI architectures. Furthermore, operability and performance during o design are generally not considered during the sizing process. In this thesis, a methodology is developed for multi-design point sizing of BLI propulsion systems for specific vehicle geometry including an operability constraint. The methodology is applied to a 300 passenger hybrid-wing body vehicle with embedded turbofan engines. The methodology required investigations into three main areas of research. The first was the modeling of BLI impacts over a range of flight conditions. A BLI analysis tool was developed which models the vehicle boundary layer, pre-entry region, inlet, and fan losses throughout the entire flight envelope. An experiment investigating the impact of the modeling approach is conducted, and results show that proper mapping of the fan, inlet, and BLI propulsive benefit is crucially important for making proper design decisions. The impact of BLI on the system was found to vary significantly during o ff design and especially with changes in vehicle angle of attack. The operability constraint is investigated using a parallel compressor model and was found to place a minimum limit on the propulsor height. The second area of investigation was the creation of a multi-propulsor sizing methodology which accounts for diff erences between propulsors during flight that is induced by their interaction with the vehicle. A modified multi-design point approach was used which employs a set of design and power management rules to relate the operation of the propulsors. A performance comparison of this methodology with the standard single propulsor approach showed a signicant difference. The final area of investigation was the determination of critical o ff-design conditions for the sizing procedure. A screening process is developed which tests all off -design conditions for a subset of the design space to find conditions which are stall margin or thrust deficient. The experiment showed that it is necessary to consider the high angle of attack take-off condition during sizing for the HWB vehicle and that a variable area nozzle is required to meet the operability constraint. A follow on experiment showed that the inclusion of this point reduced the achievable fuel burn benefit for more aggressive BLI designs.Boundary layer ingesting (BLI) propulsion systems offer potential fuel burn reduction for civil aviation and synergize with new advanced airframe concepts. However, the distorted inlet flow for BLI systems can cause performance and stability margin loss. System level analyses generally size a single engine at a fixed design point which ignores the distributed nature of many BLI architectures. Furthermore, operability and performance during o design are generally not considered during the sizing process. In this thesis, a methodology is developed for multi-design point sizing of BLI propulsion systems for specific vehicle geometry including an operability constraint. The methodology is applied to a 300 passenger hybrid-wing body vehicle with embedded turbofan engines. The methodology required investigations into three main areas of research. The first was the modeling of BLI impacts over a range of flight conditions. A BLI analysis tool was developed which models the vehicle boundary layer, pre-entry region, inlet, and fan losses throughout the entire flight envelope. An experiment investigating the impact of the modeling approach is conducted, and results show that proper mapping of the fan, inlet, and BLI propulsive benefit is crucially important for making proper design decisions. The impact of BLI on the system was found to vary significantly during o ff design and especially with changes in vehicle angle of attack. The operability constraint is investigated using a parallel compressor model and was found to place a minimum limit on the propulsor height. The second area of investigation was the creation of a multi-propulsor sizing methodology which accounts for diff erences between propulsors during flight that is induced by their interaction with the vehicle. A modified multi-design point approach was used which employs a set of design and power management rules to relate the operation of the propulsors. A performance comparison of this methodology with the standard single propulsor approach showed a signicant difference. The final area of investigation was the determination of critical o ff-design conditions for the sizing procedure. A screening process is developed which tests all off -design conditions for a subset of the design space to find conditions which are stall margin or thrust deficient. The experiment showed that it is necessary to consider the high angle of attack take-off condition during sizing for the HWB vehicle and that a variable area nozzle is required to meet the operability constraint. A follow on experiment showed that the inclusion of this point reduced the achievable fuel burn benefit for more aggressive BLI designs.

This research investigated the role of the intestinal microbiota in shaping host food intake and body weight through immunomodulation, the impact of refined and unrefined diets, and though fermentable fibre induced gastrointestinal hormone secretion. Gut-derived lipopolysaccharide activating TLR4 has been proposed to contribute to obesity. To investigate this, TLR4-/- or CD14-/- mice and C57BL/6J controls were fed a high-fat or low-fat diet. Neither TLR4-/- or CD14-/- were protected against high-fat diet-induced obesity. High-fat diet increased hypothalamic expression of SerpinA3N and SOCS3 regardless of genotype; however, inflammatory gene expression was not increased. To investigate the use of chow control diets in obesity-associated microbiota changes, C57BL/6J mice were fed a chow diet, refined high-fat, or low-fat diet. Both high-fat and low-fat refined diets resulted in similar dramatic alterations in the composition of the intestinal microbiota at the phylum, family, and species level compared to chow, while only high-fat diet feeding resulted in obesity and glucose intolerance. The roles of colonic GLP-1 and PYY in mediating fermentable fibre in reducing food intake and body fat were investigated using GLP-1R-/- and PYY-/- mice fed a high-fat diet supplemented with inulin or cellulose. Inulin supplementation reduced body fat and food intake in C57BL/6J control mice while GLP-1R-/- and PYY-/- mice showed an attenuated response to dietary inulin. In summary, this research questions the role of TLR4 and LPS in diet-induced obesity. These results demonstrate the importance of the control diet used in studies of obesity in mice and indicate that many of the obesity-associated changes in the gut microbiota are due to comparing refined high-fat diets with chow diets. These results also provide evidence for an essential role for both GLP-1 and PYY in mediating the food intake and bodyweight-reducing effects of fermentable fibre.

