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A Framework for Aerostructural Analysis of Wind Turbine BladesYan, Benjamin 04 January 2012 (has links)
As international growth in wind energy steadily increases and the world gradually moves away from fossil fuels, advanced computational tools are required to produce accurate and fast predictions in wind turbine performance, and to allow efficient design cycles using advanced materials and manufacturing methods. Currently, aerostructural analysis often employs the relatively fast but inaccurate Blade Element Momentum (BEM) theory, while accurate but slower Computational Fluid Dynamics (CFD) methods are generally used for aerodynamic analysis alone.To bridge the gap between speed and accuracy, a 3D panel code, TriPan, was coupled with an advanced structural Finite Element Method (FEM) code, TACS, to perform aerostructural analysis for wind turbine blades. In addition, the framework allows the replacement of the panel solver by higher fidelity solvers to increase the accuracy of the overall aerostructural solution.
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A Framework for Aerostructural Analysis of Wind Turbine BladesYan, Benjamin 04 January 2012 (has links)
As international growth in wind energy steadily increases and the world gradually moves away from fossil fuels, advanced computational tools are required to produce accurate and fast predictions in wind turbine performance, and to allow efficient design cycles using advanced materials and manufacturing methods. Currently, aerostructural analysis often employs the relatively fast but inaccurate Blade Element Momentum (BEM) theory, while accurate but slower Computational Fluid Dynamics (CFD) methods are generally used for aerodynamic analysis alone.To bridge the gap between speed and accuracy, a 3D panel code, TriPan, was coupled with an advanced structural Finite Element Method (FEM) code, TACS, to perform aerostructural analysis for wind turbine blades. In addition, the framework allows the replacement of the panel solver by higher fidelity solvers to increase the accuracy of the overall aerostructural solution.
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Aerostructural Analysis and Design Optimization of Composite AircraftKennedy, Graeme 17 December 2012 (has links)
High-performance composite materials exhibit both anisotropic strength
and stiffness properties. These anisotropic properties can be used to
produce highly-tailored aircraft structures that meet stringent
performance requirements, but these properties also present unique
challenges for analysis and design. New tools and techniques are
developed to address some of these important challenges. A
homogenization-based theory for beams is developed to accurately
predict the through-thickness stress and strain distribution in thick
composite beams. Numerical comparisons demonstrate that the proposed
beam theory can be used to obtain highly accurate results in up to
three orders of magnitude less computational time than
three-dimensional calculations. Due to the large finite-element model
requirements for thin composite structures used in aerospace
applications, parallel solution methods are explored. A parallel
direct Schur factorization method is developed. The parallel
scalability of the direct Schur approach is demonstrated for a large
finite-element problem with over 5 million unknowns. In order to
address manufacturing design requirements, a novel laminate
parametrization technique is presented that takes into account the
discrete nature of the ply-angle variables, and ply-contiguity
constraints. This parametrization technique is demonstrated on a
series of structural optimization problems including compliance
minimization of a plate, buckling design of a stiffened panel and
layup design of a full aircraft wing. The design and analysis of
composite structures for aircraft is not a stand-alone problem and
cannot be performed without multidisciplinary considerations. A
gradient-based aerostructural design optimization framework is
presented that partitions the disciplines into distinct process
groups. An approximate Newton--Krylov method is shown to be an
efficient aerostructural solution algorithm and excellent parallel
scalability of the algorithm is demonstrated. An induced drag
optimization study is performed to compare the trade-off between wing
weight and induced drag for wing tip extensions, raked wing tips and
winglets. The results demonstrate that it is possible to achieve a 43%
induced drag reduction with no weight penalty, a 28% induced drag
reduction with a 10% wing weight reduction, or a 20% wing weight
reduction with a 5% induced drag penalty from a baseline wing obtained
from a structural mass-minimization problem with fixed aerodynamic
loads.
