| 1. |
- 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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| 2. |
- Jouannet, Christopher, et al.
(författare)
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Design and Flight Testing of a Solar Powered Aircraft, a Student Challenge
- 2013
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The presented work considers designing, building and flight testing a solar poweraircraft as a student project. The goal is to allow student to participate in an aircraft projectfrom design to flight test in order to acquire aircraft design knowledge from theoretical andpractical means. A first theoretical part consists of creating a sizing program for studyingdifferent concepts. Then the gathered knowledge will result in the realization of a flyingdemonstrator. This was realized during a student project over a 5 month period
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| 3. |
- Meirelles, Luiz, 1974, et al.
(författare)
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Effect of hydroxyapatite and titania nanostructures on early in vivo bone response
- 2008
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Ingår i: Clinical Implant Dentistry and Related Research. - : Wiley. - 1708-8208 .- 1523-0899. ; 10:4, s. 245-254
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Hydroxyapatite or titania nano structures were applied on smooth titanium implant cylinders. The aim was to investigate whether nano HA may result in enhanced osseointegration compared to nano titania structures. Material and Methods: Surface topography evaluation included detailed characterization of nano size structures present at the implant surface combined with surface roughness parameters at the micro- and nano- meter level of resolution. Microstructures were removed from the surface to ensure that bone response observed was dependent only on the nanotopography and/or chemistry of the surface. Early in vivo bone response (4 weeks) evaluation was investigated in a rabbit model. Results: In the present study, nano titania coated implants showed an increased coverage area and feature density, forming a homogenous layer compared to nano HA implants. Bone response observed at 4 weeks could not be explained by the surface chemistry. New formed bone connected to the original cortical bone demonstrated an increase of 24% for the nano titania compared to the nano HA implant, although the difference was not statistically significant. Conclusion: Thus, no evidence of enhanced bone formation to nano hydroxyapatite modified implants was observed compared to nano titania modified implants. The presence of specific nano structures; dependent on the surface modification exhibiting different size and distribution did modulate in vivo bone response.
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| 4. |
- Melin, Tomas, 1975-
(författare)
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DESIGN OF UNMANNED AIR SYSTEMS FOR USE IN SEARCH AND RESCUE IN THE NORTH ATLANTIC
- 2012
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A comparison of aircraft performance and program costs involved with unmanned air vehicle (UAV) projects has been performed. The assessment has been taken from a systems engineering point of view when designing a new unmanned air system for a search and rescue case study. Two different design strategies were investigated, one being a traditional aircraft system with servicing and maintenance intervals and the other being a single use aircraft system. The design paradigm is design-to-objective, whilst optimizing for cost.The primary objective is to assess the size of a search and rescue scenario to determine when a single use expendable system becomes more cost effective than a traditional reusable design. To be able to holistically assess the operational effectiveness of the search and rescue system, aircraft subsystems and the system level need to be modeled.
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| 5. |
- Melin, Tomas, 1975-
(författare)
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Multidisciplinary Design in Aeronautics, Enhanced by Simulation-Experiment Synergy
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis covers some aspects of current aircraft design, and presents how experiment and simulation are used as tools. Together they give enhanced effects over employing either one separately. The work presented has been produced using both simulations and experiments. An overview of aircraft design tools is presented, together with a description of their application in research. Participation in two major design projects, HELIX and the Rescue wing, gave an opportunity to combine traditional experimental and computational tools. They also serve as a platform for developing two new tools, the vortex lattice program Tornado and the DoTrack camera based wind tunnel measurement system. The HELIX project aimed at exploring new, unconventional high-lift systems, such as blown flaps, flaperons and active vortex generators. The concepts were investigated with an array of conceptual design tools, ranging from handbook methods to high Reynold’s number wind tunnels. The research was done in several stages. After each stage the concepts failing to reach specifications were discontinued. The active vortex generator concept is followed in detail from the first phase in the HELIX project, and was finally evaluated by full computational fluid dynamics (CFD) and wind tunnel testing. The lessons learned in HELIX were applied to the Rescue wing project, where a kite balloon system for emergency localization was developed. The project is truly multidisciplinary, and both experiment and simulation had to be used in close conjunction. Lack of appropriate methods for measurement and analysis of this kind of device meant that new methods had to be developed. Recent experience of academia working closely together with industry has shown substantial benefits to all parties involved. The synergy of computer modeling and simulation with experiment plays an important role in the common collaborative modus operandi of academia and industry. In particular, the later stages of aeronautic educational programmes should actively pursue such collaboration.
