| 1. |
- Munjulury, Raghu Chaitanya, et al.
(författare)
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Knowledge-based future combat aircraft optimization
- 2016
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Ingår i: 30th Congress of the International Council of the AeronauticalSciences (ICAS 2016). - Bonn : International Council of Aeronautical Sciences (ICAS). - 9781510834552 ; , s. 273-280
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Konferensbidrag (refereegranskat)abstract
- Future combat aircraft inherently conceal all the components internally essentially for stealth reasons. The geometry is optimized for subsonic and supersonic flight area distribution and the components and payload to be fitted inside the aircraft. The basic requirements to accomplish are fuel consumption, mission profile, and military performance. Analytical methods comprise of a quick aerodynamic and structural optimization. The result obtained is then compared with multi-fidelity aero-structural analysis
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| 2. |
- Abdalla, Alvaro, et al.
(författare)
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The Effect of Engine Dimensions on Supersonic Aircraft Performance
- 2013
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Ingår i: 4:th CEAS Air & Space Conference.
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Konferensbidrag (refereegranskat)abstract
- In aircraft design a critical part of the design isthe engine selection. This is typically making aselection from exiting engines. Looking at a nextgeneration future fighters, however, where thetime of deployment may be 20-30 years in thefuture this is not a valid approach as there willbe an evolution in the engine designs. E.g. anew European fighter aircraft will most likelybe a collaborative project also involving thedevelopment of an engine for that aircraft. Inthis study conceptual engine-airframe co-designis demonstrated, using models of comparablefidelity for both the engine design and theaircraft design. This co-design leads to a deeperunderstanding of the tradeoffs from both sides,and means that also more radical designs andinnovations can be evaluated in a fair way.
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| 3. |
- Munjulury, Raghu Chaitanya, et al.
(författare)
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A comprehensive computational multidisciplinary design optimization approach for a tidal power plant turbine
- 2017
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Ingår i: Advances in Mechanical Engineering. - London : Sage Publications. - 1687-8132 .- 1687-8140. ; 9:3, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- Multidisciplinary design optimization has become a powerful technique to facilitate continuous improvement of complex and multidisciplinary products. Parametric modeling is an essential part with tremendous impact on the flexibility and robustness of multidisciplinary design optimization. This article investigates the effect of relational and non-relational parameterization techniques on the robustness and flexibility of the conceptual design of a multidisciplinary product. Bench marking between relational and non-relational parameterization and their effect on flexibility and robustness indicate that the relational parameterization is an efficient method in the multidisciplinary design optimization process. The inherent properties of the method contribute to an efficient parametric modeling with improved communication between different disciplines. This enhances the performance of the multidisciplinary design optimization process and allows a more flexible and robust design. The considered disciplines are computer-aided design, computational fluid dynamics, finite element analysis, and dynamic simulation. A high-fidelity geometry created in a computer-aided design environment is computer-aided design centric approach and later used in computational fluid dynamics, finite element analysis for a better understanding of the product as it leads to precise outcomes. The proposed approach is implemented for the conceptual design of a novel product, a tidal power plant developed by Minesto AB using a multidisciplinary design optimization process.
