A typical approach to optimize wind turbine blades separates the airfoil shape design from the blade planform design. This approach is sequential, where the airfoils along the blade span are pre-selected or optimized and then held constant during the blade planform optimization. In contrast, integrated blade design optimizes the airfoils and the blade planform concurrently and thereby has the potential to reduce cost of energy (COE) more than sequential design. Nevertheless, sequential design is commonly performed because of the ease of precomputation, or the ability to compute the airfoil analyses prior to the blade optimization. This research investigates two integrated blade design approaches, the precomputational and free-form methods, that are compared to sequential blade design. The first approach is called the precomputational method because it maintains the ability to precompute, similar to sequential design, and allows for partially flexible airfoil shapes. This method compares three airfoil analysis methods: a panel method (XFOIL), a Reynolds-averaged Navier-Stokes computational fluid dynamics method (RANS CFD), and using wind tunnel data. For each airfoil analysis method, there are two airfoil parameterization methods: the airfoil thickness-to-chord ratio and blended airfoil family factor. The second approach is called the free-form method because it allows for fully flexible airfoil shapes, but no longer has the ease of precomputation as the airfoil analyses are performed during the blade optimization. This method compares XFOIL and RANS CFD using the class-shape-transformation (CST) method to parameterize the airfoil shapes. This study determines if the precomputational method can capture the majority of the benefit from integrated design or if there is a significant additional benefit from the free-form method. Optimizing the NREL 5-MW reference turbine shows that integrated design reduce COE significantly more than sequential design. The precomputational method improved COE more than sequential design by 1.6%, 2.8%, and 0.7% using the airfoil thickness-to-chord ratio, and by 2.2%, 3.3%, and 1.4% using the blended airfoil family factor when using XFOIL, RANS CFD, and wind tunnel data, respectively. The free-form method improved COE more than sequential design by 2.7% and 4.0% using the CST method with XFOIL and RANS CFD, respectively. The additional flexibility in airfoil shape reduced COE primarily through an increase in annual energy production. The precomputational method captures the majority of the benefit of integrated design (about 80%) for minimal additional computational cost and complexity, but the free-form method provides modest additional benefits if the extra effort is made in computational cost and development time.

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Pressure gain combustion is a form of combustion that uses pressure waves to transfer energy and generate a rise in total pressure during the combustion process. Pressure gain combustion shows potential to increase the cycle efficiency of conventional gas turbine engines if used in place of the steady combustor. However, one of the challenges of integrating pressure gain combustion into a gas turbine engine is that a turbine driven by pulsing flow experiences a decrease in efficiency. The interaction of pressure pulses with a turbine was investigated to gain physical insights and to provide guidelines for designing turbines to be driven by pulsing flow. An experimental rig was built to compare steady flow with pulsing flow. Compressed air was used in place of combustion gases; pressure pulses were created by rotating a ball valve with a motor. The data showed that a turbine driven by full annular pressure pulses has a decrease in turbine efficiency and pressure ratio. The average decrease in turbine efficiency was 0.12 for 10 Hz, 0.08 for 20 Hz, and 0.04 for 40 Hz. The turbine pressure ratio, defined as the turbine exit total pressure divided by the turbine inlet total pressure, ranged from 0.55 to 0.76. The average decrease in turbine pressure ratio was 0.082 for 10 Hz, 0.053 for 20 Hz, and 0.064 for 40 Hz. The turbine temperature ratio and specific turbine work were constant. Pressure pulse amplitude, not frequency, was shown to be the main cause for the decrease in turbine efficiency. Computational fluid dynamics simulations were created and were validated with the experimental results. Simulations run at the same conditions as the experiments showed a decrease in turbine efficiency of 0.24 for 10 Hz, 0.12 for 20 Hz, and 0.05 for 40 Hz. In agreement with the experimental results, the simulations also showed that pressure pulse amplitude is the driving factor for decreased turbine efficiency and not the pulsing frequency. For a pulsing amplitude of 86.5 kPa, the efficiency difference between a 10 Hz and a 40 Hz simulation was only 0.005. A quadratic correlation between turbine efficiency and corrected pulse amplitude was presented with an R-squared value of 0.99. Incidence variation was shown to cause the change in turbine efficiency and a correlation between corrected incidence and corrected amplitude was established. The turbine geometry was then optimized for pulsing flow conditions. Based on the optimization results and observations, design recommendations were made for designing turbines for pulsing flow. The first design recommendation was to weight the design of the turbine toward the peak of the pressure pulse. The second design recommendation was to consider the range of inlet angles and reduce the camber near the leading edge of the blade. The third design recommendation was to reduce the blade turning to reduce the wake caused by pulsing flow. A new turbine design was created and tested following these design recommendations. The time-accurate validation simulation for a 10 Hz pressure pulse showed that the new turbine decreased the entropy generation by 35% and increased the efficiency by 0.04 (5.4%).

This thesis describes selection and shows calibration of material model, capable of describing cyclic softening of material. Stress-strain FEM analysis of circumferential blade attachment for last section of rotor blades of steam turbine is performed, expected lifetime of existing attachment is evaluated. Multi-parameter optimization of new-shape attachment was done, resulting in dimensions for new-shape attachment with longer lifetime. Improvements in strain amount in comparison with existing attachment were evaluated and possible RPM increase of turbine with new attachment type was calculated.