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Thesis (M.S.)--West Virginia University, 1998. / Title from document title page. Document formatted into pages; contains x, 82 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 69-70).

Os desenvolvimentos de novos motores têm resultado no aumento constante dos carregamentos mecânicos e térmicos dos componentes. Além de estarem expostos a condições desfavoráveis ao desgaste, os novos componentes do motor devem garantir desempenho similar, ou muitas vezes superior, aos dos componentes atuais. Para os anéis de pistão, o desempenho é dado pela sua capacidade de vedação e raspagem, que podem ser mensurados em motor pelos resultados de consumo de óleo lubrificante (COL) e fluxo de gases para o cárter (blow-by). Sendo assim, a proposta desse trabalho foi a de avaliar-se a influência do tratamento superficial a laser para endurecimento da pista de desgaste do anel de pistão de segundo canalete, em termos do desempenho de vedação e raspagem. Foram comparados dois protótipos, utilizando como padrão um anel de pistão de produção corrente, comercialmente fornecido a clientes. O efeito do tratamento térmico a laser nos anéis foi avaliado em relação a distorções dimensionais. Após isto, foram realizados testes tribológicos de bancada com o objetivo de conhecer o comportamento do anel depois do tratamento laser. De maneira geral o tratamento superficial por laser na superfície de anéis de pistão mostraram resultados significativos no aspecto aumento de dureza, com alguns deméritos no aspecto dimensional que pode interferir na boa funcionalidade do sistema tribológico anel lubrificante cilindro. / The new engine developments are providing engine mechanical and thermal loads increase on the components. Besides the unfavorable wear conditions, the components should provide similar or improved performance compared with current baselines. For piston rings, the performance is given by the ring capacity of sealing and scrapping. These performances can be measured in a engine by the results of lube oil consumption (LOC) and Blow-by. So, the proposal of this work is to evaluate the influence of laser hardening on the second ring wear and verify the sealing and scrapping performance. It was compared two prototypes, being as parameter the current piston ring supplied to customer. Firstly, it was compared the dimensional of the laser hardening effect. After that, it were tested these prototypes in bench tests in order to know the ring performance after laser hardening. In general terms, the superficial treatment by laser on the piston rings surface have showed significant results in the hardness aspects, with some demerits in the dimensional aspect that can interfere in the good functionality of the tribological system, piston rings lubricant cylinder liner.

abstract: Volcanic eruptions are serious geological hazards; the aftermath of the explosive eruptions produced at high-silica volcanic systems often results in long-term threats to climate, travel, farming, and human life. To construct models for eruption forecasting, the timescales of events leading up to eruption must be accurately quantified. In the field of igneous petrology, the timing of these events (e.g. periods of magma formation, duration of recharge events) and their influence on eruptive timescales are still poorly constrained. In this dissertation, I discuss how the new tools and methods I have developed are helping to improve our understanding of these magmatic events. I have developed a method to calculate more accurate timescales for these events from the diffusive relaxation of chemical zoning in individual mineral crystals (i.e., diffusion chronometry), and I use this technique to compare the times recorded by different minerals from the same Yellowstone lava flow, the Scaup Lake rhyolite. I have also derived a new geothermometer to calculate magma temperature from the compositions of the mineral clinopyroxene and the surrounding liquid. This empirically-derived geothermometer is calibrated for the high FeOtot (Mg# = 56) and low Al2O3 (0.53–0.73 wt%) clinopyroxene found in the Scaup Lake rhyolite and other high-silica igneous systems. A determination of accurate mineral temperatures is crucial to calculate magmatic heat budgets and to use methods such as diffusion chronometry. Together, these tools allow me to paint a more accurate picture of the conditions and tempo of events inside a magma body in the millennia to months leading up to eruption. Additionally, I conducted petrological experiments to determine the composition of hypothetical exoplanet partial mantle melts, which could become these planets’ new crust, and therefore new surface. Understanding the composition of an exoplanet’s crust is the first step to understanding chemical weathering, surface-atmosphere chemical interactions, the volcanic contribution to any atmosphere present, and biological processes, as life depends on these surfaces for nutrients. The data I have produced can be used to predict differences in crust compositions of exoplanets with similar bulk compositions to those explored herein, as well as to calibrate future exoplanet petrologic models. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2020

Aim of this diploma thesis is the modification of naturally aspirated engine for Formula Student competition to turbocharged version. Modification which were made are based on the issue knowledge and calculations. The input data were obtained from 3D scanning and measurements, at the school laboratories. All 3D models were created in Pro / Engineer. Input data for the computional analysis was developed in Lotus Engine Simulation. Computational analysis was performed in ANSYS by finite element method. Calculations had to simulate a piston behavior at the critical situations where the engine is under the maxiumum load.

The CFD simulation of cooling piston compressor Stream, manufactured by Emerson company, is the topic of this diploma thesis. Analysis of moving parts (piston, valves) and refrigerant or physical settings for simulation were based on experimental data provided by Emerson. The goal of the thesis is to test opportunities of Star-CCM+ in simulating the flow inside the compressor. In the end there will be a comparison of experimental data and results from the simulation. The thesis also contains a theoretical background of piston compressors and phenomenon following the operating compressor.

This master’s thesis deals with the piston for modified engine 1.4 TSI from Volkswagen concern. It includes calculation of kinematics and forces reactions of the crank mechanism of the engine for speed 6071 rpm elaborated in the program Mathcad Prime. Further the work includes calculation for reducing the magnitude of lateral force and design of several variants of the piston. For the proposed design variants of the piston are performed FEM analysis of mechanical state of stress and comparisons of contact pressures in the program ANSYS Workbench.

The objectives of this research are the prediction of the thermodynamic behavior of a multi-stage intercooled reciprocating compressor and its progressive loss of performance due to leakage. A theoretical model is developed to simulate the thermodynamics of the compressor system and the lubricating condition and wear of the piston ring pack for a multi-stage intercooled reciprocating compressor. A first law of thermodynamics approach is used to determine the thermodynamic properties of the gas inside the cylinders, the intercoolers and the inlet and discharge manifold. The compressor valves are modeled as single degree-of-freedom, spring-mass=damper systems. The flows through the valves are calculated based on the steady flow equations for equivalent orifices. The lubricating condition of the piston ring pack are determined on the basis of hydrodynamic lubrication theory. The wear of the piston rings is assumed to occur when the hydrodynamic oil film between the piston ring and cylinder bore breaks down. Based on the theoretical model, a computer program is developed. This program is tested on an Ingersoll-Rand Model 242, two stage aircooled reciprocating air compressor. The comparison of the experimental values of the pressure variations in the first cylinder with the value predicted by the computer program shows a reasonable match. The computer program predicts the pressure, temperature and mass flow rates for each cylinder and the intercooler. Also predicted is the wear rate of each piston ring. The progressive loss in the compressor mass discharge, and hence the loss in its performance, is determined by calculating the leakage losses several times, updating the leakage area each time based on the wear rate of the piston rings. The result shows a drop of about 15 percent in the discharge rate of the Model 242 compressor after 8000 hours of running time. / Master of Science

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