This work develops a methodology for full engine FEA simulation of the fan blade off containment test for a jet engine using LS-Dyna. The fan blade off containment test is a safety requirement involving the intentional release of a fan blade when the engine is running at full power. The released blade must not pierce or fracture the engine cases during the impact or rotating unbalance. The novel feature of the LS-Dyna simulation is the extensive full engine geometry as well as the widespread use of nonlinearities (mainly plasticity and friction) to absorb the large kinetic energies of the engine rotors. The methodology is simple to use, runs quickly and is being recognized by industry as a contender for widespread implementation. Future applications look promising enough that the methodology warrants further development and refinement.

This thesis presents models and algorithms necessary to simulate the five-axis flank milling of jet-engine impellers in a virtual environment. The impellers are used in the compression stage of the engine and are costly, difficult to machine, and time-consuming to manufacture. To improve the productivity of the flank milling operations, a procedure to predict and optimize the cutting process is proposed. The contributions of the thesis include a novel cutter-workpiece engagement calculation algorithm, a five-axis flank milling cutting mechanics model, two methods of optimizing feed rates for impeller machining tool paths and a new five-axis chatter stability algorithm. A semi-discrete, solid-modeling-based method of obtaining cutter-workpiece engagement (CWE) maps for five-axis flank milling with tapered ball-end mills is developed. It is compared against a benchmark z-buffer CWE calculation method, and is found to generate more accurate maps. A cutting force prediction model for five-axis flank milling is developed. This model is able to incorporate five-axis motion, serrated, variable-pitch, tapered, helical ball-end mills and irregular cutter-workpiece engagement maps. Simulated cutting forces are compared against experimental data collected with a rotating dynamometer. Predicted X and Y forces and cutting torque are found to have a reasonable agreement with the measured values. Two offline methods of optimizing the linear and angular feeds for the five-axis flank milling of impellers are developed. Both offer a systematic means of finding the highest feed possible, while respecting multiple constraints on the process outputs. In the thesis, application of these algorithms is shown to reduce the machining time for an impeller roughing tool path. Finally, a chatter stability algorithm is introduced that can be used to predict the stability of five-axis flank milling operations with general cutter geometry and irregular cutter-workpiece engagement maps. Currently, the new algorithm gives chatter stability predictions suitable for high speed five-axis flank milling. However, for low-speed impeller machining, these predictions are not accurate, due to the process damping that occurs in the physical system. At the time, this effect is difficult to model and is beyond the scope of the thesis.

This thesis presents models and algorithms necessary to simulate the five-axis flank milling of jet-engine impellers in a virtual environment. The impellers are used in the compression stage of the engine and are costly, difficult to machine, and time-consuming to manufacture. To improve the productivity of the flank milling operations, a procedure to predict and optimize the cutting process is proposed. The contributions of the thesis include a novel cutter-workpiece engagement calculation algorithm, a five-axis flank milling cutting mechanics model, two methods of optimizing feed rates for impeller machining tool paths and a new five-axis chatter stability algorithm. A semi-discrete, solid-modeling-based method of obtaining cutter-workpiece engagement (CWE) maps for five-axis flank milling with tapered ball-end mills is developed. It is compared against a benchmark z-buffer CWE calculation method, and is found to generate more accurate maps. A cutting force prediction model for five-axis flank milling is developed. This model is able to incorporate five-axis motion, serrated, variable-pitch, tapered, helical ball-end mills and irregular cutter-workpiece engagement maps. Simulated cutting forces are compared against experimental data collected with a rotating dynamometer. Predicted X and Y forces and cutting torque are found to have a reasonable agreement with the measured values. Two offline methods of optimizing the linear and angular feeds for the five-axis flank milling of impellers are developed. Both offer a systematic means of finding the highest feed possible, while respecting multiple constraints on the process outputs. In the thesis, application of these algorithms is shown to reduce the machining time for an impeller roughing tool path. Finally, a chatter stability algorithm is introduced that can be used to predict the stability of five-axis flank milling operations with general cutter geometry and irregular cutter-workpiece engagement maps. Currently, the new algorithm gives chatter stability predictions suitable for high speed five-axis flank milling. However, for low-speed impeller machining, these predictions are not accurate, due to the process damping that occurs in the physical system. At the time, this effect is difficult to model and is beyond the scope of the thesis.

