Thesis (M.S.)--Brigham Young University. Dept of Mechanical Engineering, 2007. / Includes bibliographical references (p. 112-114).

Thesis (M. Eng.)--Carleton University, 1988. / Also available in electronic format on the Internet.

Techn. Universiẗat, Diss., 2005--München.

One of the common failure modes of the diesel engine turbochargers is high-cycle fatigue of the turbine-wheel blades. Mistuning of the blades due to the casting process is believed to contribute to this failure mode. A laser vibrometer is used to characterize mistuning for a population of turbine wheels through the analysis of the blade-response to piezo-speaker induced noise. The turbine-wheel design under investigation is radial and is typically used in 6-12L diesel engine applications. FRFs and resonance frequencies are reviewed and summarized. The study includes test results for a paddle wheel that represents a perfectly tuned system and acts as a reference. A discrete mass-spring model is developed for the paddle wheel and the model suitability is tested against measured data. Density randomization is applied to model mistuning in the turbine wheels. Frequency mistuning and relative amplitude modelling for blade modes is found in good agreement with the data, however the mass-spring model over-predicts amplitude-amplification factors for a population of radial-turbine wheels, especially with regard to hub-dominant modes. A continuous twisted-blade model is developed in Matlab using finite-element techniques. Experimental data is shown to have good agreement with the twisted-blade model. Whitehead’s maximum amplitude-amplification prediction using RMS value for a tuned amplitude value is calculated, and the turbine-wheel response is found to fit within the theoretical limit. Different mistuning patterns are studied using the twisted-blade model. Maximum and minimum response patterns are identified and recommended.

This investigation deals with the vibration problem of a rotating shrouded bladed disc and with the dynamic stresses of blades and packets of turbine blades. The wave propagation technique in periodic structures is introduced into the finite element method to reduce the overall number of degrees of freedom. The application of wave propagation technique to discs, disc-blades and shrouded bladed disc results in a small size eigenvalue problem which is easily solved to obtain the frequencies and mode shapes of these assemblies under the effects of rotation, disc thickness variations, disc flexibility and other design parameters. The numerical integration is used to evaluate the integrals of the stiffness and mass matrices of the variable thickness discs. The influence of rotational speeds and other design parameters such as; pretwist angles and stagger angles on the free vibration characteristics of blades, curved beams and packets of blades is studied using finite element method. The results of the natural frequencies are compared with the experimental results and with the results of other investigators. The dynamic stresses of blades and packets of blades are derived from the eigenvectors obtained in the vibration study of these components. The effects of rotational speeds, pretwist angles, stagger angles and shrouding on the dynamic stresses are studied.

The work contained in this thesis covers the design, development and testing of a horizontal axis wind turbine (HAWT) with Sailfoil blades. Included is a brief history of wind turbine technology, its revival, a review of current wind energy developments and a literature survey of previous work on wind turbines with sail type blades. The Sailfoil blade consists of a framework of a leading edge D spar and a rigid trailing edge spar over which is stretched a fabric sock, forming a wing-like surface. The aerodynamic performance theories of HAWTs are described, as is the aerodynamic, structural and mechanical design of a 4 metre diameter, 3 bladed HAWT with Sailfoil blades. A wind turbine test facility was designed and developed for free air testing of wind turbines and is described. Free air tests were carried out on the Sailfoil wind turbine on the test facility to obtain power coefficient versus tip speed ratio curves and power versus wind speed curves for the wind turbine. These are presented and compared to predicted values.

