Master of Science, University of Akron, 0, Electrical Engineering

This thesis investigates the possibility of generating electricity using wind power created by moving traffic at various locations. An energy harvesting system, which could extract the vehicle-induced turbulence energy to power up the low-consumption LED lighting from a self-feeding highway, could be a better solution for the grid-independent lighting system that needs to be installed along the highway that is far away from the major city. This thesis presents the design of a small-scale low starting-speed wind turbine system that can accept wind in any direction. Although many efforts have been made to predict the amount of energy generated by moving vehicles, a very limited number of these efforts have focused on modeling the moving traffic to accurately estimate the amount of energy that it generates. In this thesis, the traffic conditions and vehicle samples are simulated in detail. Based on the generated turbulence, the estimated power is calculated. Also, the numerical modeling for the energy harvesting system is discussed. Moreover, the methods used in the energy harvesting system (including loads, wind turbine, and generator), along with the CFD analysis of different vehicle models and the wind turbine system including LED lighting are also discussed in this thesis. In conclusion, the generated power along the chosen highway with the real traffic data from the design system is sufficient for the use of LED traffic lighting during the nighttime which is around 10 hours.

Committee: Yilmaz Sozer (Advisor); Malik E. Elbuluk (Committee Member); J. Alexis De Abreu García (Committee Member) Subjects: Electrical Engineering; Engineering

Doctor of Philosophy, The Ohio State University, 2021, Aerospace Engineering

Gas turbine performance is highly dependent on turbine inlet temperature, which often exceeds the working limitations of the materials involved. Film cooling is a widely used technology enabling highly efficient gas turbine cycles, where relatively cold air is injected as a film on the airfoil surfaces protecting the airfoils from the hot combustion gasses. Film cooled turbines exist in highly unsteady environments due to interactions between stationary and rotating components, and film cooling further complicates the flow. There is limited understanding of the unsteady nature of film cooling flows, resulting in limited ability to predict heat transfer and metal temperature on the components of a gas turbine. The goal of this work is to increase understanding of turbine cooling technology by examining time-accurate and time-averaged behaviors of the cooling flows. This dissertation incorporates experimental and computational analysis of pressure and heat transfer on an industry scale high-pressure turbine stage. Experimental measurements of pressure and heat transfer were performed on a turbine stage installed in the Turbine Test Facility at the Gas Turbine Laboratory. This facility is uniquely equipped to examine unsteady pressure and heat transfer on turbine stages operating at design corrected conditions. Heat transfer measurements are compared for multiple different cooling configurations on the rotating airfoils. Data are analyzed on time-averaged and time-resolved bases, and the results highlight cooling benefit differences among the various cooling hole shapes and coolant flow rates. Computational models of the turbine stage are also employed with steady and unsteady RANS modeling techniques. Experimental data are used for boundary conditions in the computational models as well as to evaluate the accuracy of the models. Comparisons of experimental and steady computations of film cooled turbines often result in poor agreement due to the complexity of film co (open full item for complete abstract)

Committee: Randall Mathison PhD (Advisor); Sandip Mazumder PhD (Committee Member); Jeffrey Bons PhD (Committee Member); Michael Dunn PhD (Committee Member) Subjects: Aerospace Engineering; Experiments; Mechanical Engineering

Master of Science in Mechanical Engineering (MSME), Wright State University, 2019, Mechanical Engineering

A primary source of periodic unsteadiness in low-pressure turbines is the wakes shed from upstream blade rows due to the relative motion between adjacent stators and rotors. These periodic perturbations can affect boundary layer transition, secondary flow, and loss generation. In particular, for high-lift front-loaded blades, the secondary flowfield is characterized by strong three-dimensional vortical structures. It is important to understand how these flow features respond to periodic disturbances. A novel approach was taken to generate periodic unsteadiness which captures some of the physics of turbomachinery wakes. Using stationary pneumatic devices, pulsed jets were used to generate disturbances characterized by velocity deficit, elevated turbulence, and spanwise vorticity. Prior to application in a turbine flow environment, the concept was explored in a small developmental wind tunnel using a single device. The disturbance flowfield for different input settings was measured using hot-film anemometry and Particle Image Velocimetry. Insight was also garnered on how to improve later design iterations. With an array of devices installed upstream of a linear cascade of high-lift front-loaded turbine blades, settings were found which produced similar disturbances at varying frequencies that periodically impinged upon the leading-edge region. These settings were used to conduct an in-passage secondary flow study using high-speed Stereoscopic Particle Image Velocimetry. Results demonstrated the application of the periodic unsteadiness generator but found minor changes to the passage vortex. The vortex rotational strength decreased, and migration increased with increased perturbation frequency. Fourier analyses found the PV to be responsive at the actuation frequency with phase-locked ensemble-averaged data revealing that the disturbance periodically caused the PV to lose rotational strength. However, at the tested discrete frequencies, the vortex did not become locked (open full item for complete abstract)

