| 1. |
- Grönstedt, Tomas, 1970, et al.
(författare)
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DN Debatt. "Mellanlandning kan halvera utsläppen från Thailandsresa"
- 2018
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Ingår i: Dagens Nyheter. ; , s. 5-
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- I debatten om flyget har det globala perspektivet glömts bort. Risken är att Sveriges bästa möjligheter att minska flygets klimatpåverkan hamnar i skuggan. Det finns nämligen mycket att göra som kan ge effekt redan på kort sikt: vi kan flyga på lägre höjd vid ogynnsamt väder och vi kan välja mindre flygplan och i stället mellanlanda, skriver fem flygforskare.
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| 2. |
- Grönstedt, Tomas, 1970, et al.
(författare)
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Flygforskare: "Våra beräkningar bygger på detaljerade modeller"
- 2018
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Ingår i: Dagens Nyheter (DN). - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- SLUTREPLIK DN DEBATT 4/6. Kenneth Nilsson hävdar i sin replik att vi räknat fel på var gränsen går för att minska koldioxidutsläppen genom mellanlandning. Våra resultat stöds av mer generella studier som kommer nära våra resultat, skriver fem flygforskare.
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| 3. |
- Merkler, Rasmus, et al.
(författare)
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Integration Aspects for Large Generators into Turbofan Engines for a Turbo-electric Propulsive Fuselage Concept
- 2019
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Ingår i: 24th International Symposium on Air Breathing Engines (ISABE 2019). - 9781713818014 ; , s. 536-552
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Konferensbidrag (refereegranskat)abstract
- The present paper discusses some aspects of integrating large generators into turbofan engines for a turbo-electric propulsive fuselage concept (PFC) pursued within the European Commission funded collaborative research project CENTRELINE (“ConcEpt validatioN sTudy foR fusElage wakefiLIng propulsioN intEgration”). In this proof-of-concept project a rear-mounted electric fuselage fan ingests part of the fuselage boundary layer. The fuselage fan is powered by power offtakes from two under-wing podded geared turbofan engines. The enabler to generate the electrical power needed to drive the wake filling aft fuselage fan is a sound integration of a large generator (5MW class) into the under-wing podded turbofan engines. Different integration concepts were compared in a down selection process leading to the most promising concept. For the selected concept the most concept-critical topics are discussed.
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| 4. |
- Raja, Visakha, 1985, et al.
(författare)
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Exploring Influence of Static Engine Component Design Variables on System Level Performance
- 2015
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Ingår i: 22nd International Symposium on Air Breathing Engines, ISABE2015.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- To reach even better operating efficiency and reduced fuel burn, aero engine manufacturers adopt various innovative design methods. Many of the design methods rely on more integrated component and engine design. This makes it necessary for component suppliers such as GKN to be involved more tightly in the design process with the engine integrator. It also necessitates the need for the component developer to predict the effects that its components produce at the engine level so that the designs can be better prepared for future engine architectures. In this paper, an integrated design method is used to make preliminary exploration of the effect of aero-engine static structure design variations on engine performance. Studies were performed on a turbine rear structure (TRS) which is a part of the low pressure (LPT) turbine module. Pressure losses from an aerodynamically well designed TRS (with good LPT outflow match) and a poor LPT outflow matched TRS were coupled to an engine performance model to simulate the effect on engine SFC. The effect on engine SFC due to poor LPT outflow matched TRS coupling is more pronounced than that for aerodynamically well designed TRS. Also pressure drops for an aerodynamically well designed TRS are themselves dependant on structural design variations such as changes in geometrical variables. In this case, the influence of component design variation on SFC is substantial and the relevance of an integrated engine-component design is apparent. Judging from the preliminary findings it can be concluded that additional studies with more variables coupled can reveal further dependencies between engine and the component which are previously un-explored. This seeks to motivate the development of methods to create a multi-level, multi-physics optimization platform for hot engine structures which is the future aim of the project as a part of which this study was conducted.
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| 5. |
- Samuelsson, Sebastian, 1987, et al.
