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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

Design Optimization of a Regional Transport Aircraft with Hybrid Electric Distributed Propulsion Systems

Rajkumar, Vishnu Ganesh 03 August 2018 (has links)
In recent years, there has been a growing shift in the world towards sustainability. For civil aviation, this is reflected in the goals of several organizations including NASA and ACARE as significantly increased fuel efficiency along with reduced harmful emissions in the atmosphere. Achieving the goals necessitates the advent of novel and radical aircraft technologies, NASA's X-57, is one such concept using distributed electric propulsion (DEP) technology. Although practical implementation of DEP is achievable due to the scale invariance of highly efficient electric motors, the current battery technology restricts its adoption for commercial transport aircraft. A Hybrid Electric Distributed Propulsion (HEDiP) system offers a promising alternative to the all-electric system. It leverages the benefits of DEP when coupled with a hybrid electric system. One of the areas needing improvement in HEDiP aircraft design is the fast and accurate estimation of wing aerodynamic characteristics in the presence of multiple propellers. A VLM based estimation technique was developed to address this requirement. This research is primarily motivated by the need to have mature conceptual design methods for HEDiP aircraft. Therefore, the overall research objective is to develop an effective conceptual design capability based on a proven multidisciplinary design optimization (MDO) framework, and to demonstrate the resulting capability by applying it to the conceptual design of a regional transport aircraft (RTA) with HEDiP systems. / Master of Science / Recent years have seen a growing movement to steer the world towards sustainability. For civil aviation, this is reflected in the goals of key organizations, such as NASA and ACARE, to significantly improve fuel efficiency, reduce harmful emissions, and decrease direct heat release in the atmosphere. Achieving such goals requires novel technologies along with radical aircraft concepts driven by efficiency maximization as well as using energy sources other than fossil fuel. NASA’s all-electric X-57 is one such concept using the Distributed Electric Propulsion (DEP) technology with multiple electric motors and propellers placed on the wing. However, today’s all-electric aircraft suffer from the heavy weight penalty associated with batteries to power electric motors. In the near term, a Hybrid Electric Distributed Propulsion (HEDiP) system offers a promising alternative. HEDiP combines distributed propulsion (DiP) technology powered by a mix of two energy sources, battery and fossil fuel. The overall goal of the present study is to investigate potential benefits of HEDiP systems for the design of optimal regional transport aircraft (RTA). To perform this study, the aerodynamics module of the Pacelab Aircraft Preliminary Design (APD) software system was modified to account for changes in wing aerodynamics due to the interaction with multiple propellers. This required the development of the Wing Aerodynamic Simulation with Propeller Effects (WASPE) code. In addition, a Wing Propeller Configuration Optimization (WIPCO) code was developed to optimize the placement of propellers based on location, number, and direction of rotation. The updated APD was applied to develop the HERMiT 2E series of RTA. The results demonstrated the anticipated benefits of HEDiP technologies over conventional aircraft, and provided a better understanding of the sensitivity of RTA designs to battery technology and level of hybridization, i.e., power split between batteries and fossil fuels. The HERMiT 6E/I was then designed to quantify the benefits of HEDiP systems over a baseline Twin Otter aircraft. The results showed that a comparable performance could be obtained with more than 50% saving in mission energy costs for a small weight penalty. The HERMiT 6E/I also requires only about 38% of the mission fuel borne by the baseline. This means a correspondingly lower direct atmospheric heat release, reduction in carbon dioxide and NOx emissions along with reduced energy consumptions.
2

Regional Transport Aircraft Design using Turbo Electric Distributed Propulsion (TEDiP) System

