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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Simultaneous multi-design point approach to gas turbine on-design cycle analysis for aircraft engines

Schutte, Jeffrey Scott 06 April 2009 (has links)
Gas turbine engines for aircraft applications are required to meet multiple performance and sizing requirements, subject to constraints established by the best available technology level. The performance requirements and limiting values of constraints that are considered by the cycle analyst conducting an engine cycle design occur at multiple operating conditions. The traditional approach to cycle analysis chooses a single design point with which to perform the on-design analysis. Additional requirements and constraints not transpiring at the design point must be evaluated in off-design analysis and therefore do not influence the cycle design. Such an approach makes it difficult to design the cycle to meet more than a few requirements and limits the number of different aerothermodynamic cycle designs that can reasonably be evaluated. Engine manufacturers have developed computational methods to create aerothermodynamic cycles that meet multiple requirements, but such methods are closely held secrets of their design process. This thesis presents a transparent and publicly available on-design cycle analysis method for gas turbine engines which generates aerothermodynamic cycles that simultaneously meet performance requirements and constraints at numerous design points. Such a method provides the cycle analyst the means to control all aspects of the aerothermodynamic cycle and provides the ability to parametrically create candidate engine cycles in greater numbers to comprehensively populate the cycle design space from which a "best" engine can be selected. This thesis develops the multi-design point on-design cycle analysis method labeled simultaneous MDP. The method is divided into three different phases resulting in an 11 step process to generate a cycle design space for a particular application. Through implementation of simultaneous MDP, a comprehensive cycle design space can be created quickly for the most complex of cycle design problems. Furthermore, the process documents the creation of each candidate engine providing transparency as to how each engine cycle was designed to meet all of the requirements. The simultaneous MDP method is demonstrated in this thesis on a high bypass ratio, separate flow turbofan with up to 25 requirements and constraints and 9 design points derived from a notional 300 passenger aircraft.
2

Автоматизация расчета шума от внутренних источников в информационной модели здания : магистерская диссертация / Automating the calculation of noise from external sources in the building information model

Дикая, В. И., Dikaia, V. I. January 2023 (has links)
В современном мире строительная отрасль активно развивается, и человечество заботит не только вопросы прочности, устойчивости и сохранения тепла, а также вопросы комфорта человека внутри здания. Одним из показателей комфорта является уровень шума. В то же время проектные организации стремятся автоматизировать и ускорить процесс проектирования с сохранением качества выдаваемой документации. Поэтому информационные технологии набирают популярность, являясь одним из ключевых инструментов автоматизации в строительной сфере. В данной работе проанализированы программы автоматизации расчета шума, существующие на рынке сегодня, а также составлено техническое задание для нового расчетного модуля, произведено тестирование итогового программного комплекса. На практике было установлено, что программный комплекс «FORMIT» имеет высокую точность относительно ручного вида расчета. В то же время значительно сокращает время выполнения работы проектировщика. / In the modern world, the construction industry is actively developing, and humanity is concerned not only with the issues of strength, stability and heat preservation, but also with the comfort of a person inside the building. One measure of comfort is the noise level. At the same time, design organizations strive to automate and speed up the design process while maintaining the quality of the documentation issued. Therefore, information technology is gaining popularity, being one of the key automation tools in the construction industry. In this paper, the noise calculation automation programs that exist on the market today are analyzed, and the terms of reference for a new calculation module are drawn up, and the final software package is tested. In practice, it was found that «FORMIT» software package has high accuracy relative to the manual type of calculation. At the same time, it significantly reduces the time of the designer's work.
3

Автоматизация расчета шума от внешних источников в информационной модели здания : магистерская диссертация / Automating the calculation of noise from external sources in the building information model