(författare)
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Adaption of a Turbofan Engine for High Power Offtakes for a Turbo-electric Propulsive Fuselage Concept
- 2019
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Ingår i: ISABE 2019 Papers.
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Konferensbidrag (refereegranskat)abstract
- To lower the fuel consumption and its associated emissions, several new aircraft concepts are being investigated. One such concept is the turbo-electric propulsive fuselage concept (PFC) that is being studied in the EU Horizon 2020 project CENTRELINE for a 2035 entry into service (EIS). The PFC makes use of a rear-mounted electric fuselage fan to ingest part of the fuselage boundary layer. The fuselage fan is powered by power offtakes from two under-wing podded geared turbofans. In this paper, a design of the under-wing main power plants is presented and compared to an engine for a conventional reference aircraft with the same EIS year. A free power turbine (PT) stage for the large power offtake required is added aft of the low pressure turbine (LPT). The PT is connected to an electric generator on the same shaft that is integrated in the PT hub. The addition of the PT allows for mechanically decoupling the electric machinery from the LP spool, which is considered beneficial for the electric machinery operation. It also allows for a removal of one LPT stage compared to the reference engine. The power plants for the PFC show a reduction of fan diameter by 11%, as well as a reduction in engine weight of 13% excluding the electric machinery weight.
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| 6. |
- Samuelsson, Sebastian, 1987
(författare)
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Challenges in aero engine performance modeling
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- There is a continuous drive for ever more efficient aero engines due to environmental as well as economical concerns. As the technology of conventional turbofan engines matures, there is a need for new aero engine concepts as well as incremental improvement of existing technologies. In order to improve existing turbofan architectures there is a trend towards integrating the design of the different components in the whole engine system. This creates new challenges both within engine manufacturing companies and between overall equipment manufactures (OEMs) and their suppliers. Methods need to be developed where different component requirements can be balanced against each other for the best performance of the system as a whole. Furthermore, there is a need for multidisciplinary design and optimization, coupling simulations involving several different computational disciplines. In this thesis, a method for consistent conceptual design is presented. In consistent design, the outcomes of the conceptual design are used to iteratively update the assumptions made in the initial thermodynamic cycle calculations until they are consistent. This enables the designer to balance different components against each other. In addition, a first coupling study of a turbine rear structure and whole engine performance is made, indicating the necessity of coupled simulations. Some considerations regarding modeling of engines at conditions far off-design are made. This is needed because some dimensioning mechanical load cases occur at these operating points. Finally, non-hierarchical analytical target cascading is introduced as a method that can be used for coupled optimization during the remainder of this research project.
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| 7. |
- Samuelsson, Sebastian, 1987
(författare)
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Conceptual Design of Propulsion Systems for Boundary Layer Ingestion
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To reduce the climate impact of aviation new aircraft and engine concepts as well as improved design methods are needed. In this thesis, two fronts are explored. The first concerns improved methods for the conceptual design of the engine. A consistent conceptual design approach is presented, where calculated parameters such as stage loadings are used to update the component efficiency assumptions within the cycle optimization loop. The result is that the design space is fully explored, and that pressure ratio is optimally distributed between the components. A coupled analysis of a low pressure turbine and turbine rear structure has also been conducted, showing the importance of considering their coupled interaction when these components are designed. On the second front, concerning the application of the developed methods to new propulsion applications, a conceptual design of a propulsion system for a turbo-electric boundary layer ingesting aircraft concept is presented. The aircraft features and aft-mounted fuselage fan for boundary layer ingestion. Earlier studies have shown a theoretical potential of 10% in power savings compared to a conventional aircraft configuration. The fuselage fan is electrically powered and fed by power offtake from two under-wing mounted geared turbofan engines. To this end, a 5 MW-class generator is integrated into the geared turbofans. The generator is connected to a free power turbine that is introduced to facilitate an optimal generator design and to mechanically decouple the generator from the low pressure shaft. A system-level analysis of the designed propulsion system, including the effects of the boundary layer ingesting fuselage fan shows a fuel burn reduction of 0.6%-3.6%, depending on electric machinery technology, compared to a conventional aircraft in the 2050 time frame. The modest reduction, compared to the theoretical potential, is caused by the difficulty of obtaining a benefit from ingesting the outer part of the boundary layer. This benefit is more than offset by electric machinery losses and the reduced efficiency of the fuselage fan compared to the main engine fan.
