Sea water intake structures submerged in the surf zone are used to provide water for cooling processes in large facilities such as power plants and refineries. Structures submerged in the surf zone are subject to large forces from breaking waves. To study these forces induced from realistic sea state conditions, a physical model of an intake structure submerged in the wave breaking zone was constructed and subjected to a wide spectrum of regular and irregular waves. The model structure was designed in a manner so force measurement could be isolated to separate components of the structure. The data of peak forces on the structure was analyzed for correlations with varying irregular wave properties. Using the results of forcing on the structure from regular wave tests, drag and inertia coefficients for use in the Morison equation were determined for each separate component and configuration of the structure. These force coefficients were plotted against various wave properties to analyze correlations with wave conditions. Finally, the force coefficients for the structure were used with the Morison equation and current data from the experiments to successfully model forcing on the structure during irregular wave tests.

The views expressed in this thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government. / The numerical experiments, carried out through the use of a pressure-velocity coupled method to solve the Favre Averaged Navier-Stokes equations, on steady and sinusoidally oscillating flows at five different Keluegan-Carpenter numbers, and three periodicity levels are described. A second-order in time, second-order in space, second-level predictor-corrector finite difference scheme has been used. The solutions were solved by the CFD-ACE program from the CFD Research Corporation. The analysis has produced in-line force coefficients comparable to those obtained experimentally for sinusoidally-oscillating flows.

The majority of commercially available ultrasonic transducers used to excite and measure wave propagation in structures can be coupled only to a free surface. While convenient, this method is likely to excite multiple structural modes, making data interpretation difficult. Furthermore, the many modes excited make predicting the structure’s response a computationally intensive task. Here the dynamic radial displacement induced by a transient radial point load is calculated at more than 230,000 points on the outer surface of a virgin steel pipe to simulate a typical experiment. The radial component of the displacement field is calculated by convolving the Green’s functions of the pipe with the transient load. These functions are calculated on personal computers (in a distributed arrangement) by employing modal summation. The mode shapes are obtained from a Semi-Analytical Finite Element formulation used in conjunction with a separation of variables. The results are presented in a four dimensional animation, providing easier interpretations and insight into how to best select observation points for the detection of defects. The accuracy of the calculated displacements is verified experimentally. Agreement is good when magnitude and phase corrections are incorporated from the frequency response curves of the transducers used.

The objective of this study is to analyze theoretically the laminar film condensation of water vapor flowing on a sphere. For this purpose, the problem was handled by including all of the two-phase boundary layer parameters such as gravity, effect of vapor shear, inertia, energy convection and pressure gradient. For this full two-phase boundary layer system, the boundary layer equations, boundary conditions and the interfacial conditions were first analyzed, and then discretized. A computer program in Mathcad, solving these discretized equations, was written to obtain the velocity and temperature profiles within the condensate, the velocity profiles within the vapor, the condensate film thickness and the local Nusselt number. The effects of pressure gradient, gravity, vapor oncoming velocity and sphere radius on these parameters were examined. By alternating the formulation of the problem, the results for the flow over a horizontal cylinder were obtained. These results were then compared with those for the sphere. Finally, the results for the system with Mercury vapor flowing on a sphere were obtained. All of these results were represented as diagrams and tables, and were discussed at the end of the study.

In this study, a long annulus bonded to a rigid cylinder containing an axisymmetric circumferential crack of width (d-c) at the midplane is considered. The material of the annulus is assumed to be linearly elastic and isotropic. The external surface of the annulus is free of stress. Surfaces of the crack are subject to distributed compressive loads. The Fourier and Hankel transform techniques are used to solve the governing equations which are reduced to a singular integral equation for crack surface displacement derivative. This integral equation is converted to a system of linear algebraic equations which are solved numerically by using Gauss-Lobatto and Gauss-Jacobi quadrature formulas. Then, the stress intensity factors at the edges of the crack are calculated. Results are presented in graphical form.

