Approved for public release, distribution unlimited / Steam leakage from an aircraft carrier catapult is sometimes ingested into the aircraft engines upon launch which may induce compressor stall. Investigation of this phenomenon is of particular interest to the Navy with its new F35C, the aircraft carrier variant of the joint strike fighter. The single engine configuration of the F-35C makes this aircraft particularly vunerable to steam-induced stall. The present study examined both throttle-induced stall and steam-induced stall in a compressor at 90% and 95% speed through the use of 9 Kulite and 2 hot-film pressure transducers. The use of Fast Fourier Transform waterfall plots of the transient data before and during stall proved invaluable in determining stall precursors as well as the mode of rotor stall. In addition, a new computational fluid dynamic model was designed using CFX-5 software to represent a single blade passage of the compressor rotor, in order to predict compressor performance. The computed results were compared to experimental results gathered at various throttle settings. An accurate model will enable researchers to predict compressor performance for various and multiple gases. / Outstanding Thesis

Diante do expressivo aumento do número de refinarias de petróleo, bem como, com a crescente modernização das tecnologias de processo, englobando também o ramo petroquímico e de fertilizantes, notou-se que o consumo de energia de compressores centrífugos e suas eficiências tornaram-se de suma importância. Uma consequência desta nova realidade, está na necessidade de melhoria dos métodos estimativos para pré-dimensionamento e performance destas máquinas, o que necessariamente implica em uma previsão precisa de sua eficiência politrópica. Além disso, tais métodos devem também estimar as dimensões básicas de cada seção de compressão. A maior parte da literatura atual, versando sobre compressores centrífugos, tipo multiestágio, não está atualizada no que diz respeito à estimativa de eficiências politrópicas, quando comparadas com as eficiências alcançadas por compressores de fornecimento recente. Sendo assim, o principal objetivo da presente dissertação foi estimar um compressor centrífugo multiestágio, utilizando métodos adequados de cálculo. Isto implicou em comparar três métodos de estimativas, refletindo três procedimentos clássicos de cálculo, normalmente utilizados. Após pesquisa foram identificados três métodos, dois otimizados recentemente e um terceiro de abordagem mais antiga, proveniente de alguns fornecedores de compressores. Os métodos em análise são: Método das relações de Semelhança Otimizado por Sandberg (2016), Método de Lüdtke (2004), com correções propostas por Busaid e Pilidis (2016) e finalmente o Método dos Expoentes Politrópicos (N-Method), apresentado por Gresh (2001) e editado novamente em Gresh (2018). Os dois métodos mais recentes, embora baseados em diferentes critérios, apresentam estimativas de desempenho, dentro de uma precisão razoável, quando comparada aos dados reais de teste, enquanto que o método mais antigo, apresenta desvios significativos. Nesta dissertação, serão estimados seis casos reais de compressores, cujos resultados serão comparados aos estimados pelos três métodos de cálculo. Analisando os métodos, à luz dos desvios indicados nas tabelas para os seis casos, pode-se afirmar que o Método Simplificado e Corrigido de Lüdtke foi o que apresentou melhores resultados. O desvio relativo máximo apresentado foi na potência de eixo, cujo valor foi de 5,1%. Considerando o Método de Sandberg, verifica-se a partir dos desvios listados nas tabelas, que não cumpriu com o limite de aceitabilidade no tocante à potência no eixo para dois dos casos estudados. Entretanto, com exceção a estes dois casos, o método mostrou-se bastante satisfatório. Finalmente, analisando o Método dos Expoentes Politrópicos, citado por Gresh (2018), pode-se dizer que este método só foi aceitável para dois casos. Para os demais, segundo os desvios indicados nas tabelas, o método mostrou-se inadequado devido a desvios significativos na sua eficiência politrópica. / With the crescent number of modern fertilizer plants and hydrocracking process units in oil refineries, the consumption of energy and consequently the efficiency of centrifugal compressors were made of paramount importance in present day. A consequence of this new reality is the necessity of improvement of the methods that estimate the polytropic efficiency of these compressors. Furthermore, new methods also need to predict the basic geometric parameters of each machine. On the other side, most of the literature, which deals with polytropic efficiencies, is not up to date with the values performed by modern compressors. The main scope of present work is to provide background information and present a comparison between two up to date methods and a third classical old method, based on different approach, but capable to predict the performance and sizing of multistage centrifugal compressors. The methods under analysis are: Sandberg (2016) Optimized Similarity Method, Lüdtke\'s Method (2004), with corrections proposed by Busaid and Pilidis (2016) and finally the Politropic Exponent Method (N-Method), presented by Gresh (2001) and edited again in Gresh (2018). Both the newer methods present good agreement with the values performed by several compressors, as demonstrated when these methods are adopted, whilst the old method presents some deviations, mainly in the gas power. In this paper, six real cases will be estimated by the three methods and compared against supplier data; the results will be justified. Analyzing the methods, in respect of the deviations indicated in the tables for the six cases, it can be stated that the Simplified and Corrected Method of Lüdtke was the one that presented the best results. The maximum relative deviation presented was in the brake horsepower, whose value was of 5.1%. Considering the Sandberg Method, it can be verified from the deviations listed in the tables, that it did not meet the limit of acceptability regarding power on the axis for two of the cases studied. However, with the exception of these two cases, the method was quite satisfactory. Finally, analyzing the Politropic Exponents Method, quoted by Gresh (2018), it can be said that this method was only acceptable for two cases. For the others, according to the deviations indicated in the tables, the method proved to be inadequate, due to significant deviations in its polytropic efficiency.