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| 8. |
- Samuelsson, Sebastian, 1987, et al.
(författare)
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Consistent Conceptual Design and Performance Modelling of Aero Engines
- 2015
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Ingår i: Proceedings of the ASME Turbo Expo. - 9780791856673 ; , s. V003T06A017-
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Konferensbidrag (refereegranskat)abstract
- During the conceptual design process of an engine, a thermodynamic cycle is initially defined. This is done to ensure that all aircraft requirements, defined in a number of discrete operating points, can be met. Critical component requirements can then be screened off from these operating points underpinning the conceptual design process. As an example, this has traditionally meant that aerodynamic sizing for low specific thrust turbofan engines occurs at top-of-climb and mechanical and temperature constraints are set at take-off.By providing additional parameters indicating the level of technology assumed, such as diffusion factors and stage loadings, a basic geometric representation of the engine can be mapped out as part of the conceptual design process. However, by choosing the parameters representing the component technology levels explicitly, the ability to trade efficiency for weight, or efficiency for cost, becomes less potent. In general, an explicit parameter choice will mean that a suboptimal solution is found.Hence, it makes sense to develop methods that allow including these technology parameters into the conceptual design and performance modeling process in a consistent way. If, for instance, component efficiency is modeled based on turbomachinery stage loading, including the stage loading parameters into the optimization means that the efficiency must be updated based on the stage loading variation. In general, a consistent method requires that conceptual design input is collected in a number of performance operating points, transferred into the conceptual design process and that output from the conceptual design process is returned to the optimizer.To illustrate the consistent conceptual design and performance modeling process, turbomachinery component models are included in the paper, interrelating polytropic efficiency, Reynolds number, size effects and component entry into service. These equations are solved consistently in the conceptual design and performance modeling to establish an optimum year 2020 engine. The method is then further illustrated by comparing the year 2020 engine with two year 2030 engines. The first year 2030 engine is established by an optimization assuming fixed polytropic turbomachinery efficiencies. The other case is defined by assuming the same engine architecture, i.e., the same number of turbomachinery stages as the year 2020 engine. In this case, the efficiency modeling is done using a consistent conceptual design optimization. The consistent optimization produced a more efficient engine despite the fact that the stage numbers were limited to the year 2020 configuration. The benefit is obtained by more thoroughly exploring the pressure ratio distribution between the engine components, as a result of the consistent optimization methodology.
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| 9. |
- Samuelsson, Sebastian, 1987, et al.
(författare)
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Performance analysis of turbo-electric propulsion system with fuselage boundary layer ingestion
- 2021
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Ingår i: Aerospace Science and Technology. - : Elsevier BV. - 1270-9638. ; 109
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Tidskriftsartikel (refereegranskat)abstract
- A propulsion system analysis of an aircraft concept featuring a fuselage tail cone integrated turbo-electrically powered fan is presented. The aircraft has two underwing podded geared turbofan engines and an aft-fuselage mounted boundary layer ingesting fan. The fuselage fan is driven by an electric motor that is powered by power offtake from the main power plants under the wing. A long-range tube-and-wing aircraft with a year 2050 entry into service is used as a reference. A coupled multidisciplinary method for system level assessment of the turbo-electric boundary-layer ingesting propulsion system is presented. A correlation-based method is used to predict fuselage drag and a series of optimizations are carried out for a range of fuselage fan diameters. The optimal level of ingested drag is 30%-57% of the total fuselage drag, resulting in a net reduction in mission fuel burn of 0.6%-3.6% depending on technology assumptions. Further analysis reveals that installation effects, mainly increased mass, offset some of the gains of boundary layer ingestion for the smallest fuselage fan sizes. For larger fan sizes, it is instead the losses in the electric machinery together with the lower efficiency of the fuselage fan, compared to the main engine fan, that compensate for the gains from boundary layer ingestion. However, the by far strongest effect for determining the optimal level of ingested drag is that it is very difficult to obtain a net benefit from ingesting the half of the total fuselage drag contained in the outer part of the boundary layer. The benefit is outweighed by losses in the electric transmission system, installation effects and efficiency deficits of having an aft-mounted fan instead of larger size under-wing main engines. This is true also under the assumption of radical technology such as superconducting electric machinery. It is concluded that the studied aircraft architecture, despite having a high theoretical potential, faces a large difficulty in beneficially ingesting the significant amount of the fuselage drag contained in the outer part of the boundary layer. This severely limits its potential to substantially reduce the fuel burn compared to a conventional twin-engine tube-and-wing aircraft in the year 2050 timeframe.