Made available in DSpace on 2014-06-11T19:35:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-10-29Bitstream added on 2014-06-13T20:46:42Z : No. of bitstreams: 1 batista_jc_dr_guara.pdf: 2889755 bytes, checksum: 2777cd1f4225a0232c6281a5ca3d1e00 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho desenvolve um sistema para gerar energia elétrica com caldeira e turbina, para ocupar um nicho de mercado em que os sistemas a vapor existentes não são economicamente viáveis. O sistema utiliza a turbina Tesla que é compatível para essa faixa e não possui pás, podendo operar com vapor saturado fornecido por uma pequena caldeira consumindo lenha. A micro-geração proposta pode levar energia a milhões de brasileiros no campo, onde se dispõe de algum tipo de biomassa. Apesar do baixo custo da turbina Tesla, por ser de simples construção e compacta, e de suas incontáveis possibilidades de aplicação, se desconhece, até então, aplicações comerciais massivas devido ao baixo torque obtido nos protótipos feitos desde 1910 e por essa razão foi modificada. Este trabalho inova ao desenvolver um protótipo da turbina Tesla modificado para fornecer maior torque e ao comparar à turbina Tesla original. Devido à inexistência de equações que descrevem a turbina Tesla, um modelo matemático que permite projetar a turbina Tesla foi desenvolvido e validado por resultados experimentais e de simulação. Testes comparativos com duas turbinas com as mesmas dimensões mostraram que a turbina Tesla modificada apresentou eficiência superior à turbina Tesla original. Desenvolveu-se, também, um protótipo do sistema para micro-geração utilizando a turbina Tesla modificada, caldeira e gerador elétrico. Os custos do sistema e da energia gerada foram comparados com os de outros meios de geração mostrando serem competitivos economicamente para essa faixa de operação. / This work develops a system to generate electric power with boiler and turbine that aims to occupy the niche of the market for which steam systems are not economically viable. The system uses a Tesla turbine, which is compatible to the range of power. Also, it does not have blades, being able to operate with steam delivered by a small boiler fed with wood. The proposed micro-generation system can take energy to millions of Brazilians living in the country, where some type of biomass is available. In despite of the low cost of the Tesla turbine, because it is compact and simple to build, and despite of its uncountable possibilities of applications, massive commercial applications of the technology are not found due to the low torque of the prototypes built since 1910. For this reason, the Tesla turbine was modified. This work is original since it develops a modified Tesla turbine prototype to furnish a higher torque when compared to an original Tesla turbine. Due to the lack of equations that model a Tesla turbine, a mathematical model was developed to allow the design of the Tesla turbine; it was validated by means of experimental and simulating results. The comparative tests with two turbines, with same dimensions, showed that the modified Tesla turbine presents a higher efficiency than the original Tesla turbine. A micro-generation system, using the modified Tesla turbine, boiler and electric generator, was also developed. The costs of the system and of the generated energy were compared with other means of generation and showed to be commercially competitive for that range.

No description available.

No description available.

The temperature of the flow entering a high-pressure turbine stage is inherently non-uniform, as it is produced by several discrete, azimuthally-distributed combustors. In general, however, industrial simulations assume inlet temperature uniformity to simplify the preparation process and reduce computation time. The effects of a non-uniform inlet field on the performance of a commercial, transonic, single-stage, high-pressure, axial turbine with a curved inlet duct have been investigated numerically by performing URANS (Unsteady Reynolds-Averaged Navier-Stokes equations) simulations with the SST (Shear Stress Transport) turbulence model. By adjusting the alignment of the experimentally-based inlet temperature field with respect to the stator vanes, two clocking configurations were generated: a vane-impinging (VI) case , in which each hot streak impinged on a vane; and a mid-pitch (MP) case, in which each hot streak passed between two vanes. In the VI configuration, the hot streaks produced higher time-averaged heat load on the vanes and lower heat load on the blades. As the hot streaks in the VI case passed over the stator vanes, they also spread spanwise due to the actions of the casing passage vortices and the radial pressure gradient; this resulted in a stream entering the rotor with relatively low temperature variations. The hot streaks in the MP case were convected undisturbed past the relatively cool vane section. Relatively high time-averaged enthalpy values were found to occur on the pressure side of the blades in the MP configuration. The non-uniformity of the time-averaged enthalpy on the blade surfaces was lower in the VI configuration. The flow exiting the rotor section was much less non-uniform in the VI case, but differences in calculated efficiency were not significant. / Pratt & Whitney Canada, NSERC