Committee: Mitch Wolff Ph.D. (Advisor); Rolf Sondergaard Ph.D. (Committee Member); Christopher Marks Ph.D. (Committee Member) Subjects: Aerospace Engineering; Engineering; Experiments; Fluid Dynamics; Mechanical Engineering

Master of Science in Mechanical Engineering (MSME), Wright State University, 2018, Mechanical Engineering

Various approaches have been used to shape the geometry at the junction of the endwall and the blade profile in high-lift low-pressure turbine passages in order to reduce the endwall losses. This thesis will detail the workflow to produce an optimized non-axisymmetric endwall contour design for a front-loaded high-lift research turbine profile. Validation of the workflow was performed and included a baseline planar and test contour case for a future optimization study. Endwall contours were defined using a series of Bezier curves across the passage to create a smooth surface. A parametric based approach was used to develop the test contour shape with a goal of directing incoming endwall flow at the leading edge towards the suction side of the blade. A commercial RANS flow solver was used to model the flow through the passage. The test contour performance was measured in a low-speed linear cascade wind tunnel to verify that the numerical tools adequately captured the necessary endwall flow physics. The numerical model showed excellent agreement of total pressure loss and endwall flow structure compared with experimental measurements. Utilizing the validated workflow, the grid size, mesh deformation method, and commercial RANS flow solver, previously determined to be adequate, were used to optimize the endwall and gave confidence that the optimized contour would perform well experimentally. A genetic algorithm was used to optimize the endwall and to improve the total pressure loss characteristics. Experimental measurements for the final optimized endwall were obtained in the low-speed wind tunnel. Comparisons between the planar endwall, test case endwall, and optimized endwall shapes were made to show how different shapes affect the flowfield. The test case endwall was found to reduce the losses associated with the passage vortex, while the optimized endwall reduced losses associated with the suction side corner separation vortex.

Committee: Mitch Wolff Ph.D. (Advisor); Christopher Marks Ph.D. (Committee Member); Rolf Sondergaard Ph.D. (Committee Member) Subjects: Aerospace Engineering; Fluid Dynamics; Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2016, Mechanical Engineering

An experiment was performed at The Ohio State University Gas Turbine Laboratory for a film-cooled high-pressure turbine stage operating at design-corrected conditions, with variable rotor and aft purge cooling flow rates. Several distinct experimental programs are combined into one experiment and their results are presented. Pressure and temperature measurements in the internal cooling passages that feed the airfoil film cooling are used as boundary conditions in a model that calculates cooling flow rates and blowing ratio out of each individual film cooling hole. The cooling holes on the suction side choke at even the lowest levels of film cooling, ejecting more than twice the coolant as the holes on the pressure side. However, the blowing ratios are very close due to the freestream massflux on the suction side also being almost twice as great. The highest local blowing ratios actually occur close to the airfoil stagnation point as a result of the low freestream massflux conditions. The choking of suction side cooling holes also results in the majority of any additional coolant added to the blade flowing out through the leading edge and pressure side rows. A second focus of this dissertation is the heat transfer on the rotor airfoil, which features uncooled blades and blades with three different shapes of film cooling hole: cylindrical, diffusing fan shape, and a new advanced shape. Shaped cooling holes have previously shown immense promise on simpler geometries, but experimental results for a rotating turbine have not previously been published in the open literature. Significant improvement from the uncooled case is observed for all shapes of cooling holes, but the improvement from the round to more advanced shapes is seen to be relatively minor. The reduction in relative effectiveness is likely due to the engine-representative secondary flow field interfering with the cooling flow mechanics in the freestream, and may also be caused by shocks and other compr (open full item for complete abstract)

Committee: Randall Mathison (Advisor); Michael Dunn (Committee Member); Sandip Mazumder (Committee Member); Jeffrey Bons (Committee Member) Subjects: Aerospace Engineering; Engineering; Mechanical Engineering

PhD, University of Cincinnati, 2014, Engineering and Applied Science: Aerospace Engineering