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| 10. |
- Seitz, Arne, et al.
(författare)
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Concept validation study for fuselage wake-filling propulsion integration
- 2018
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Ingår i: 31st Congress of the International Council of the Aeronautical Sciences, ICAS 2018.
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Konferensbidrag (refereegranskat)abstract
- The present paper provides an overview together with intermediate results of the work-in-progress research performed in the EC-funded Horizon 2020 collaborative project CENTRELINE (“ConcEpt validatioN sTudy foR fusElage wake-filLIng propulsioN integration”), aiming at demonstrating the proof of concept for a groundbreaking approach to synergistic propulsion-airframe integration, the so-called Propulsive Fuselage Concept (PFC). The concept features a turbo-electrically driven propulsive device integrated in the very aft-section of the fuselage, dedicated to the purpose of fuselage wake-filling. Currently at TRL 1-2, CENTRELINE's target is to mature the technological key features of the PFC to TRL 3-4. The core of the targeted proof-of-concept is formed by two experimental test campaigns supported by high-fidelity 3D numerical simulation and integrated multidisciplinary design optimisation techniques for aerodynamics, aero-structures as well as the energy and propulsion system.
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| 11. |
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| 12. |
- Veness, Raymond, et al.
(författare)
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Experience From the Construction of a New Fast Wire Scanner Prototype for the CERN-SPS and its Optimisation for Installation in the CERN-PS Booster
- 2015
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Ingår i: Proceedings of the 4th International Beam Instrumentation Conference, IBIC 2015. ; , s. 479-482
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Konferensbidrag (refereegranskat)abstract
- A new design of wire scanner is under development for the LHC Injector Upgrade project at CERN. A prototype has been designed, built and installed in the SPS accelerator to test the concept in an operational accelerator environment. New technology has been developed and qualified for in-vacuum motor and structural components using 3D metal additive machining. This paper will describe the technology developed for this scanner and the test results to date. This prototype has recently been re-optimised to fit in the limited space available in the PS Booster rings. This design will also be presented.
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| 13. |
- Zhao, Xin, 1986, et al.
(författare)
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Conceptual Mean-line Design of a Low Pressure Turbine for a Geared Turbofan with Rear Structure Interaction
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- One of the most important features of a geared turbofan (GTF) is a reduced number of low pressure turbine (LPT) stages resulting from a faster spinning spool. Compared to a direct drive turbofan (DDTF), in which the LPT normally constitutes a considerable part of the engine total weight, from 10% to more than 25%, dependent on the engine bypass ratio (BPR), fewer stages can cut the weight into half or even less for the LPT. With this benefit, the weight of the LPT alone is no longer a dominating factor for the selection of its configuration. To obtain an optimal LPT configuration for a GTF requires a new balance between weight and performance involving both the LPT and the downstream component, the turbine rear structure (TRS). A conceptual design of the LPT for a mid- to long-range GTF is presented here to clarify this new balance. By comparing a range of designs based on different number of stages and turbine hade angles, the selection of the LPT design for the GTF is described. More importantly, interactions between the LPT design and the TRS design are considered. Results indicate that a joint design is necessary as the TRS plays an important role in designing the LPT of a GTF. It is shown that if the LPT design is done in isolation from the TRS design, a 3-stage LPT performs better than a 4-stage design from a fuel burn perspective. However, when the TRS design is considered, the advantage of the 3-stage LPT design is offset by the associated TRS weight and loss increase, compared to the 4-stage LPT design.
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