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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

Model-based design of hybrid electric marine propulsion system using modified low-order ship hull resistance and propeller thrust models

Liu, Siyang 05 January 2021 (has links)
Transportation is a primary pollution source contributing to 14 percent of global greenhouse gas emissions, and 12 percent of transportation emissions came from maritime activities. Emissions from the ferry industry, which carries roughly 2.1 billion passengers and 250 million vehicles annually, is a major concern for the general public due to their near-shore operations. Compared to the rapidly advancing clean automotive propulsion, fuel efficiency and emissions improvements for marine vessels are more urgent and beneficial due to the significantly higher petroleum fuel consumption and heavy pollutants and the relatively slow adoption of clean propulsion technology by the marine industry. Hybrid electric propulsion, proven to be effective for ground vehicles, presents a promising solution for more efficient clean marine transportation. Due to the diversified hull/propulsor design and operation cycle, the development of a hybrid electric marine propulsion system demands model-based design and control optimization for each unique and small batch production vessel. The integrated design and control optimization further require accurate and computation efficient hull resistance and propulsor thrust calculation methods that can be used to predict needed propulsion power and gauge vessel performance, energy efficiency, and emissions. This research focuses on improving the low-order empirical hull resistance and propulsor thrust models in the longitudinal direction by extracting model parameters from one-pass computational fluid dynamics (CFD) simulation and testing the acquired models in integrated design optimization of the marine propulsion system. The model is implemented in MATLAB/Simulink and ANSYS Aqwa and validated using operation data from BC Ferries’ ship Tachek. The modified low-order model (M-LOM) is then used in the integrated optimizations of propulsion system component sizes and operation control strategies for another BC Ferries’ ship, Skeena Queen. The performance, energy efficiency, and emissions of various propulsion options, including nature gas-mechanical and natural gas-electric benchmarks, and hybrid electric alternatives of series hybrid, parallel hybrid, and battery/pure electric are compared to demonstrate the benefits of the new method in completing these complex tasks and hybrid electric marine propulsion. The research forms the foundation for further studies to achieve more accurate propulsion demand prediction and a more comprehensive lifecycle cost assessment of clean marine propulsion solutions. / Graduate
2