This thesis presents models and algorithms necessary to simulate the five-axis flank milling of jet-engine impellers in a virtual environment. The impellers are used in the compression stage of the engine and are costly, difficult to machine, and time-consuming to manufacture. To improve the productivity of the flank milling operations, a procedure to predict and optimize the cutting process is proposed. The contributions of the thesis include a novel cutter-workpiece engagement calculation algorithm, a five-axis flank milling cutting mechanics model, two methods of optimizing feed rates for impeller machining tool paths and a new five-axis chatter stability algorithm. A semi-discrete, solid-modeling-based method of obtaining cutter-workpiece engagement (CWE) maps for five-axis flank milling with tapered ball-end mills is developed. It is compared against a benchmark z-buffer CWE calculation method, and is found to generate more accurate maps. A cutting force prediction model for five-axis flank milling is developed. This model is able to incorporate five-axis motion, serrated, variable-pitch, tapered, helical ball-end mills and irregular cutter-workpiece engagement maps. Simulated cutting forces are compared against experimental data collected with a rotating dynamometer. Predicted X and Y forces and cutting torque are found to have a reasonable agreement with the measured values. Two offline methods of optimizing the linear and angular feeds for the five-axis flank milling of impellers are developed. Both offer a systematic means of finding the highest feed possible, while respecting multiple constraints on the process outputs. In the thesis, application of these algorithms is shown to reduce the machining time for an impeller roughing tool path. Finally, a chatter stability algorithm is introduced that can be used to predict the stability of five-axis flank milling operations with general cutter geometry and irregular cutter-workpiece engagement maps. Currently, the new algorithm gives chatter stability predictions suitable for high speed five-axis flank milling. However, for low-speed impeller machining, these predictions are not accurate, due to the process damping that occurs in the physical system. At the time, this effect is difficult to model and is beyond the scope of the thesis. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

A new method and mechanism for generating non-uniform, or distorted, aircraft engine inlet flow is being developed in order to account for dynamic changes during the creation and propagation of the distortion. Total pressure distortions occur in gas turbine engines when the incoming flow is disturbed. Dynamic total pressure changes may happen slowly, or may occur very rapidly. The disturbance of the incoming flow can change engine operating characteristics, including lowering the surge limit and creating High Cycle Fatigue incidents. In order to create a distorted flow with dynamic characteristics, a mechanism must be developed that when actuated, can change the distortion pattern and intensity with respect to time. This work covers the initial design of both the distorting and actuating device. The design chosen is a low force design that is practically independent of flow forces. This allows the system to be easily sized for all flow conditions. The study also includes developing the working design into an overall prototype. Testing is also performed to validate the design as the most advantageous choice. / Master of Science

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Aviation’s share of total global carbon emissions has been on the rise as both the decarbonization of other industries and the number of flights has increased. Ammonia as a jet fuel has been receiving attention as a potential carbon free energy storage pathway, both as a fuel and as a carrier of hydrogen. Utilizing ammonia as a fuel requires energy intensive processes making this pathway a compromise specifically intended for power generation purposes that cannot directly use sustainable energy. It is pertinent to understand the cost of realizing ammonia’s advantages as a fuel in the hard to decarbonize industry of aviation. Thermodynamic and Propulsion analysis, run in python and validated by public data, was performed to produce baseline data based loosely on the CFM Leap-1B engine. Modeling was then performed using ammonia, hydrogen, and percentages of cracked ammonia to compare to Jet A. Results show a drop in SFC and a gain in efficiency of 64.72% and 3.68% for hydrogen, respectively, and an increase of 121.7% and 5.08% for ammonia, respectively. Finally, cracked ammonia was used as a fuel while including the effects of heat offtake from the combustion chamber taken to crack the ammonia. The results show an increase in SFC with low and high cracking efficiencies, while revealing that there is a desirable cracking efficiency between 15.5 and 90% where SFC is at a minimum. Out of the 5 cases evaluated, 84.95% cracking resulted in the lowest SFC with a 145.61% increase from Jet A and a 10.8% increase from Ammonia. Finally, a payload diagram reveals the effect of changing fuels on a 737 MAX 8, with Ammonia and Hydrogen dropping the MPL range by around 67 and 81%, respectively, but still greatly outpacing current electric planes.