An annular combustor is one of the popular configurations of a modern gas turbine combustor. Since the swirlers are arranged as side-by-side in an annular combustor, the swirling flow interaction should be considered for the design of an annular gas turbine combustor. The focus of this dissertation is to investigate the aerodynamics and the combustion of a multiple-swirler array which features the swirling flow interaction. A coaxial counter-rotating radial-radial swirler was used in this work. The effects of confinement and dome recession on the flow field of a single swirler were conducted for understanding the aerodynamic characteristic of this swirler. The flow pattern generated by single swirler, 3-swirler array, and 5-swirler array were evaluated. As a result, the 5-swirler array was utilized in the remaining of this work. The effects of inter-swirler spacing, alignment of swirler, end wall distance, and the presence of confinement on the flow field generated by a 5-swirler array were investigated. A benchmark of aerodynamics performance was established. A phenomenological description was proposed to explain the periodically non-uniform flow pattern of a 5-swirler array. The non-reacting spray distribution measurements were following for understanding the effect of swirling flow interaction on the spray distribution issued out by a 5-swirler array. The spray distribution from a single swirler/ fuel nozzle was measured and treated as a reference. The spray distribution from a 5-swriler array was periodically non-uniform and somehow similar to what observed in the aerodynamic result. The inter-swirler spacing altered not only the topology of aerodynamics but also the flame shape of a 5-swirler array. As a result, the distribution of flame shape strongly depends on the inter-swirler spacing.

Committee: San-Mou Jeng Ph.D. (Committee Chair); Shanwu Wang Ph.D. (Committee Member); Awatef Hamed Ph.D. (Committee Member); Milind Jog Ph.D. (Committee Member); Jongguen Lee Ph.D. (Committee Member) Subjects: Aerospace Materials

Master of Science (M.S.), University of Dayton, 2014, Aerospace Engineering

A significant design concern for turbomachinery parts is forced vibrational response due to unsteady pressure fields. Shortened component lives, increased maintenance costs, and catastrophic engine failure can result due to unmitigated vibrational stresses. Geometry changes, increased airfoil count and wall thickness, and the inclusion of damping systems are a few of the current strategies employed by designers in order to move modal frequencies out of the engine running range or reduce the vibrational stresses on the airfoil. However, these techniques have a negative impact on performance, system weight, and/or life cycle cost. The focus of the study presented here was to investigate the reaction between the blade and downstream vane of the stage-and-a-half High Impact Technologies (HIT) Research Turbine via CFD analysis and experimental data. Code Leo—a Reynolds-Averaged Navier-Stokes (RANS) flow solver with the two-equation Wilcox 1998 k-ω turbulence model—was used as the numerical analysis tool for comparison for all of the experiments conducted, which includes two- and three-dimensional geometries and both time-averaged and time-accurate simulations. The rigorous blade and downstream vane interaction study was accomplished by first testing the midspan and quarter-tip two-dimensional geometries of the blade in a linear transonic cascade. The effects of varying the incidence angle and pressure ratio on the pressure distribution were captured both numerically and experimentally. This was used during the stage-and-one-half post-test analysis to confirm that the target corrected speed and pressure ratio were achieved. Then, in a full annulus facility, the first vane itself was tested in order to characterize the flow field exiting the vane that would be provided to the blade row during the rotating experiments. Finally, the full stage-and-a-half Research Turbine was tested in the full annulus cascade with a data resolution not seen in any studies to date. A rigorous (open full item for complete abstract)

Committee: Aaron Altman (Committee Chair); John Clark (Advisor); Markus Rumpfkeil (Committee Member); William Copenhaver (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering

Master of Science in Mechanical Engineering, Cleveland State University, 2013, Fenn College of Engineering

The purpose of this thesis is to document the impact of incidence angle and Reynolds number variations on the 3-D flow field and midspan loss and turning of a 2-D section of a variable-speed power-turbine (VSPT) rotor blade. Aerodynamic measurements were obtained in a transonic linear cascade at NASA Glenn Research Center in Cleveland, OH. Steady-state data were obtained for ten incidence angles ranging from +15.8&00B0; to -51.0&00B0;. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12 &00D7; 10^5 to 2.12 &00D7; 10^6. Data were obtained at the design exit Mach number of 0.72 and at a reduced exit Mach number of 0.35 as required to achieve the lowest Reynolds number. Midspan total-pressure and exit flow angle data were acquired using a five-hole pitch/yaw probe surveyed on a plane located 7.0 percent axial-chord downstream of the blade trailing edge plane. The survey spanned three blade passages. Additionally, three-dimensional half-span flow fields were examined with additional probe survey data acquired at 26 span locations for two key incidence angles of +5.8&00B0; and -36.7&00B0;. Survey data near the endwall were acquired with a three-hole boundary-layer probe. The data were integrated to determine average exit total-pressure and flow angle as functions of incidence and flow conditions. The data set also includes blade static pressures measured on four spanwise planes and endwall static pressures.