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A monitoring effort that spanned across one and a half years was conducted to examine three types of produce-associated microbiota. Produce type was determined to be the predominant factor affecting the microbial communities. Other significant factors that resulted in differences in the microbial populations were the origin and sampling date. Specifically, produce-associated microbiota among lettuce and tomatoes clustered based on the sampling period. Through molecular and cultivation-based approaches, sporadic presence of extended spectrum beta-lactamase (ESBL)-positive Klebsiella pneumoniae and Acinetobacter baumannii was detected on lettuce and cucumbers during certain periods of sampling. Quantitative microbial risk assessment denoted varying levels of ingestion risks associated with different types of produce. In particular, the risks arising from ESBL-positive K. pneumoniae in the lettuce were higher than the acceptable annual risk of 10-4. Commonly used approaches to clean and wash the produce were insufficient in removing majority of the produce-associated microbiota. More invasive cleaning approaches or thorough cooking of the produce would be required to mitigate the associated risks. Most of the current reports of ESBL-positive bacterial isolates were identified in nosocomial environment. However, the carriage of such drug-resistant bacteria in food that is consumed daily

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Gas turbine engines for propulsion operate under harsh conditions including gas temperatures that exceed the melting point of the metal, high mechanical stresses, and particulate ingestion such as sand. To maintain a low and uniform metal temperature to extend the life of a turbine component, a complex scheme of internal convective cooling and external film-cooling is required. Gas turbine engines operated in sandy or dusty environments can ingest a large quantity of sand into the mainstream and, more importantly, into the cooling system. Sand ingested into the coolant system has the potential to reduce or block off the flow intended to cool the turbine blades or vanes. If the source of coolant air to a critical region of a turbine blade were partially blocked, it would result in a substantial reduction in component life. This study includes establishing a methodology for testing sand ingestion characteristics on a simulated turbine component with film-cooling holes at room temperature and engine temperatures. The study evaluates a simple array of laser drilled film-cooling holes, similar to a showerhead on the leading edge of an airfoil. The blocking characteristics of this design indicate that increasing the airflow or decreasing the sand amount results in a decreased blockage. It was also determined that as the metal temperature increases, the blockage from a given amount of sand increases. The methodology used in the primary portion of this thesis was modified to test sand ingestion characteristics on actual turbine blades with film-cooling holes at room temperature and engine temperatures. The study evaluated the blockage performance of several different turbine blades including the F-100-229-full, F-100-229-TE, and the F-119 with a new trailing edge cooling methodology know as a microcircuit. It was shown that increasing the airflow or pressure ratio, or decreasing the sand amount would result in decreased blockage. It was also shown that over a certain metal and coolant temperature, the blockage is significantly worsened. However, it was also shown on the F-119 turbine blade that below a given metal temperature, there is no impact of metal or coolant temperature on sand blockage. / Master of Science

Modern gas turbine engines operate in environments where particle ingestion, especially sand ingestion, can affect the cooling of various turbine parts. The most critical areas are in the combustor and the first stage components of the turbine. Gas temperatures in these areas are the highest compared to other areas and exceed the melting points of the constituent metals. To extend the life of hot section components, internal convective cooling and external film-cooling are required. This study examined the effects of sand ingestion on various cooling geometries. The first part investigated impingement and film-cooling implemented in a double-walled cooling geometry for the purpose of reducing sand size and thereby reducing blockage due to sand ingestion. The second part analyzed the cooling performance of actual turbine blade outer air seals injected with sand. Results from these studies showed areas of impingement that promote particle fragmentation are advantageous in reducing particle size and reducing blockage due to particle ingestion. Blockage was significantly increased based on the percentage of large particles present in the sand samples. Increasing the pressure ratio and decreasing the sand amount were also shown to reduce blockage. / Master of Science