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| 6. |
- Melin, Tomas, 1975-
(författare)
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Parametric Airfoil Catalog Part I, Archer A18 to Göttingen 655 : An Aerodynamic and Geometric Comparison Between Parametrized and Point Cloud Airfoils
- 2013. - 1
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- A fundamental part of aircraft design involves wing airfoiloptimization, establishing an outer shape of the wing which has good aerodynamic performance for the design mission, good internal volume distribution for fuel and systems and which also serves as an efficient structural member supporting the load of the weight of the aircraft. The underlying idea with this parametrization is to couple an appropriate number of parameters, balancing the need of geometric accuracy with the necessity of few airfoil parameters in order to facilitate en expedient optimisation, with the intrinsic value of having parameters that makes sense for a human; such as thickness, camber and trailing edge thickness. Several approaches to parametrization of wing proles can be found in the literature. Airfoils can be described by point clouds as done in most airfoil libraries. The number of parameters is twice as large as the number of points used (x and y coordinates) and in the case of aerodynamic optimization this parametrization will most certainly be not well behaved, since no smoothing function is included and must therefore be employed. Other problems may arise for the fact that the airfoils sometimes are defined with too few coordinate points and/or too few decimals, a problem occurring especially with old airfoils. On the other hand, the design space that this kind of parametrization allows representing is extremely large, as any and all shapes can be reproduced, even degenerate ones. Airfoils can also be represented by mathematical functions. Among the most common representatives of thiscategory are indeed the NACA 4-, 5- and 6-digits formulations. Compared to point clouds, they could be said to represent the opposite case: they are very well behaving parametrizations, but they cannot cover avery large design space, since they only provide four to six parameters respectively to be tuned. The NACA 4digit series is particularly interesting as the parametersare a part of the name of the airfoil. In the case of the 5- and 6 digit series, the name is instead constructed from the airfoils aerodynamic characteristic and geometry. Another known set of theoretically defined airfoils are the Joukowski profiles [4]. Using the conformal mapping method, airfoils with a round nose and sharp trailing edge can be represented. Sadly the method is not to recommend for trying to match known airfoils and the design space it describes is quite confined to airfoils with often poor performances.
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| 7. |
- Melin, Tomas, 1975-
(författare)
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Parametric Airfoil Catalog, Part II: Göttingen 673 to YS930 : An Aerodynamic and Geometric Comparison Between Parametrized and Point Cloud Airfoils
- 2013
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- A fundamental part of aircraft design involves wing airfoiloptimization, establishing an outer shape of the wing which has good aerodynamic performance for the design mission, good internal volume distribution for fuel and systems and which also serves as an efficient structural member supporting the load of the weight of the aircraft. The underlying idea with this parametrization is to couple an appropriate number of parameters, balancing the need of geometric accuracy with the necessity of few airfoil parameters in order to facilitate en expedient optimisation, with the intrinsic value of having parameters that makes sense for a human; such as thickness, camber and trailing edge thickness. Several approaches to parametrization of wing proles can be found in the literature. Airfoils can be described by point clouds as done in most airfoil libraries. The number of parameters is twice as large as the number of points used (x and y coordinates) and in the case of aerodynamic optimization this parametrization will most certainly be not well behaved, since no smoothing function is included and must therefore be employed. Other problems may arise for the fact that the airfoils sometimes are defined with too few coordinate points and/or too few decimals, a problem occurring especially with old airfoils. On the other hand, the design space that this kind of parametrization allows representing is extremely large, as any and all shapes can be reproduced, even degenerate ones. Airfoils can also be represented by mathematical functions. Among the most common representatives of thiscategory are indeed the NACA 4-, 5- and 6-digits formulations. Compared to point clouds, they could be said to represent the opposite case: they are very well behaving parametrizations, but they cannot cover avery large design space, since they only provide four to six parameters respectively to be tuned. The NACA 4digit series is particularly interesting as the parametersare a part of the name of the airfoil. In the case of the 5- and 6 digit series, the name is instead constructed from the airfoils aerodynamic characteristic and geometry. Another known set of theoretically defined airfoils are the Joukowski profiles [4]. Using the conformal mapping method, airfoils with a round nose and sharp trailing edge can be represented. Sadly the method is not to recommend for trying to match known airfoils and the design space it describes is quite confined to airfoils with often poor performances.
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| 8. |
- Melin, Tomas, 1975-, et al.
(författare)
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Parametric wing profile description for conceptual design
- 2011
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Ingår i: CEAS 2011 Proceedings.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A fundamental part of aircraft design involves the wing airfoil optimization, establishing an outer shape of the wing which has good aerodynamic performance, good internal volume distribution for fuel and systems and which also serves as an efficient structural member supporting the weight of the aircraft. As for all optimization tasks, the complexity of the problem is directly coupled to the parameterization of the geometry. Of highest relevance are the number of parameters and the number of additional constraints that are required to ensure valid modeling.This paper proposes a parameterization method for two dimensional airfoils, aimed at providing a wide design space, while at the same time keeping the number of parameters low. With 15 parameters defining the wing profile, many of the existing airfoils can be modeled with close tolerance.Several approaches to parameterization of wing profiles can be found in the literature. Airfoils can be described by point clouds as done in most airfoil libraries [1]. The number of parameters is twice as large as the number of points used (x and y coordinates) and in the case of aerodynamic optimization this parameterization will most certainly be not well behaved, since no smoothing function is included and must therefore be added. Other problems may arise for the fact that the airfoils sometimes are defined with too few coordinate points and/or too few decimals, a problem occurring especially with old airfoils. On the other hand, the design space that this kind of parameterization allows representing is extremely large, as any and all shapes can be reproduced, even degenerate ones.
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| 9. |
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| 10. |
- Melin, Tomas, 1975-
(författare)
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Validation of a numerical simulation tool for aircraft formation flight
- 2013
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Ingår i: Proceedings of the 4:th CEAS Conference in Linköping 2013. - 9789175195193 ; , s. 623-629
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The use of formation flight for increased fuel efficiency has received a lot of attention in the last couple of years.This paper covers a numerical simulation of a NASA test flight utilizing a formation of two F18A Hornet aircraft. The numerical simulation was made using an adapted version of the vortex lattice method TORNADO, allowing for several aircraft to be simulated in a trimmed condition. The numerical results showed good agreement with the flight test data. Some discrepancies due to the numerical model not covering viscous diffusion was found as expected but not quantified or analyzed.
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