Синченкина, М. И., Sinchenkina, M. I. January 2023 (has links)
В современном мире строительная отрасль активно развивается, и человечество заботит не только вопросы прочности, устойчивости и сохранения тепла, а также вопросы комфорта человека внутри здания. Одним из показателей комфорта является уровень шума. В то же время проектные организации стремятся автоматизировать и ускорить процесс проектирования с сохранением качества выдаваемой документации. Поэтому информационные технологии набирают популярность, являясь одним из ключевых инструментов автоматизации в строительной сфере. В данной работе проанализированы программы автоматизации расчета шума, существующие на рынке сегодня, а также составлено техническое задание для нового расчетного модуля, произведено тестирование итогового программного комплекса. На практике было установлено, что программный комплекс «FORMIT» имеет высокую точность относительно ручного вида расчета. В то же время значительно сокращает время выполнения работы проектировщика. / In the modern world, the construction industry is actively developing, and humanity is concerned not only with the issues of strength, stability and heat preservation, but also with the comfort of a person inside the building. One measure of comfort is the noise level. At the same time, design organizations strive to automate and speed up the design process while maintaining the quality of the documentation issued. Therefore, information technology is gaining popularity, being one of the key automation tools in the construction industry. In this paper, the noise calculation automation programs that exist on the market today are analyzed, and the terms of reference for a new calculation module are drawn up, and the final software package is tested. In practice, it was found that «FORMIT» software package has high accuracy relative to the manual type of calculation. At the same time, it significantly reduces the time of the designer's work.
4

Emission Reduction During Ship Maneuvering Motions Through Optimum Propeller Selection / Emissionsminskning Under Skeppsmanövreringsrörelser Genom Optimalt Val av Propeller

Ziaei Dehbarez, Ali January 2024 (has links)
In 2018, the shipping industry accounted for 2.89% of worldwide greenhouse gas (GHG) emissions, with carbon dioxide (CO2) being the most significant GHG affecting global warming (IMO, 2020). This research aims to introduce a method for selecting propellers at the early design stage to lower CO2 emissions from ships.Traditionally, propeller design assumes that a ship travels in a straight line at a constant speed. However, real-sea conditions involve environmental forces and ship maneuvering, requiring frequent adjustments in speed and direction. These adjustments affect the flow angle and velocity at the propeller, causing it to operate outside its design point and, as a result, reducing its efficiency.To tackle this issue, a MATLAB-based simulation program was developed. Which predicts ship maneuvering motions in 4 degrees of freedom (DOF)—surge, sway, yaw, and roll—using the MMG model. The program applies wave and wind forces, calculates ship motion responses in each iteration, and employs two controllers to manage the rudder and propeller speed, ensuring the ship stays on course and arrives on time.The optimization process is iterative, using simulation outcomes to determine propeller speed, thrust, drift angle, etc., and then selecting an optimized propeller with the program's optimization tool that is more adequate for the operational condition.Building on Trodden's (2014) work, this approach improves maneuvering simulations' accuracy by incorporating ship rolling motion, more realistic wave modeling, and more accurate hydrodynamic coefficients. This offers a closer representation of operational conditions.Case studies comparing this method with the traditional approach to propeller selection have shown the simulation program's precision and its effectiveness in improving propeller open water efficiency by 1.65% and reducing CO2 emissions by 1.47% for a Pure Car Carrier (PCC) ship. The results of the research showed a promising potential for the program to predict ship maneuvering motions in real-sea conditions and optimize the propeller. / År 2018 stod sjöfartsindustrin för 2,89 % av de globala utsläppen av växthusgaser (GHG), där koldioxid (CO2) är den mest betydande växthusgasen som påverkar den globala uppvärmningen (IMO, 2020). Denna forskning syftar till att introducera en metod för val av propellrar i det tidiga designskedet för att sänka CO2-utsläppen från fartyg.Traditionellt antar propellerdesignen att ett fartyg reser i rakt linje med konstant hastighet. Men verkliga sjöförhållanden involverar miljöpåverkan och fartygsmanövreringar, vilket kräver frekventa justeringar av hastighet och riktning. Dessa justeringar påverkar flödesvinkeln och hastigheten vid propellern, vilket gör att den opererar utanför sin designpunkt och som ett resultat minskar dess effektivitet. För att ta itu med denna fråga utvecklades ett MATLAB-baserat simuleringsprogram. Programmet förutsäger fartygsmanövreringsrörelser i 4 frihetsgrader (DOF) - surge, sway, yaw och roll - med användning av MMG-modellen. Programmet tillämpar våg- och vindkrafter, beräknar fartygsrörelsesvar i varje iteration och använder två kontrollanter för att hantera rodret och propellerhastigheten, vilket säkerställer att fartyget håller kursen och ankommer i tid.Optimeringsprocessen är iterativ, använder simuleringsresultat för att bestämma propellerhastighet, dragkraft, drifvinkel osv., och väljer sedan en optimerad propeller med programmets optimeringsverktyg som är mer lämplig för driftsförhållandet. Genom att bygga vidare på Troddens (2014) arbete förbättrar denna metod noggrannheten i manövreringssimuleringar genom att inkludera fartygets rullningsrörelse, mer realistisk vågmodellering och mer exakta hydrodynamiska koefficienter. Detta erbjuder en närmare representation av driftsförhållanden.Fallstudier som jämför denna metod med det traditionella tillvägagångssättet för val av propeller har visat simuleringsprogrammets precision och dess effektivitet i att förbättra propellerns öppenvatteneffektivitet med 1,65 % och minska CO2-utsläppen med 1,47 % för ett Pure Car Carrier (PCC) -fartyg. Forskningens resultat visade en lovande potential för programmet att förutsäga fartygsmanövreringsrörelser under verkliga sjöförhållanden och optimera propellern.
5