Local scour around bridge piers can cause serious damages and structural failure to the bridge. Correct prediction of the scour is an important criterion for the engineering design. Though the subject has been investigated for many decades, the theoretical developments have been very limited due to the complicated interaction of three-dimensional flow and the sediment transport. This thesis concerns the flow around a vertical bottom mounted cylinder exposed to currents and is considered as the initial phase of a study towards modeling local scour around vertical bottom-mounted structures. The aim of the present study is to obtain a better understanding of the complex three-dimensional flow and the mechanisms related to the scouring. The study started with the development of a three-dimensional numerical model to simulate flow around cylindrical structures. After validation of the model, the model was applied to investigate flow around an isolated rectangular cylinder. Unsteady flows around cylinders of a square cross section (A/D = 1) and a rectangular cross section (A/D = 2) were simulated to understand the flow properties around a cylinder other than a circular cross section. Three-dimensional flow patterns, pressure distribution, forces on the cylinder and vortex-shedding frequencies were discussed. It was found that the present numerical results generally agree well with the experimental data. Flow around a vertical cylinder mounted on a rigid bed was then investigated by the numerical model. A circular and a square cross sections were considered respectively. Flow structures of horseshoe vortex and the wake vortex which are the major mechanisms leading to the scouring around the base of the vertical cylinder were explored. The bed shear stress distributions that directly affect the scour processes were discussed. Finally the numerical model was applied to study the flow around a submerged square cylinder mounted on a bed, which has significant engineering relevance to the local scour around structures, such as bridge pier foundation itself, or a caisson placed underwater around the pier bottom for scour protection. The numerical calculations were carried out at different cylinder heights to investigate the effect of the cylinder height on the flow properties. It was found that for submerged cylinders with the height of less than one and a half of the cylinder side width the maximum bed shear stress amplification is about 60% of the value of an infinite long cylinder. The quantification of the shear stress reduction is important for scour protection design.

Typically the combustion in engines are open-loop controlled. By using an in-cylinder pressure sensor it is possible to create virtual sensors for closed-loop combustion control (CLCC). With CLCC it is possible to counteract dynamic effects as component ageing, fuel type and cylinder variance. A virtual sensor system was implemented based on a one-zone heat-release analysis, including signal processing of the pressure sensor input. A parametrisation of the heat-release based on several Vibe functions was implemented with good results. The major focus of the virtual sensor system was to perform a tolerance analysis on experimental data, where typical error sources in a production heavy-duty vehicle were identified and their effect on the estimates quantified. It could be concluded that estimates are very much dependent on the choice of heat-release and specific heat ratio models. Especially crank angle phasing has a large impact on estimation performance, stressing the importance of accounting for crankshaft torsion in production vehicles. Biodiesel advances the combustion angle and give a lower IMEP and total heat amount compared to standard diesel. However, error sensitivity is not affected. Further investigations must be made on improving the signal processing in terms of gain error compensation and filtering. Also a better understanding of how errors propagate between subsystems in a CLCC system is required for successful implementation.

With tighter emission regulations for road vehicles pushing the technology forward, fuel savings are indirectly affecting the designs and technical solutions of loader cranes. By decentralizing the hydraulic power through driving each actuator separately, the goal of a more efficient crane drive is strived for. This thesis analyzes if the simple concept of a pump-controlled cylinder directly driven by an induction motor is achievable for a loader crane. Further, the crucial role of the induction motor is studied both mathematically and physically. A special research is also performed on energy efficiency and the capability of electric energy regeneration. By forming the transfer function of the system and performing measurements on a physical setup, the conclusion is drawn that the proposed pump-controlled cylinder concept is fully functional for its purpose which implies that the technology is promising. The report identifies a number of complications with this configuration, such as the induction motor demonstrating reduced performance at high loads and low speeds. Suggestions of improvements are presented with regards to these issues. The thesis also demonstrates high efficiency during a lifting motion and that the possibility of efficient electric energy regeneration is achievable if an optimum lowering speed is considered.

Made available in DSpace on 2014-06-11T19:27:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-12-12Bitstream added on 2014-06-13T18:31:08Z : No. of bitstreams: 1 feijo_v_me_ilha.pdf: 1118421 bytes, checksum: 45161ec0115e5de73f56c75260fc6806 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Neste trabalho considera-se a interação fluido-estrutura em um modelo numérico tridimensional do escoamento sanguíneo no interior da artéria aorta abdominal humana. O sangue é considerado um fluido incompressível e Newtoniano e é governado pelas equações de Navier- Stokes. As paredes da aorta são modeladas a partir da Lei de Hooke, considerando a condição quase-estática. Uma solução numérica é desenvolvida para calcular os campos de pressão e velocidade do fluido e o campo de deslocamento da artéria. Exemplos experimentais foram utilizados como parâmetros validadores do modelo numérico através do método dos elementos finitos. / In this work we are considered the interaction fluid-structure in a tri-dimensional numeric model of the blood flow inside the artery human abdominal aorta. The blood is considered an incompressible fluid and Newtonian and it is governed by the equations of Navier-Stokes. The walls of the aorta are modeled starting from the Law of Hooke, considering the condition quasi - static. A numeric solution is developed to calculate the pressure fields and speed of the fluid and the field of displacement of the artery. Experimental examples were used as parameters for validates of the model numeric through the method of the finite elements.