Evaluation of hybrid-electric propulsion systems for unmanned aerial vehicles

Matlock, Jay Michael Todd 14 January 2020 (has links)
The future of aviation technology is transitioning to cleaner, more efficient and higher endurance aircraft solutions. As fully electric propulsion systems still fall short of the operational requirements of modern day aircraft, there is increasing pressure and demand for the aviation industry to explore alternatives to fossil fuel driven propulsion systems. The primary focus of this research is to experimentally evaluate hybrid electric propulsion systems (HEPS) for Unmanned Aerial Vehicles (UAV) which combine multiple power sources to improve performance. HEPS offer several potential benefits over more conventional propulsion systems such as a smaller environmental impact, lower fuel consumption, higher endurance and novel configurations through distributed propulsion. Advanced operating modes are also possible with HEPS, increasing the vehicle’s versatility and redundancy in case of power source failure. The primary objective of the research is to combine all of the components of a small-scale HEPS together in a modular test bench for evaluation. The test bench uses components sized for a small-scale UAV including a 2.34kW two-stroke 35cc engine and a 1.65kW brushless DC motor together with an ESC capable of regenerative braking. Individual components were first tested to characterize performance, and then all components were assembled together in a parallel configuration to observe system-level performance. The parallel HEPS is capable of functioning in the four required operating modes: EM Only, ICE Only, Dash Mode (combined EM and ICE power) as well as Regenerative Mode where the onboard batteries get recharged. Further, the test bench was implemented with a supervisory controller to optimize system performance and run each component in the most efficient region to achieve torque requirements programmed into mission profiles. The logic based controller operates with the ideal operating line (IOL) concept and is implemented with a custom LabView GUI. The system is able to run on electric power or ICE power interchangeably without making any modifications to the transmission as the one-way bearing assembly engages for whichever power source is rotating at the highest speed. The most impressive of these sets of tests is the Dash mode testing where the output torque of the propeller is supplied from both the EM and ICE. Working in tandem, it was proved that the EM was drawing 19.9A of current which corresponds to an estimated 0.57Nm additional torque to the propeller for a degree of hybridization of 49.91%. Finally, the regenerative braking mode was proven to be operational, capable of recharging the battery systems at 13A. All of these operating modes attest to the flexibility and convenience of having a hybrid-electric propulsion system. The results collected from the test bench were validated against the models created in the aircraft simulation framework. This framework was created in MATLAB to simulate the performance of a small UAV and compare the performance by swapping in various propulsion systems. The purpose of the framework is to make direct comparisons of HEPS performance for parallel and series architectures against conventional electric and gasoline configuration UAVs, and explore the trade-offs. Each aircraft variable in the framework was modelled parametrically so that parameter sweeps could be run to observe the impact on the aircraft’s performance. Finally, rather than comparing propulsion systems in steady-state, complex mission profiles were created that simulate real life applications for UAVs. With these experiments, it was possible to observe which propulsion configurations were best suited for each mission type, and provide engineers with information about the trade-offs or advantages of integrating hybrid-electric propulsion into UAV design. In the Pipeline Inspection mission, the exact payload capacities of each aircraft configuration could be observed in the fuel burn versus CL,cruise parameter sweep exercise. It was observed that the parallel HEPS configuration has an average of 3.52kg lower payload capacity for the 35kg aircraft (17.6%), but has a fuel consumption reduction of up to 26.1% compared to the gasoline aircraft configuration. In the LIDAR Data collection mission, the electric configuration could be suitable for collection ranges below 100km but suffers low LIDAR collection times. However, at 100km LIDAR collection range, the series HEPS has an endurance of 16hr and the parallel configuration has an endurance of 19hr. In the Interceptor mission, at 32kg TOW, the parallel HEPS configuration has an endurance/TOW of 1.3[hr/kg] compared to 1.15[hr/kg] for the gasoline aircraft. This result yields a 13% increase in endurance from 36.8hr for gasoline to 41.6hr for the parallel HEPS. Finally, in the Communications Relay mission, the gasoline configuration is recommended for all TOW above 28kg as it has the highest loiter endurance. / Graduate
3

Performance Assessment of Electrical Motor for Electric Aircraft Propulsion Applications : Evaluation of the Permanent Magnet Motor and its Limitations in Aircraft Propulsion

Beckman, Mathias, Christy Gerald Volden, Alex January 2019 (has links)
This thesis project will evaluate which kind of electrical motor is best suited for aircraft propulsion and which parameters effect the efficiency. An economic analysis was conducted, comparing the fuel price (Jet A1) for a gas turbine and the electricity price for an electric motor of 1MW. The study was conducted by using analytical methods in MATLAB. Excel was used to compile and present the data. The data used in this thesis project were assumed with regards to similar studies or pre-determined values. The main losses for the Permanent Magnet Synchronous Motor (PMSM) were calculated to achieve a deeper understanding of the most important parameters and how these parameters need to improve to allow for future electric propulsion systems. The crucial parameters for the losses were concluded to be the temperature, voltage level, electrical frequency, magnetic flux density, size of the rotor and rotational speed. The three main losses of a PMSM was illustrated through the analytical equations used in MATLAB. The calculations present how the ohmic losses depend on the temperature (0-230°C) at different voltages (700V and 1000V), how the core losses depend on frequency (0-1000Hz) at different magnetic flux densities and how the windage losses depend on rotational speed (7000-10000 rpm). It could be concluded that at 8500 rpm an efficiency of 91,26% could be achieved at 700V, 1.5T and 90.4% at 1000V, 1.65T. The decrease in efficiency is a result of the increase in magnetic flux density. When looking at the economic viability of electrical integration the power to weight ratio and energy price was compared for the gas turbine and electrical motor including an inverter and battery. This resulted in a conclusion that a pure electrical system may not compete with a gas turbine in 30 years of time due to the low energy density of the battery. It was also concluded that the emissions during cruise could be lowered significantly. If the batteries were charged in Sweden the emissions would decrease from ~937 kg CO2 to ~31 kg CO2. If the batteries were charged in the Nordic region the emissions would decrease to ~119kg CO2. However, if the batteries were to be charged in the US the carbon dioxide emission would be ~1084 kg CO2, which is an increase in CO2 emission compared to the gas turbine.
4

