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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.
101

Propulsion Unit of a 3DOF Helicopter

Ling, Gustav, Persson, Jesper January 2015 (has links)
This Bachelor thesis is a part of a bachelor project which includes building, programming and controlling a 3DOF tandem helicopter. This particular report deals with the propulsion units, i.e. the motors and propellers of the helicopter. It covers the process of how to determine the most suitable propulsion units for the rig that eventually will enable it to run. To achieve this, different data have been processed. Torque and thrust are two important parameters that have been studied. The data have been acquired by different tests, e.g. thrust measurements from a thrust rig. Also more complex analysis such as Blade Element Theory and Actuator Disk Theory have been carried out in order to determine the behaviour of the propulsion units. Study data sheets and databases was also a part of the work. The result of this work was two equal propulsion units which were mounted in the helicopter. They proved to work satisfactory and provided wanted dynamics to the system. / Design & Implementation of a 3DOF Helicopter
102

Modélisation hors adaptation des performances individuelles d'un doublet d'hélices contrarotatives / Individual performance modelization of contra rotating propellers in off-design conditions

Dubosc, Matthieu 02 February 2016 (has links)
Dans le cadre du projet européen Clean Sky, Snecma construit un démonstrateur de Contra Rotating Open Rotor (CROR). La conception du système de régulation du moteur nécessite d'avoir connaissance du comportement aérodynamique de chacune des hélices du doublet. Les objectifs de cette thèse sont dans un premier temps de comprendre les interactions entre les différents éléments constitutifs d'un CROR ayant un effet sur les performances des hélices, d'isoler leurs contributions respectives et dans un deuxième temps de développer un modèle prédictif des performances individuelles des hélices d'un CROR intégrable dans un environnement de calcul de cycles thermodynamiques. Pour cela, le comportement des hélices en doublet est rapproché de celui d'hélices isolées dont les effets macroscopiques sont bien connus. Des calculs Euler et NS3D ont servi de base pour proposer un couplage entre les hélices isolées permettant de retrouver le champ de vitesses induits entre les hélices d'un calcul doublet. Pour respecter les exigences de rapidité d'exécution et de robustesse numérique imposées par l’environnement de calcul de cycles thermodynamiques, les performances individuelles des hélices du doublet sont calculées à partir de champs hélice isolée. Une approche monodimensionnelle permet de calculer les vitesses induites propres des hélices à partir de la traction et de la puissance absorbée et une méthode pour estimer les vitesses induites mutuelles à partir des vitesses induites propres est donnée. Le calcul des performances individuelles des hélices d'un doublet contrarotatif est itératif. Cette méthode estime les performances avec une erreur relative inférieure à 5%. Elle est utilisée dans le développement du système de régulation du démonstrateur CROR SAGE2. / Within the scope of the European research project Clean Sky, Snecma builds a ground demonstrator of the concept engine Contra Rotating Open Rotor (CROR). Engine control system design requires knowing how each propeller will behave aerodynamically under the interaction of each other. The aim of this work is to design a predictive model of contra rotating propeller individual performance fitting in a thermodynamic cycle calculation environment. A coupling is proposed in order to represent the dual propellers thanks to isolated propeller behavior. It has been shown that by matching the isolated propellers thrust and torque to the doublet values, the good values of mutual induced velocities can be found. Hence contra rotating propellers individual performance can be reached with a good variation in parameters. In addition to that, in order to meet withthermodynamic cycle calculation environment requirements of rapidity and numerical robustness, performance is calculated from pre-generated propeller maps. One-dimensional approach is used to calculate mutual induced velocities from propellers thrust and torque. Contra rotating propellers individual performance calculation is an iterative process. The method developed gives the performance within a 5% relative error margin and is currently used for the design of the ground demonstrator control system.
103

Univerzální charakteristiky pístových motorů s vrtulí / Universal characteristics of piston engines with a propeller