Committee: Mounir Ibrahim PhD (Committee Chair); Miron Kaufman PhD (Committee Member); Ralph Volino PhD (Committee Member) Subjects: Aerospace Engineering; Mechanical Engineering

Master of Science, The Ohio State University, 2010, Aeronautical and Astronautical Engineering

A new turbine research facility at The Ohio State University Aeronautical and Astronautical Research Lab has been constructed. The purpose of this facility is to re-create deposits on the surface of actual aero-engine Nozzle Guide Vane (NGV) hardware in an environment similar to what the hardware was designed for. This new facility is called the Turbine Reacting Flow Rig (TuRFR). The TuRFR provides air at temperatures up to 1200 °C and at inlet Mach numbers comparable to those found in an actual turbine (~0.1). Several validation studies have been undertaken which prove the capabilities of the TuRFR. These studies show that the temperature entering the NGV cascade is uniform, and they demonstrate the capability to provide film cooling air to the NGV cascade at flow rates and density ratios comparable to the NGV design. Deposition patterns have also been created on the surface of actual NGV hardware. Deposition was created at different flow temperatures, and it was found that deposition levels decrease with decreasing gas temperature. Also, film cooling levels were varied from 0% film cooling to 4% film cooling. It was found that with increased rates of film cooling deposition decreased. With the TuRFR capabilities demonstrated, research on the effects of deposition on the aerodynamic performance of the NGV hardware was conducted. Integrated non-dimensional total pressure loss values were calculated in an exit Rec range of 0.2x106 to 1.7x106 for a deposit roughened NGV cascade and a smooth cascade. The data suggests that deposition causes increased losses across the NGV cascade and possibly earlier transition. The data also suggests a possible region of separated flow in the NGV cascade which disappears at higher exit Reynolds numbers. These results are similar to those found in the literature.

Committee: Jeffrey Bons PhD (Advisor); James Gregory PhD (Committee Member); Ali Ameri PhD (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2009, Aeronautical and Astronautical Engineering

This is the first 3-D unsteady RANS simulation of a highly loaded transonicturbine stage and results are compared to steady calculations and experiments. A low Reynolds number k-ε turbulence model is employed to provide closure for the RANS system. Phase-lag is used in the tangential direction to account for stator-rotor interaction. Due to the highly loaded characteristics of the stage, inviscid effects dominate the flowfield downstream of the rotor leading edge minimizing the effect of segregation to the leading edge region of the rotor blade. Unsteadiness was observed at the tip surface that results in intermittent 'hot spots'. It is demonstrated that unsteadiness in the tip gap is governed by both inviscid and viscous effects due to shock-boundary layer interaction and is not heavily dependent on pressure ratio across the tip gap. This is contrary to published observations that have primarily dealt with subsonic tip flows. The high relative Mach numbers in the tip gap lead to a choking of the leakage flow that translates to a relative attenuation of losses at higher loading. The efficacy of a new tip geometry is discussed to minimize heat flux at the tip while maintaining choked conditions. Simulated heat flux and pressure on the blade and hub agree favorably with experiment and literature. The time-averaged simulation provides a more conservative estimate of heat flux than the steady simulation. The shock structure formed due to stator-rotor interaction is analyzed. A preprocessor has also been developed as a conduit between the unstructured multi-block grid generation software GridPro and the CFD code TURBO.