Entwicklung eines Berechnungsprogramms für disruptive hybrid-elektrische Flugantriebe

Wiegand, Marcus 30 May 2023 (has links)
Die Reduktion klimaschädlicher Emissionen ist ein wesentliches Ziel im modernen Luftverkehr. Dafür geeignete Ansätze stellen unter anderem emissionsoptimierte Flugprofile sowie der Einsatz hybrid-elektrischer Antriebstechnologien dar. Um damit verbundene Vorteile identifizieren und quantifizieren zu können, wurde am Lehrstuhl für Turbomaschinen und Flugantriebe der TU Dresden ein modularisiertes 1D-Triebwerksmodell entwickelt, welches die Leistungsrechnung und die Emissionen thermischer Flugantriebe im Auslegungspunkt sowie Off-Design (quasi-stationär) abbilden kann. Im Rahmen dieser Forschungsarbeit wird zunächst die Validierung des bestehenden Modells vertieft und dieses um ausgewählte thermische Triebwerksarchitekturen erweitert. Dabei stehen die Emissionsberechnung und der Off-Design-Betrieb aller Triebwerkskomponenten im Fokus. Von besonderer Bedeutung und Hauptteil der Arbeit ist die Integration hybrider Antriebskonzepte am Triebwerk selbst sowie hinsichtlich notwendiger Komponenten wie bspw. E-Maschinen und Batterie. Teil dessen ist die Literaturrecherche der Funktionsweise und die Ausarbeitung von Modellierungsansätzen zur Umsetzung hybrid-elektrischer Teilkomponenten und deren Verknüpfung zu Triebwerksarchitekturen. Die Implementierung und Validierung für stationäre On- und Off-Design-Berechnungen ist wesentlicher Bestandteil der Arbeit. Das entwickelte Triebwerksmodell kann für die vergleichende Betrachtung ausgewählter Triebwerksarchitekturen und Flugzyklen angewendet werden und liefert somit eine Grundlage für de-ren Optimierung. Der Brennstoffverbrauch und entstehende Emissionen können für verschiedene Triebwerke und Flugmissionen konkret ausgerechnet und abgeschätzt werden. Die Ergebnisse dienen als Grundlage für die Entwicklung neuer hocheffizienter Triebwerke. Dies ermöglicht die gezielte Reduzierung von Emissionen im Luftverkehr für konventionelle sowie für revolutionäre, fortschrittliche und noch in der Entwicklung befindliche Triebwerke.:Problem Zielstellung Methodik Ergebnisse Zusammenfassung
5

Viability of Power-Split Hybrid-Electric Aircraft under Robust Control Co-Design

Bandukwala, Mustafa January 2021 (has links)
No description available.
6

Inlet Shape Considerations for Split-Wing Electric Distributed Propulsion

Papathakis, Kurt Vonderhaar 01 June 2015 (has links) (PDF)
This thesis aims to uncover preliminary design relationships for an inlet of a split-wing electric distributed propulsion regional airliner. Several aspects of the inlet design were investigated, including: the overall thickness of the airfoil section with respect to the chord, inlet throat area, and lip radius. These parameters were investigated using several angles of attack and mass flow rates through the fan. Computational fluid dynamics, with a 2nd Order turbulence model was used and validated against World War II era data from NACA, as those studies were the most pertinent wind tunnel data available. Additionally, other works by Boeing, Empirical Systems Aerospace (ESAero), Rolling Hills Research, and the Air Force Research Laboratories (AFRL) were considered as part of this design tool tradespace. Future work considerations include utilizing an airfoil section designed for M = 0.6 or 0.65 cruise conditions as opposed to a symmetrical airfoil section, extruding the 2-D airfoil section discussed in this thesis for 3-D effects, and incorporating fan rotational physics into the simulations to better account for inlet Mach number effects.

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