Limit and shakedown analysis of plates and shells including uncertainties

Trần, Thanh Ngọc 15 April 2008 (has links) (PDF)
The reliability analysis of plates and shells with respect to plastic collapse or to inadaptation is formulated on the basis of limit and shakedown theorems. The loading, the material strength and the shell thickness are considered as random variables. Based on a direct definition of the limit state function, the nonlinear problems may be efficiently solved by using the First and Second Order Reliability Methods (FORM/SORM). The sensitivity analyses in FORM/SORM can be based on the sensitivities of the deterministic shakedown problem. The problem of reliability of structural systems is also handled by the application of a special barrier technique which permits to find all the design points corresponding to all the failure modes. The direct plasticity approach reduces considerably the necessary knowledge of uncertain input data, computing costs and the numerical error. / Die Zuverlässigkeitsanalyse von Platten und Schalen in Bezug auf plastischen Kollaps oder Nicht-Anpassung wird mit den Traglast- und Einspielsätzen formuliert. Die Lasten, die Werkstofffestigkeit und die Schalendicke werden als Zufallsvariablen betrachtet. Auf der Grundlage einer direkten Definition der Grenzzustandsfunktion kann die Berechnung der Versagenswahrscheinlichkeit effektiv mit den Zuverlässigkeitsmethoden erster und zweiter Ordnung (FROM/SORM) gelöst werden. Die Sensitivitätsanalysen in FORM/SORM lassen sich auf der Basis der Sensitivitäten des deterministischen Einspielproblems berechnen. Die Schwierigkeiten bei der Ermittlung der Zuverlässigkeit von strukturellen Systemen werden durch Anwendung einer speziellen Barrieremethode behoben, die es erlaubt, alle Auslegungspunkte zu allen Versagensmoden zu finden. Die Anwendung direkter Plastizitätsmethoden führt zu einer beträchtlichen Verringerung der notwendigen Kenntnis der unsicheren Eingangsdaten, des Berechnungsaufwandes und der numerischen Fehler.
6