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Michael S. Idelchik. / M.S.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND AERO / Includes bibliographical references. / by Saeed Farokhi. / Ph.D.

No description available.

Demand Side Management (DSM) is one of the most viable and sustainable short term methods to address the shortfall in electricity generation in South Africa. This is because DSM projects can be implemented relatively quickly and inexpensively when compared with alternative generation options. This specifically applies to the mining industry. South African mines presently consume 15% of Eskom-generated electricity. Mine compressed air systems are some of the biggest users, consuming approximately 21% of mine electricity consumption. Electricity savings on compressed air systems are therefore important. With this study, various Energy Efficiency methods on compressed air systems were investigated. These methods include variable speed drives on compressor motors, temperature control of compressor discharge, minimising pressure drops in the air distribution systems, eliminating compressed air leaks, and optimising compressor selection and control. The most efficient strategies were identified, taking into account factors such as financial viability, sustainability, and ease of implementation. The best strategies were found to be the optimised control and selection of compressors, minimising compressed air leaks, and the optimal control of system pressure. These strategies were implemented and tested on large compressed air systems in gold and platinum mines. Savings of between 10% and 35% on the maximum demand of the systems were achieved. In present monetary terms this translates to as much as R108 million savings for the mines per year at the end of 2009 tariffs. If total mine compressed air electricity consumption can reduce by 30%, it will result in nearly a 1% reduction in total Eskom demand. This shows that mine compressed air savings can make a significant contribution to the drive for Energy Efficiency in South Africa. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.

Demand Side Management (DSM) is one of the most viable and sustainable short term methods to address the shortfall in electricity generation in South Africa. This is because DSM projects can be implemented relatively quickly and inexpensively when compared with alternative generation options. This specifically applies to the mining industry. South African mines presently consume 15% of Eskom-generated electricity. Mine compressed air systems are some of the biggest users, consuming approximately 21% of mine electricity consumption. Electricity savings on compressed air systems are therefore important. With this study, various Energy Efficiency methods on compressed air systems were investigated. These methods include variable speed drives on compressor motors, temperature control of compressor discharge, minimising pressure drops in the air distribution systems, eliminating compressed air leaks, and optimising compressor selection and control. The most efficient strategies were identified, taking into account factors such as financial viability, sustainability, and ease of implementation. The best strategies were found to be the optimised control and selection of compressors, minimising compressed air leaks, and the optimal control of system pressure. These strategies were implemented and tested on large compressed air systems in gold and platinum mines. Savings of between 10% and 35% on the maximum demand of the systems were achieved. In present monetary terms this translates to as much as R108 million savings for the mines per year at the end of 2009 tariffs. If total mine compressed air electricity consumption can reduce by 30%, it will result in nearly a 1% reduction in total Eskom demand. This shows that mine compressed air savings can make a significant contribution to the drive for Energy Efficiency in South Africa. / Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.

A modular structural design methodology for composite blades is developed. This design method can be used to design composite rotor blades with sophisticate geometric cross-sections. This design method hierarchically decomposed the highly-coupled interdisciplinary rotor analysis into global and local levels. In the global level, aeroelastic response analysis and rotor trim are conduced based on multi-body dynamic models. In the local level, variational asymptotic beam sectional analysis methods are used for the equivalent one-dimensional beam properties. Compared with traditional design methodology, the proposed method is more efficient and accurate. Then, the proposed method is used to study three different design problems that have not been investigated before. The first is to add manufacturing constraints into design optimization. The introduction of manufacturing constraints complicates the optimization process. However, the design with manufacturing constraints benefits the manufacturing process and reduces the risk of violating major performance constraints. Next, a new design procedure for structural design against fatigue failure is proposed. This procedure combines the fatigue analysis with the optimization process. The durability or fatigue analysis employs a strength-based model. The design is subject to stiffness, frequency, and durability constraints. Finally, the manufacturing uncertainty impacts on rotor blade aeroelastic behavior are investigated, and a probabilistic design method is proposed to control the impacts of uncertainty on blade structural performance. The uncertainty factors include dimensions, shapes, material properties, and service loads.

Thesis (M.App.Sc.) - Carleton University, 2005. / Includes bibliographical references (p. 174-179). Also available in electronic format on the Internet.

Thesis (Ph.D.)--Mississippi State University. Department of Aerospace Engineering. / Title from title screen. Includes bibliographical references.