by Shaun Hurley. / Thesis (M.S.C.S.)--Florida Atlantic University, 2011. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2011. Mode of access: World Wide Web. / The study presents a reliability-based fatigue life prediction model for the ocean current turbine rotor blades. The numerically simulated bending moment ranges based on the measured current velocities off the Southeast coast line of Florida over a one month period are used to reflect the short-term distribution of the bending moment ranges for an idealized marine current turbine rotor blade. The 2-parameter Weibull distribution is used to fit the short-term distribution and then used to obtain the long-term distribution over the design life. The long-term distribution is then used to determine the number of cycles for any given bending moment range. The published laboratory test data in the form of an ε-N curve is used in conjunction with the long-term distribution of the bending moment ranges in the prediction of the fatigue failure of the rotor blade using Miner's rule. The first-order reliability method is used in order to determine the reliability index for a given section modulus over a given design life. The results of reliability analysis are then used to calibrate the partial safety factors for load and resistance.

This research focuses on studying the feasibility of placing large wind turbines on deep-ocean platforms. Water tank studies have been conducted using the facilities at Alden Research Laboratories (ARL) on 100:1 scale Tension Leg Platform (TLP) and Spar Buoy (SB) models. Froude scaling was used for modeling the offshore wind turbine designs. Primary components of the platform turbine, tower, and cable attachments were fabricated in ABS plastic using rapid prototyping. A wireless data acquisition system was installed to prevent umbilical data cables from affecting the behavior of the platform when exposed to wave loading. In Phase I testing, Froude-scaled TLP and Spar Buoy models at a 100:1 scale were placed in a water flume and exposed to periodic waves at amplitudes ranging from 0.5 cm - 7.5 cm and frequencies ranging from 0.25 Hz - 1.5 Hz. The testing was conducted on simple tower and turbine models that only accounted for turbine weight at the nacelle. In Phase II testing, emphasis was placed on further testing of the tension leg platform as a more viable design for floating offshore wind turbines. The tension leg platform scale model was improved by adding a disc to simulate drag force incident at the top of the tower, as well as a rotor and blades to simulate the gyroscopic force due to turbine blade rotation at the top of the tower. Periodic wave motions of known amplitude and frequency were imposed on the model to study pitch, heave, roll, surge, sway motions and mooring cable tensions (in Phase II only) using accelerometers, inclinometers, capacitance wave gage, and load cells. Signal analysis and filtering techniques were used to refine the obtained data, and a Fourier analysis was conducted to study the dominant frequencies. Finally, Response Amplitude Operators (RAO's) were plotted for each data set to standardize the results and study the overall trend with respect to changes in wave amplitude and frequency. For Phase I testing, it is shown that surge motion of the platform dominates other motions for both the tension leg platform and spar buoy, and varying tether pretension has little effect on response amplitude operator values. For phase II testing, it was found that the introduction of thrust and gyroscopic forces increases sway and pitch motions as well as upstream tether forces. Coupling effects of pitch motion with roll and sway due to the presence of gyroscopic forces were also seen. The present experimental results can be used to validate the hydrodynamic kernels of linear frequency-domain models, time-domain dynamics models, and computational simulations on floating wind turbines. Numerical analysis and simulations have been conducted in a separate study at WPI. These simulations are comparable to the experimental results.