Šafránek, Martin January 2021 (has links)
Determining the characteristics of piston engines with a propeller is a complex task. Accurate calculations are based on engine and propeller characteristics from the manufacturers, which are, however, quite demanding. It is also possible to use simplified models that can predict the achievable values of propeller efficiency and fuel consumption. They are based on a simple propeller efficiency and maximum power. However, these models are often very inaccurate, which is a significant disadvantage. Therefore, it is possible to use the universal characteristics of propeller propulsion units, which offers a more accurate calculation of power and fuel consumption using a relatively simple model. The diploma thesis deals with a summary description of all characteristics of reciprocating internal combustion engines and propellers. A mathematical model was created here, which works according to a certain algorithm based on the joint work of the engine and the propeller. This model can predict the required power and fuel consumption in different flight modes much more accurately. The results were applied to the performance of ultralight aircraft, especially to the range, which was significantly increased.
104

Návrh letounu pro vlekání a základní akrobacii / Design of a aircraft for towing and basic acrobtics

Loutocký, Jiří January 2010 (has links)
This master thesis solves conceptual design of aerotow airplane and airplane for basic aerobatics. Airplane is designed by using of specification CS-23. The first part of the thesis solves conceptual design. Especially possible concepts and choice the best one according to requests. Next part deals with flight performance of aerotow airplane in normal flight and also in aerobatics. The third part is engaged in main flight performance in aerotow. 3D system model of whole aircraft and compact disk with mentioned 3D model and electronic version of thesis is also added.
105

STABILIZATION OF QUADCOPTER BY NESTED SATURATION FEEDBACK AND CONTROABILITY ANALYSIS

Zhu, Sizhe 26 August 2022 (has links)
No description available.
106

Measurement of Static and Dynamic Performance Characteristics of Electric Propulsion Systems

Brezina, Aron Jon 21 June 2012 (has links)
No description available.
107

Actuator Modeling and Control For a Three Degrees of Freedom Differential Thrust Control Testbed

Garimella, Suresh January 2007 (has links)
No description available.
108

En jämförelsestudie av fritidsbåtar mellan The Candela Seven och AMT 230 GP / A comparative study of leisure boats between the Candela Seven and AMT 230 GP