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| 4. |
- Munjulury, Raghu Chaitanya
(författare)
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Knowledge-Based Integrated Aircraft Design : An Applied Approach from Design to Concept Demonstration
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The design and development of new aircraft are becoming increasingly expensive and timeconsuming. To assist the design process in reducing the development cost, time, and late design changes, the conceptual design needs enhancement using new tools and methods. Integration of several disciplines in the conceptual design as one entity enables to keep the design process intact at every step and obtain a high understanding of the aircraft concepts at early stages.This thesis presents a Knowledge-Based Engineering (KBE) approach and integration of several disciplines in a holistic approach for use in aircraft conceptual design. KBE allows the reuse of obtained aircrafts’ data, information, and knowledge to gain more awareness and a better understanding of the concept under consideration at early stages of design. For this purpose, Knowledge-Based (KB) methodologies are investigated for enhanced geometrical representation and enable variable fidelity tools and Multidisciplinary Design Optimization (MDO). The geometry parameterization techniques are qualitative approaches that produce quantitative results in terms of both robustness and flexibility of the design parameterization. The information/parameters from all tools/disciplines and the design intent of the generated concepts are saved and shared via a central database.The integrated framework facilitates multi-fidelity analysis, combining low-fidelity models with high-fidelity models for a quick estimation, enabling a rapid analysis and enhancing the time for a MDO process. The geometry is further propagated to other disciplines [Computational Fluid Dynamics (CFD), Finite Element Analysis (FEA)] for analysis. This is possible with an automated streamlined process (for CFD, FEM, system simulation) to analyze and increase knowledge early in the design process. Several processes were studied to streamline the geometry for CFD. Two working practices, one for parametric geometry and another for KB geometry are presented for automatic mesh generation.It is observed that analytical methods provide quicker weight estimation of the design and when coupled with KBE provide a better understanding. Integration of 1-D and 3-D models offers the best of both models: faster simulation, and superior geometrical representation. To validate both the framework and concepts generated from the tools, they are implemented in academia in several courses at Linköping University and in industry
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| 5. |
- Amadori, Kristian, et al.
(författare)
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Multidisciplinary Optimization of Wing Structure Using Parametric Models
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Aircraft design is an inherently multidisciplinary activity that requires integrating different models and tools to reach a well-balanced and optimized product. At Linköping University a design framework is being developed to support the initial design space exploration and the conceptual design phase. Main characteristics of the framework are its flexible database in XML format, together with close integration of automated CAD and other tools, which allows the developed geometry to be directly used in the subsequent preliminary design phase. In particular, the aim of the proposed work is to test the framework by designing, optimizing and studying a transport aircraft wing with respect to aerodynamic, geometry, structural and accessability constraints. The project will provide an initial assessment of the capability of the framework, both in terms of processing speed and accuracy of the results.
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| 6. |
- Baer, Katharina, 1984-
(författare)
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Simulation-Based Optimization of a Series Hydraulic Hybrid Vehicle
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Hybrid transmissions are characterized by their utilization of more than one form of energy storage. They have the potential to help reduce overall fuel consumption and vehicle emissions by providing the possibility of brake energy recuperation and prime mover operation management. Electric hybrids and electric vehicle drives are nowadays ubiquitous, and mechanical energy storage in flywheel has been investigated in the past. The use of fluid power technology with a combustion engine has also been investigated since the late 1970s, and is frequently revisited.Hydraulic hybridization is especially attractive for heavy vehicles with frequent braking and acceleration which benefit most from fluid power components’ high power density, typically busses, delivery or refuse vehicles, and vehicles with existing hydraulic circuits and transmissions, such as forest and construction machinery, but have been considered for smaller vehicles as well.Due to the characteristic discharge profile of hydraulic energy storage, special attention needs to be paid to control aspects in the design process to guarantee drivability of the vehicle. In this respect, simulation models can be of use in early design process stages for cheaper and faster evaluation of concepts and designs than physical experiments and prototyping, and to generate better understanding of the system studied. Engineering optimization aids in the systematic exploration of a given design space, to determine limits and potentials, evaluate trade-offs and potentially find unexpected solutions. In the optimization of a hydraulic hybrid transmission, the integration of component and controller design is of importance, and different strategies (sequential, iterative, bi-level and simultaneous approaches) are conceivable, with varying consequences for the implementation.This thesis establishes a simulation-based optimization framework for a hydraulic hybrid transmission with series architecture. Component and control parameter optimization are addressed simultaneously, using a rule-based supervisory control strategy. The forward-facing dynamic simulation model at the centre of the framework is built in Hopsan, a multi-disciplinary open-source tool developed at Linköping University. The optimization is set up and conducted for an example application of an on-road light-duty truck over standard drive cycles. Both results from these experiments as well as the framework itself are studied and evaluated. Relevant design aspects, such as explicit design relations to be considered and performance requirements for more robust design, are identified and addressed, and the optimization problem is analysed with regard to algorithm performance and problem formulation. The final result is an optimization framework that can be adjusted for further in-depth studies, for example through the inclusion of additional components or optimization objectives, and extendable for comparative analysis of different topologies, applications and problem formulations.