Robust design methodology for common core gas turbine engines

Sands, Jonathan Stephen 08 June 2015 (has links)
A gas turbine engine design process was developed for the design of a common core engine family. The process considers initial and projected variant engine applications, likely technology maturation, and various sources of uncertainty when making initial core design considerations. A physics based modeling and simulation environment was developed to enforce geometric core commonality between the core defining design engine and a common core variant engine. The environment also allows for upgrade options and technology to be infused into the variant engine design. The relationships established in the model enable commonality to be implicitly enforced when performing simultaneous design space explorations of the common core design and all corresponding variant engine designs. A robust design simulation process was also developed, enabling probabilistic surrogate model representations of the common core engine family design space to be produced. The probabilistic models provide confidence interval performance estimates with a single function call for an inputted set of core and variant design settings and the uncertainty distribution shape parameter settings representative of an uncertainty scenario of interest. The unique form of the probabilistic surrogate models enables large numbers of common core engine family applications to be considered simultaneously, each being simulated under a unique uncertainty scenario. Implications of core design options can be instantaneously predicted for all engine applications considered, allowing for favorable common core design regions to be identified in a highly efficient manner.
7

Автоматизация акустического расчета вентиляционных систем в задачах проектирования для компании Стройтекпроект : магистерская диссертация / Automation of acoustic calculation of ventilation systems in design tasks for the Stroytechproekt company

Пестов, М. А., Pestov, M. A. January 2023 (has links)
Разработан плагин для акустического расчета вентиляционных систем, используемый для выполнения задач компании Стройтекпроект. Способность плагина определять октавный спектр вентиляционного шума в расчетных точках, уровень звукового давления на пути распространения шума по системе вентиляции, рассчитывать снижение уровня звукового давления на разных участках. / A plug-in for acoustic calculation of ventilation systems has been developed, which is used to perform the tasks of the Stroytekproekt company. The ability of the plug-in to determine the octave spectrum of ventilation noise at the calculated points, the sound pressure level on the path of noise propagation through the ventilation system, to calculate the decrease in the sound pressure level at different sites.
8

Limit and shakedown analysis of plates and shells including uncertainties

Trần, Thanh Ngọc 12 March 2008 (has links)
The reliability analysis of plates and shells with respect to plastic collapse or to inadaptation is formulated on the basis of limit and shakedown theorems. The loading, the material strength and the shell thickness are considered as random variables. Based on a direct definition of the limit state function, the nonlinear problems may be efficiently solved by using the First and Second Order Reliability Methods (FORM/SORM). The sensitivity analyses in FORM/SORM can be based on the sensitivities of the deterministic shakedown problem. The problem of reliability of structural systems is also handled by the application of a special barrier technique which permits to find all the design points corresponding to all the failure modes. The direct plasticity approach reduces considerably the necessary knowledge of uncertain input data, computing costs and the numerical error. / Die Zuverlässigkeitsanalyse von Platten und Schalen in Bezug auf plastischen Kollaps oder Nicht-Anpassung wird mit den Traglast- und Einspielsätzen formuliert. Die Lasten, die Werkstofffestigkeit und die Schalendicke werden als Zufallsvariablen betrachtet. Auf der Grundlage einer direkten Definition der Grenzzustandsfunktion kann die Berechnung der Versagenswahrscheinlichkeit effektiv mit den Zuverlässigkeitsmethoden erster und zweiter Ordnung (FROM/SORM) gelöst werden. Die Sensitivitätsanalysen in FORM/SORM lassen sich auf der Basis der Sensitivitäten des deterministischen Einspielproblems berechnen. Die Schwierigkeiten bei der Ermittlung der Zuverlässigkeit von strukturellen Systemen werden durch Anwendung einer speziellen Barrieremethode behoben, die es erlaubt, alle Auslegungspunkte zu allen Versagensmoden zu finden. Die Anwendung direkter Plastizitätsmethoden führt zu einer beträchtlichen Verringerung der notwendigen Kenntnis der unsicheren Eingangsdaten, des Berechnungsaufwandes und der numerischen Fehler.

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