Pulat, Arpat, Zaierding, Tayierjiang January 2021 (has links)
Detta examensarbete går ut på att utföra en analys i form av en jämförelsestudie av två fritidsbåtar med funktions, ekonomisk samt hållbarhetsaspekter i fokus. Projektet utgår samt är inriktad på en eldrivenbärplansbåt The Candela Seven från elmotorbåtsproducent Candela Speed Boat AB där båten jämförs med motorbåten AMT 230 GP från Advanced Marine Tech Premium Boats och utvärderas dels med hjälp av Havsmiljöinstitutets samarbete mellan olika institutioner i Sverige som referensram. Projektmålen är att genom analys och utvärderingar av jämförelsearbete utse båten som ska prioriteras mellan Candela Seven och AMT 230 GP samt komma med eventuella rekommendationer ur funktions-, ekonomiska samt hållbarhetsperspektiv. Arbetet startade med en nulägesanalys för att skapa insikt i produktfunktionalitet av båtarna, vilka ekonomisk och hållbarhetsfördelar produkten har samt hur marknaden ser ut för elbåtar med kundbehov i fokus. För vidareanalys av insamlade data och fakta för jämförelsearbete genomfördes SWOT- och kvantitativa analysmetoder samt genom matematiska resonemang och analyser identifiera båtens egenskaper och fördelar jämfört med konkurrenten. I jämförelseanalys används jämförelsematris för värdering och sammanställning av olika parametrar mot varandra samt utse båten som ska prioriteras. I jämförelseanalysen med olika parametrar visades Candela Seven är en gynnsammare båt att välja eller köpa och som prioriteras i jämförelse med AMT 230 GP. Fokus kan bli att hitta flera kunder som är intressanta, eller produktanpassa för att uppfylla kunders önskemål. Nulägesanalys genomfördes som visar att en huvudkonkurrent med bensindriven båt identifierades samt är ett substitut som utmanar produkten. Utmärkta egenskaper från SWOT och Kvantitativa-analysen är att Candela Seven är energisparande samt lönsammare att driva med mindre underhåll jämfört med AMT 230 GP. Dessutom är produkten miljövänligare i körning med hållbarhetstänkande egenskaper och design. / This thesis is based on performing an analysis in the form of a comparative study of two leisure boats with functional, economic and sustainability aspects in focus. The project is based and focuses on an electric hydrofoil boat The Candela Seven from electric motorboat manufacturer Candela Speed Boat AB where the boat is compared with the motorboat AMT 230 GP from Advanced Marine Tech Premium Boats and evaluatedpartly with the help of the Institute of Marine Environment's cooperation betweendifferent institutions in Sweden as a reference framework. The project goals are to, through analysis and evaluations of comparative work,designate the boat that will be prioritized between Candela Seven and AMT 230 GP andgive eventual recommendations from a functional, financial and sustainabilityperspective. The work started with a current situation analysis to create insight into the productfunctionality of the boats, what economic and sustainability benefits the product hasand what the market looks like for electric boats with customer needs in focus. Forfurther analysis of collected data and facts for comparative work, SWOT andquantitative analysis methods were performed and through mathematical reasoning andanalyzes to identify the boat's properties and advantages compared to the competitor. In comparison analysis, a comparison matrix is used for valuation and compilation ofdifferent parameters against each other and to designate the boat to be prioritized.In the comparison analysis with various parameters, Candela Seven was shown to be amore favorable boat to choose or buy and which is prioritized in comparison with theAMT 230 GP. The focus can be on finding more customers that are interesting, orproduct adaptation to fulfill customer needs. The current situation analysis was carried out which shows that a main competitor witha petrol-powered boat was identified and is a substitute that challenges the product.Excellent features from the SWOT and Quantitative analysis are that Candela Seven isenergy-saving and more profitable to operate with less maintenance cost compared to the AMT 230 GP. In addition, the product is more environmentally proficient whendriving with sustainability-thinking properties and design.
109