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| 7. |
- 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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| 8. |
- 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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| 9. |
- Hällqvist, Robert, 1983-, et al.
(författare)
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Early Insights on FMI-based Co-Simulation of Aircraft Vehicle Systems
- 2017
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Ingår i: Proceedings of 15:th Scandinavian International Conference on Fluid Power, June 7-9, 2017, Linköping, Sweden. - Linköping : Linköping University Electronic Press. - 9789176853696 ; , s. 262-270
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Modelling and Simulation is extensively used for aircraft vehicle system development at Saab Aeronautics in Linköping, Sweden. There is an increased desire to simulate interacting sub-systems together in order to reveal, and get an understanding of, the present cross-coupling effects early on in the development cycle of aircraft vehicle systems. The co-simulation methods implemented at Saab require a significant amount of manual effort, resulting in scarcely updated simulation models, and challenges associated with simulation model scalability, etc. The Functional Mock-up Interface (FMI) standard is identified as a possible enabler for efficient and standardized export and co-simulation of simulation models developed in a wide variety of tools. However, the ability to export industrially relevant models in a standardized way is merely the first step in simulating the targeted coupled sub-systems. Selecting a platform for efficient simulation of the system under investigation is the next step. Here, a strategy for adapting coupled Modelica models of aircraft vehicle systems to TLM-based simulation is presented. An industry-grade application example is developed, implementing this strategy, to be used for preliminary investigation and evaluation of a cosimulation framework supporting the Transmission Line element Method (TLM). This application example comprises a prototype of a small-scale aircraft vehicle systems simulator. Examples of aircraft vehicle systems are environmental control systems, fuel systems, and hydraulic systems. The tightly coupled models included in the application example are developed in Dymola, OpenModelica, and Matlab/Simulink. The application example is implemented in the commercial modelling tool Dymola to provide a reference for a TLM-based master simulation tool, supporting both FMI and TLM. The TLM-based master simulation tool TLMSimulator is investigated in terms of model import according to the FMI standard with respect to a specified set of industrial needs and requirements.
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| 10. |
- Hällqvist, Robert, 1983-, et al.
(författare)
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Methods for automating model validation : Steady-state identification applied on gripen fighter environmental control system measurements
- 2016
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Ingår i: Proceedings of the 30th congress of the International Council of the Aeronautical Sciences. - : International Council of the Aeronautical Sciences. - 9783932182853
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Konferensbidrag (refereegranskat)abstract
- Model Validation and Verification (V&V) has historically often been considered a final step in the model development process. However, to justify model-based design decisions throughout the entire system development process, a methodology for continuous model V&V is essential. That is, model V&V activities should be fast and easy to reiterate as new information becomes available.Using a high fidelity simulation model of the Environmental Control System (ECS) in the Saab Gripen fighter aircraft as a guiding example, this paper further extends to an existing semiautomatic framework for model steady-state validation developed during ECS model validation efforts. Generic methods for identification of steady-state operation are a prerequisite for steady-state validation of industry grade physics based models against insitu measurements. Four different established methods for steady-state identification are investigated and compared: steady-state conditions on the standard deviation estimated from in-situ measurements, conditions on the variation coefficient, t-test on the slope of a simple regression line, and comparison of differently estimated variances. The methods’ applicability, on ECS measurements in particular, is evaluated utilizing steady-state identification needs defined during Gripen ECS model validation activities.
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