Polepeddi, Vachaspathy 06 July 2022 (has links)
As the world moves towards environmental sustainability, the civil aviation enterprise has responded by setting challenging goals for significantly increased energy efficiency and reduced harmful emissions into the atmosphere as codified by National Aeronautics and Space Administration (NASA) and Advisory Council for Aircraft Innovation and Research in Europe (ACARE). The airline industry supports these goals because of their positive impact on operational cost and the environment. Achieving such goals requires introduction of novel technologies and aircraft concepts. Previous studies have shown that electrified aircraft can be effective in meeting these challenges.While there are several mechanisms to incorporate novel technologies for electrified aircraft, two such technologies: turbo-electric propulsion and distributed propulsion, are used in this research. Integration of these two technologies with the airframe leverages the well-known favorable interference between the wing and the tractor propeller wake to provide increased lift during takeoff.In the present research, the advantages and disadvantages of integrating a turbo-electric distributed propulsion (TEDiP) system are assessed for a regional transport aircraft (RTA). With near term motor technology, an improvement in trip fuel burn was observed on the four and six propeller variants of the TEDiP aircraft. The takeoff field length(TOFL) also improved in all three design variants which is a direct result of the working of distributed propulsion leading to better aerodynamic performance at takeoff conditions.The approach and findings for this research are reported in this thesis. / Master of Science / While air transportation system is considered the fastest means to travel, the avi-ation industry is responsible for 2.1% of all human-induced CO2 emissions, whichputs a renewed emphasis on environmental sustainability. There is heightenedinterest in exploring alternative propulsion technologies for aviation to mitigatethe effects of ever increasing demand for air travel coupled with fossil fuel pricevolatility.Ambitious plans have been outlined by leading aerospace organizations to reduceharmful emissions into the atmosphere. Achieving these ambitious goals requiresdevelopment and introduction of game changing technologies and aircraft con-cepts. Few such concepts include novel propulsion systems like all electric andhybrid-electric propulsion, distributed propulsion, and boundary layer ingestion.The X-57 is a novel all-electric aircraft being developed by NASA as a technologydemonstrator and makes use of multiple electric motors and propellers placedon the wing.Owing to battery technology limitations, all-electric and hybrid-electric propul-sion are not considered as viable options. In the near term, incorporatingdistributed propulsion alongside turbo-electric propulsion, for a Turbo-ElectricDistributed Propulsion(TEDiP) system may be a promising option in the near--to-mid-term. The overall goal of the present study is to investigate potentialbenefits and penalties of TEDiP systems for regional transport aircraft (RTA).To perform this study, the aerodynamics module of Pacelab Aircraft PreliminaryDesign (APD) Multi-Disciplinary Optimization (MDAO) framework is alteredto account for changes in wing-propeller aerodynamics due to the interactionof wing and multiple propellers. This required selection of a cost-effective toolthat captures aerodynamic data for multiple propellers and wing. VSPAEROis the aerodynamic tool of choice for this research. Aerodynamic data fromVSPAERO is coupled to APD and three TEDiP design variants with four, sixand eight propeller are designed with the ATR 72-500 as the baseline. Thebenefits and penalties of integrating the TEDiP system onto these variants isinvestigatedThe results show that a performance comparable to the baseline can be achievedin the near term with the four propeller variant even with current electricalsystems technology trends with a small weight penalty, and in the medium termon a six propeller variant. A decrease in trip fuel burn and improved takeofffield length(TOFL) performance justifies the usage of TEDiP systems.
3

Quantifying the climate impact of emissions from land-based transport in Germany

Hendricks, Johannes, Righi, Mattia, Dahlmann, Katrin, Gottschaldt, Klaus-Dirk, Grewe, Volker, Ponater, Michael, Sausen, Robert, Heinrichs, Dirk, Winkler, Christian, Wolfermann, Axel, Kampffmeyer, Tatjana, Friedrich, Rainer, Klötzke, Matthias, Kugler, Ulrike 25 September 2020 (has links)
Although climate change is a global problem, specific mitigation measures are frequently applied on regional or national scales only. This is the case in particular for measures to reduce the emissions of land-based transport, which is largely characterized by regional or national systems with independent infrastructure, organization, and regulation. The climate perturbations caused by regional transport emissions are small compared to those resulting from global emissions. Consequently, they can be smaller than the detection limits in global three-dimensional chemistry-climate model simulations, hampering the evaluation of the climate benefit of mitigation strategies. Hence, we developed a new approach to solve this problem. The approach is based on a combination of a detailed three-dimensional global chemistry-climate model system, aerosol-climate response functions, and a zero-dimensional climate response model. For demonstration purposes, the approach was applied to results from a transport and emission modeling suite, which was designed to quantify the present-day and possible future transport activities in Germany and the resulting emissions. The results show that, in a baseline scenario, German transport emissions result in an increase in global mean surface temperature of the order of 0.01 K during the 21st century. This effect is dominated by the CO2 emissions, in contrast to the impact of global transport emissions, where non-CO2 species make a larger relative contribution to transport-induced climate change than in the case of German emissions. Our new approach is ready for operational use to evaluate the climate benefit of mitigation strategies to reduce the impact of transport emissions.
4

Kompaktní město - aneb co nového se může ještě dít v Brně mezi nádražími / Compact City - or what new is able to yet be done in Brno among railway stations

Šuška, Milan January 2010 (has links)
The diploma thesis reacts on the upcoming urban plan for Brno-Jižní centrum. It creates a piece of a real city with some traditional urban spaces and vertically mixed functions. The theory of the creation of the new town quarter is strongly influenced by the reconstruction of Brno railway junction and by the requirement of the incorporation of the city high speed rail connected with Brno region. In the transport concept a new railway tracing is designed enabling to bring all regional trains to the present junction point – Brno main station. This solution will improve a public transport in the city. Moving the route from the Boulevard will make possible an unlimited connection between historical centre and new Jižní centrum. In the design the emphasis is put on a maximal habitability of the area together with application of semi-public residential courts known as “hofjes.” The new public spaces are based on composition principles, optical connection to the historical heart of the city and on linking of urban structures that provide a smart pedestrian connection between the future main railway station and the historical city centre.

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