Submitted by IGOR RANIÊ SOARES DE ALMEIDA null (igor.almeida@hydrostec.com.br) on 2016-10-06T14:43:05Z No. of bitstreams: 1 ALMEIDA_IRS_ME_GUARA - DISSERTAÇÃO.pdf: 15313376 bytes, checksum: 18d93699ff19c9c948547b05bfbe3cdc (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-10-11T12:50:26Z (GMT) No. of bitstreams: 1 almeida_irs_me_guara.pdf: 15313376 bytes, checksum: 18d93699ff19c9c948547b05bfbe3cdc (MD5) / Made available in DSpace on 2016-10-11T12:50:26Z (GMT). No. of bitstreams: 1 almeida_irs_me_guara.pdf: 15313376 bytes, checksum: 18d93699ff19c9c948547b05bfbe3cdc (MD5) Previous issue date: 2016-08-08 / O MCI (Motor de Combustão Interna) é um produto largamente utilizado na indústria, o que o torna um objeto interessante de estudo, o qual requer constante desenvolvimento com implementação de novas tecnologias. Buscando contribuir para o avanço tecnológico na área, foi realizado um estudo do comportamento estrutural de uma de suas principais peças o bloco de cilindros. O mesmo é responsável pela união de todos os outros elementos, devendo ser suficientemente rígido para absorver os esforços oriundos da explosão no interior da câmara e resultantes das forças de oscilação de primeira e segunda ordem originárias das massas dos elementos oscilatórios do motor. Nesta dissertação desejando definir o carregamento principal sobre o bloco do motor, foram realizados diversos estudos, dentre eles: a regulagem da carga onde analisa-se analiticamente as transferências de gases que circulam em um motor, também foi realizada uma análise estequiométrica do combustível, determinando a sua composição e seu poder calorífico, na sequência foram determinados os parâmetros que caracterizam um motor, definidos aqui como cálculos de desempenho, estes foram inter-relacionados em uma planilha de Excel. Posteriormente o carregamento principal do bloco foi definido, realizando estudos de casos, com influência sobre a pressão de trabalho dos cilindros, dividindo-os em fatores de carga. A modelagem do bloco foi realizada no software Autodesk Inventor 2012, as dimensões e posicionamentos das partes foram definidas segundo a realização de cálculos e dimensões de projeto como: cálculos de tração nas roscas do cabeçote e dos mancais do motor; medidas de diâmetro e curso dos pistões; cálculos da velocidade média dos pistões, distâncias das engrenagens de distribuição e relações de cálculo como o raio da manivela sobre o comprimento da biela. Como resultado da modelagem obteve-se um sólido 3D o qual foi analisado no software Ansys Work Bench versão V12, definido o carregamento total sobre o bloco, ao final obteve-se uma análise gráfica dos deslocamentos totais, das tensões equivalentes, cortantes, normais e uma análise de fadiga do bloco do motor e sua capa do mancal, obtendo uma resposta estrutural direta para os cálculos analíticos de desempenho e os estudos de caso. / The ICM (Internal Combustion Engine) is a product widely used in the industry, which makes it an interesting object of study, which requires constant development with implementation of new technologies. Seeking to contribute to the technological advancement in the area, was accomplished a study of the structural behavior of one of its main parts the engine block. It is responsible for the union of all the other elements and must be sufficiently rigid to absorb the efforts originated of the blast within the cylinders and resultants of oscillation forces of first and second order originating from the masses of the oscillation elements from the engine. In this dissertation wishing define the main load on the engine block, were performed several studies, among them: the charge of regulation where it is analyzed analytically the transfers of the gases circulating in an engine, it also performed a stoichiometric fuel analysis, determining the composition and calculating its calorific power, in the sequence was determined several parameters that characterize an engine defined as performance calculations, they were interrelated in an Excel spreadsheet. Posteriorly the main load block was defined, realizing case studies, within influence on the work pressure of the cylinders, dividing them into load factors. The modeling of the block was performed in the Autodesk Inventor 2012 software, the dimensions and positions of the parties of the 3D block model were defined according the according performance calculations and according to project dimensions such as for example: traction calculations in the head screws and engine bearings; measurements of diameter and stroke of the pistons; distances of timing gears and calculation relations as crank radius over the length of the rod. As a result there was obtained an 3D model, which was analyzed in Ansys Workbench V12 software, defined the main loading on the block, at the end was obtained a graphical analysis: of total displacements; of the equivalent stresses; shear stress; normal stress and an fatigue analysis of the engine block and engine bearings cape, getting a direct structural response to the analytical calculations of the performance and of the cases studies.