Committee: Jen-Ping Chen PhD (Advisor); Ali Ameri PhD (Committee Member); Meyer Benzakein PhD (Committee Member); Jeffrey Bons PhD (Committee Member); Henry Busby PhD (Committee Member) Subjects: Engineering; Physics

Master of Science, The Ohio State University, 2009, Aeronautical and Astronautical Engineering

Detailed pressure and velocity measurements were acquired at Rec = 20,000 with 3% inlet free stream turbulence intensity to study the effects of position, phase and forcing frequency of vortex generator jets employed on an aft-loaded low-pressure turbine blade in the presence of impinging wakes. The L1A blade has a design Zweifel coefficient of 1.34 and a suction peak at 58% axial chord, making it an aft-loaded pressure distribution. At this Reynolds number, the blade exhibits a non-reattaching separation region beginning at 60% axial chord under steady flow conditions without upstream wakes. Wakes shed by an upstream vane row are simulated with a moving row of cylindrical bars at a flow coefficient of 0.91. Impinging wakes thin the separation zone and delay separation by triggering transition in the separated shear layer, although the flow does not reattach. Instead, at sufficiently high forcing frequencies, a new time-mean separated shear layer position is established which begins at approximately 72%Cx. Reductions in area-averaged wake total pressure loss of more than 75% were documented. One objective of this study was to compare pulsed flow control using two rows of discrete vortex generator jets (VGJs). The VGJs are located at 59%Cx, approximately the peak Cp location, and at 72%Cx. Effective separation control was achieved at both locations. In both cases, wake total pressure loss decreased 35% from the wake only level and the shape of the Cp distribution indicates that the cascade recovers its high Reynolds number (attached flow) performance. The most effective separation control was achieved when actuating at 59%Cx where the VGJ disturbance dominates the dynamics of the separated shear layer, with the wake disturbance assuming a secondary role only. On the other hand, when actuating at 72%Cx, the efficacy of VGJ actuation is derived from the relative mean shear layer position and jet penetration. When the pulsed jet actuation (25% duty cycle) was initiated (open full item for complete abstract)

Committee: Jeffrey Bons PhD (Advisor); James Gregory PhD (Committee Member) Subjects: Aerospace Materials; Engineering; Fluid Dynamics; Mechanical Engineering

Master of Science, The Ohio State University, 2003, Aeronautical and Astronautical Engineering

This paper describes measurements obtained for a state of the art one and one-half stage turbine with emphasis on the experimental results. As part of the experimental effort, the position of the HPT vane was clocked relative to the downstream LPT vane to determine the influence of vane clocking on the unsteady pressure loadings on the LPT vane and the HPT blade. In addition, the axial location of the HPT vane relative to the HPT blade was changed to investigate the combined influence of vane/blade spacing and clocking on the unsteady pressure loading. In recent years, other investigators have also examined clocking and vane/blade spacing (but not within the same data set) using different turbine stages and those works will be put into perspective with this work. Time-averaged and time-accurate surface pressure will be presented for several spanwise locations on the vanes and blade. Results were obtained at four different clocking positions for the HPT vane and for two different vane/blade axial spacings at three (of the four) clock positions. This thesis also describes the heat transfer results for a measurement program utilizing the same state of the art one and one-half stage transonic turbine. Both aerodynamic data (surface pressure data) and heat transfer data were obtained at the 50% span location on the HPT vane, HPT blade, and LPT vane. The heat flux data are normalized and presented as time-averaged Stanton numbers and compared to flat plate correlations. Time accurate Stanton numbers are also presented for selected locations on the HPT blade and on the blade outer air seal.

Committee: Michael Dunn (Advisor) Subjects: Engineering, Aerospace

Master of Science (M.S.), University of Dayton, 2010, Aerospace Engineering

An investigation into wake and solid blockage effects of Vertical-Axis Wind Turbines (VAWTs) in closed test-section wind tunnel testing is described. Static wall pressures have been used to derive velocity increments along a wind tunnel test-section which in-turn are applied to provide evidence of wake interference characteristics of rotating bodies interacting within this spatially restricted domain. Vertical-axis wind turbines present a unique aerodynamic obstruction in wind tunnel testing whose blockage effects have not been extensively investigated.The flow-field surrounding these wind turbines is asymmetric, periodic, unsteady, separated and highly turbulent. Static pressure measurements are taken along a test-section sidewall to provide a pressure signature of the test models under varying rotor tip-speed ratios (freestream conditions and model RPM's). To provide some guidance on the scaling of the combined effects of wake and solid blockage, wake characteristics and VAWT performance produced by the same vertical-axis wind turbine concept have been tested at different physical scales in two different wind tunnels. This investigation provides evidence of the effects of large wall interactions and wake propagation caused by these models at well below generally accepted standard blockage figures.

Committee: Aaron Altman PhD (Committee Chair); Jewel Barlow PhD (Committee Member); Eric Lang PhD (Committee Member) Subjects: Aerospace Materials; Engineering; Experiments; Fluid Dynamics; Mechanical Engineering