Elektrisk konvertering av långsamtgående båtar

Olsson, Fredrik, Rosenberg, Simon January 2024 (has links)
Att minska mängden koldioxidutsläpp är ett centraliserat mål för EU, med avsikt att bli koldioxidneutral 2050. Inom sjöfartsnäringen, särskilt fritidsbåtssektionen, kan minskningar av koldioxidutsläppen göras på individnivå genom att välja elektrisk framför fossil framdrivning. Denna rapport undersöker om effektbesparingar kan uppnås vid en marschfart på 8 knop, genom att använda en elmotor framför en förbränningsmotor. Eftersom elmotorer tenderar att ha andra egenskaper än förbränningsmotorer, väcker det också frågan om vilken typ av propeller som kan utnyttja elmotorns egenskaper. För att genomföra denna analys skapas en teoretisk modell i MATLAB Simulink. Båtens skrov 3D-skannas för att extrahera en yt-modell, som sedan har använts med ett CFD-verktyg (Computational Fluid Dynamics) för att uppskatta motstånd (skrovmotstånd) vid en given hastighet. Tillsammans med data från en förbränningsmotors datablad och aktuella propelleregenskaper, utgör denna information grunden för att bygga och utvärdera modellen. Resultaten från denna teoretiska modell har visat sig spegla den insamlade data upp till 95 % av verkligheten, vilket gör modellen acceptabel för påbyggande resultat som vid optimering av propeller. Den teoretiska modellen med förbränningsmotorn visade sig förbruka 7901 W vid 5 knop, där 17.1 % procent av energin från bränslet gick till att driva båten framåt. En elektrifierad version av den teoretiska modellen hade förbrukat 3935 W vid 5 knop, där 34.2 % procent av energin in i motorn gick till att driva båten framåt. Tillsammans med den bästa propellern från optimering av propeller kan framdrivningseffektiviteten öka till 36.17 %. Valet av elektrifiering ger i rapportens fall en ökning av energieffektivitet på 211 % jämfört med teoretisk modell med förbränningsmotor. / Decreasing the amount of carbon dioxide emissions is a centralized goal for theEU, with a target goal of becoming carbon neutral by 2050. Within the maritimeindustry, especially the recreational boating section, reductions of carbondioxide emissions can be made at an individual level by choosing electrical overfossil propulsion.This report investigates whether savings in power can be achieved at cruisingspeed of 8 knots, by using an electric engine over a combustion engine. Sinceelectrical engines tend to have different characteristics than combustion engines,it also raises the question of which type of propeller can utilize thecharacteristics of an electrical engine.To conduct this analysis, a theoretical model in MATLAB Simulink is created.The boat’s hull is 3D-scanned to extract a mesh model, which can then be usedwith computational fluid dynamics (CFD) tools to estimate resistance at a givenspeed. Along with data from combustion engine datasheets and currentpropeller characteristics, this information forms the basis for building andevaluating the model.The results from this theoretical model have shown to mirror the recorded dataup to 95 % of reality, making the model acceptable for further results such aspropeller optimization.The theoretical model with the combustion engine was found to consume 7901Wat 5 knots, where 17.1 % of the energy from the fuel went to propel the boatforward. An electrified version of the theoretical model would have consumed3935W at 5 knots, where 34.2 % of the energy input into the engine went topropelling the boat forward. Together with the best propeller from the propelleroptimization, the propulsion efficiency can increase to 36.17 %. In the report’scase, the choice of electrification results in an increase in energy efficiency of211 % compared to the theoretical model with the combustion engine.
110

Ducted Fan Aerodynamics and Modeling, with Applications of Steady and Synthetic Jet Flow Control

Ohanian, Osgar John 17 May 2011 (has links)
Ducted fan vehicles possess a superior ability to maximize payload capacity while minimizing vehicle size. Their ability to both hover and fly at high speed is a key advantage for information-gathering missions, particularly when close proximity to a target is essential. However, the ducted fan's aerodynamic characteristics pose difficulties for stable vehicle flight and therefore require complex control algorithms. In particular, they exhibit a large nose-up pitching moment during wind gusts and when transitioning from hover to forward flight. Understanding ducted fan aerodynamic behavior and how it can be altered through flow control techniques are the two prime objectives of this work. This dissertation provides a new paradigm for modeling the ducted fan's nonlinear behavior and new methods for changing the duct aerodynamics using active flow control. Steady and piezoelectric synthetic jet blowing are employed in the flow control concepts and are compared. The new aerodynamic model captures the nonlinear characteristics of the force, moment, and power data for a ducted fan, while representing these terms in a set of simple equations. The model attains excellent agreement with current and legacy experimental data using twelve non-dimensional constants. Synthetic jet actuators (SJA) have potential for use in flow control applications in UAVs with limited size, weight, and power budgets. Piezoelectric SJAs for a ducted fan vehicle were developed through two rounds of experimental designs. The final SJA design attained peak jet velocities in the range of 225 ft/sec (69 m/s) for a 0.03â x 0.80â rectangular slot. To reduce the magnitude of the nose-up pitching moment in cross-winds, two flow control concepts were explored: flow separation control at the duct lip, and flow turning at the duct trailing edge using a CoandÄ surface. Both concepts were experimentally proven to be successful. Synthetic jets and steady jets were capable of modifying the ducted fan flow to reduce pitching moment, but some cases required high values of steady blowing to create significant responses. Triggering leading edge separation on the duct lip was one application where synthetic jets showed comparable performance to steady jets operating at a blowing coefficient an order of magnitude higher. / Ph. D.

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