Ce travail propose l’investigation d’une approche physique 0D/1D modélisant les brûleurs de turbines à gaz, prenant en compte l’évaporation du carburant, la turbulence, la combustion, et permet la représentation de zones de dilution et l’implémentation de modèles de chimie des polluants. Il s’agit de sous-modèles répartis dans des composants assemblables dans un environnement numérique multi-domaines basé sur le formalisme de Bond Graph. Ceci permet, par exemple, l’assemblage de plusieurs volumes ouverts en un tube à flamme, l’ajout d’un compresseur et d’une turbine, ou bien aussi d’intégrer des chaînes de commande afin de représenter un hélicoptère complet. L’originalité de cette thèse réside dans l’application d’un paradigme de combustion 0D, issu d’une approche 3D élaborée chez IFP Energies nouvelles et appliquée avec succès aux moteurs alternatifs ainsi qu’à des turbines à gaz. Le sous-modèle intègre le formalisme de flamme cohérente qui distingue une zone de gaz frais d’une zone de gaz brûlés. Les deux zones sont séparées par une flamme turbulente. Le sous-modèle de tube à flamme décrit la flamme grâce à une synthèse issue de résultats de calculs CFD 3D validés par des expériences. En effet, des résultats de calculs LES d’un brûleur expérimental monophasique ont étés analysés pour caractériser la combustion turbulente prémélangée dans un brûleur à tourbilloneur. Enfin, un secteur de brûleur réel de turbomoteur a été étudié à l’aide de simulations CFD afin d’évaluer la pertinence du modèle de tube à flamme 0D/1D et de guider la modélisation permettant de compléter la nouvelle approche de simulation système des turbines à gaz. / This work investigates a unique 0D/1D physical approach for gas turbine combustor modelling. It accounts for fuel evaporation, turbulence, combustion, and allows to represent dilution stages. Detailed pollutants formation models can also be added. The chosen formalism, based on the Bond Graph theory approach, allows to describe systems organised in a series of submodel components such as a series of open volumes forming a flame tube, or a combustor coupled to a compressor and turbine but they can also be combined with control and regulation devices in order to represent a complete rotorcraft. The essence of the PhD strategy is the application of a 0D combustion paradigm, obtained at IFP Energies nouvelles by formal reduction of 3D approaches for gas turbines. More in details, a new combustion model was developed integrating the Coherent Flame Model (CFM) formalism which allows to distinguish between fresh gases and burned gases separating them with a turbulent flame. The flame tube submodel features a physical description of the flame thanks to thorough understanding given by 3D CFD simulation results validated against experimental measurements. More specifically, LES results corresponding to a single phase test rig were analysed in order to characterise premixed turbulent combustion in a swirl burner. Finally, a real turboshaft combustor sector case was studied by means of CFD simulations to investigate the relevance of the 0D/1D flame tube model and to determine modelling strategies for the completion of the new gas turbine system simulation approach.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Lee Wing Ho. / M.S.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1979. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERONAUTICS. / Vita. / Includes bibliographical references. / Ph.D.

The deregulation of the electric power market introduced a strong element of competition. Power plant operators strive to develop advanced operational strategies to maximize the profitability in the dynamic electric power market. New methodologies for gas turbine power plant operational modeling and optimization are needed for power plant operation to enhance operational decision making, and therefore to maximize power plant profitability by reducing operations and maintenance cost and increasing revenue. In this study, a profit based, lifecycle oriented, and unit specific methodology for gas turbine based power plant operational modeling was developed, with the power plant performance, reliability, maintenance, and market dynamics considered simultaneously. The generic methodology is applicable for a variety of optimization problems, and several applications for operational optimization were implemented using this method. A multiple time-scale method was developed for gas turbine power plants long term generation scheduling. This multiple time-scale approach allows combining the detailed granularity of the day-to-day operations with global (seasonal) trends, while keeping the resulting optimization model relatively compact. Using the multiple timescale optimization method, a profit based outage departure planning method was developed, and the key factors for this profit based approach include power plant aging, performance degradation, reliability deterioration, and the energy market dynamics. A novel approach for gas turbine based power plant sequential preventive maintenance scheduling was also introduced. Finally, methods to evaluate the impact of upgrade packages on gas turbine power plant performance, reliability, and economics were developed, and TIES methodology was applied for effective evaluation and selection of gas turbine power plant upgrade packages.

A 2-D CFD / FEM model to simulate thermal stresses in a turbine blade has been set up using the software FLUENT and FIDAP. The model was validated against the data of Bohn et. al. (1995) and was used to simulate 5 test cases. The numerical model was set up for a single Mark II nozzle guide vane (NGV) and utilised the appropriate boundary conditions for the surrounding flow field. A commercially available software code, FLUENT, was used to resolve the flow field, and heat transfer to the blade. The resulting surface temperature profile was then plotted and used as the boundary conditions in FIDAP (a commercial FEM code) to resolve the temperature and stress profile in the blade. An additional solver within FLUENT essentially superimposes an additional flow field as a result of the NGV vibration in the flow field. The pressure, temperature and heat transfer coefficient distribution, from FLUENT, were compared to those from Bohn et. al. (1995). The model predicted the distributions trends correctly, with an average over-prediction for temperature, of 10 % on the suction side and 6 % on the pressure side. This was restricted to the region from leading edge to 40 % chord on both sides of the blade. The blade temperature and equivalent stress contour trends were also correctly predicted by FIDAP. The blade temperature was over-predicted by and average of 1.7 %, while the equivalent stress magnitude was under-predicted by a worst case of 43 %, but the locations of maximum stress were correctly predicted. The reason for the differences between the stresses predicted by FLUENT / FIDAP and the data given in Bohn et. al. (1995), is believed to be the results of the temperature dependence of the material properties for the blade (ASTM 310 stainless steel), used in the two studies, not being identical. The reasoning behind this argument is because the distribution trends and contour variation, predicted by the model, compared favourably with the data of Bohn et. aI., and only the equivalent stress magnitude differed significantly. This completed the validation of the FLUENT / FIDAP model. The model was used to simulate test cases where temperature (i.e. turbine inlet temperature or TIT), at the model inlet (Le. the pressure inlet boundary in FLUENT), was set up to be time varying. Four simplified cases, viz single shock, multiple shocks, simplified cycle and multiple cycles, and a complex cycle (a mission profile) were simulated. The mission profile represented typical gas turbine operational data. The simulation results showed that stress was proportional to TIT. Changes in TIT were seen at a later time in the stress curve, due to conduction through the blade. Steep TIT changes, such as the shock loads, affected stress later than gentler TIT changes - the simplified and multiple cycles. These trends were consistently seen in the complex cycle. The maximum equivalent stress was plotted against TIT to try and develop a loose law that gives maximum equivalent stress as a function of TIT. A 4th order polynomial was fitted through the maxima and minima of the maximum equivalent stress plot, which gave the maximum and minimum stress as a function of TIT. This function was used calculate the maximum and minimum and mean equivalent stress using the TIT data for the mission profile. Thus, the FLUENT I FIDAP model was successfully validated, used to simulated the test cases and a law relating the equivalent stress as a function of TIT was developed. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2002.

The necessity to develop an automated process for the design of micro-hydro power systems was based on the increasing demand for hydropower as a renewable energy source and to develop cost effective power supplies to rural areas. The application of the formula for the design of these systems is then to simplify the selection of the turbine sizing and is made possible by the similarity laws that exist within turbine and pump families. in addition the sizing of the supply and exhaust piping is also a matter of scaling. No selection process of turbine type is included due to the limitations of cost effectiveness and the category of size into which the turbine was specified. Furthermore. a new approach to turbine design was separately undertaken to satisfy low head and low flow-rate conditions. However, it was only designed up to a cost analysis with no manufacturing having been undertaken. The axial flow turbine. which was most suited for micro-hydro was designed and built as a prototype with a standardized mounting frame. The initial conditions used to generare the velocity vectors and angles were specific to the installation site and used to computationally generate the rotor and stator blades. This required an analysis of the different profiles available as well as research into their design. Once the blade profile stacking had been determined, this was translated into a software program that developed the blades from site-specific initial conditions. However, the design of the blades was interdependent on the dimensioning of the rest of the turbine components and designing these in parallel proved to be an intricate task. With the design complete, the turbine was then installed and testing proceeded with the use of pressure gauges and the results of torque and rpm obtained from a dynamometer. Analysis of the results was undertaken and presented in graphical format with comments on both the design and results. / Thesis (M.Sc.Eng.) -University of Natal, Durban, 2000.

No description available.

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 206-210). Also available via World Wide Web.