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Aerostructural Analysis and Design Optimization of Composite AircraftKennedy, Graeme 17 December 2012 (has links)
High-performance composite materials exhibit both anisotropic strength
and stiffness properties. These anisotropic properties can be used to
produce highly-tailored aircraft structures that meet stringent
performance requirements, but these properties also present unique
challenges for analysis and design. New tools and techniques are
developed to address some of these important challenges. A
homogenization-based theory for beams is developed to accurately
predict the through-thickness stress and strain distribution in thick
composite beams. Numerical comparisons demonstrate that the proposed
beam theory can be used to obtain highly accurate results in up to
three orders of magnitude less computational time than
three-dimensional calculations. Due to the large finite-element model
requirements for thin composite structures used in aerospace
applications, parallel solution methods are explored. A parallel
direct Schur factorization method is developed. The parallel
scalability of the direct Schur approach is demonstrated for a large
finite-element problem with over 5 million unknowns. In order to
address manufacturing design requirements, a novel laminate
parametrization technique is presented that takes into account the
discrete nature of the ply-angle variables, and ply-contiguity
constraints. This parametrization technique is demonstrated on a
series of structural optimization problems including compliance
minimization of a plate, buckling design of a stiffened panel and
layup design of a full aircraft wing. The design and analysis of
composite structures for aircraft is not a stand-alone problem and
cannot be performed without multidisciplinary considerations. A
gradient-based aerostructural design optimization framework is
presented that partitions the disciplines into distinct process
groups. An approximate Newton--Krylov method is shown to be an
efficient aerostructural solution algorithm and excellent parallel
scalability of the algorithm is demonstrated. An induced drag
optimization study is performed to compare the trade-off between wing
weight and induced drag for wing tip extensions, raked wing tips and
winglets. The results demonstrate that it is possible to achieve a 43%
induced drag reduction with no weight penalty, a 28% induced drag
reduction with a 10% wing weight reduction, or a 20% wing weight
reduction with a 5% induced drag penalty from a baseline wing obtained
from a structural mass-minimization problem with fixed aerodynamic
loads.
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Aero-structural Optimization of Divergence-critical WingsMoon, Scott Geoffrey 15 February 2010 (has links)
This study investigates the use of the divergence speed as an additional constraint to a multi-disciplinary optimization (MDO) problem. The goal of the project is to expand the MDO toolbox by adding an aeroelastic module used where the aeroelastic characteristics present a possible safety hazard. This paper examines aeroelastic theory and MDO disciplines. The divergence constraint function is developed on a BAH wing. The optimization problem is executed on the HANSA HFB 320 transport jet using the FEAP structural solver and a Vortex Lattice Method as the aerodynamic solver. The study shows that divergence speed can function as a safety constraint but the stress constraints determine the optimum design. Furthermore, obtaining a true divergence constraint will require a finer mesh, a more efficient aerodynamic solver and non-finite difference approach to gradient determination. Thus, the addition of the divergence constraint does not yet directly benefit this MDO framework.
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Aero-structural Optimization of Divergence-critical WingsMoon, Scott Geoffrey 15 February 2010 (has links)
This study investigates the use of the divergence speed as an additional constraint to a multi-disciplinary optimization (MDO) problem. The goal of the project is to expand the MDO toolbox by adding an aeroelastic module used where the aeroelastic characteristics present a possible safety hazard. This paper examines aeroelastic theory and MDO disciplines. The divergence constraint function is developed on a BAH wing. The optimization problem is executed on the HANSA HFB 320 transport jet using the FEAP structural solver and a Vortex Lattice Method as the aerodynamic solver. The study shows that divergence speed can function as a safety constraint but the stress constraints determine the optimum design. Furthermore, obtaining a true divergence constraint will require a finer mesh, a more efficient aerodynamic solver and non-finite difference approach to gradient determination. Thus, the addition of the divergence constraint does not yet directly benefit this MDO framework.
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Methods for the Aerostructural Design and Optimization of Wings with Arbitrary Planform and Payload DistributionTaylor, Jeffrey D. 01 May 2018 (has links)
The design of an aircraft wing often involves the use of mathematical methods for simultaneous aerodynamic and structural design. The goal of many of these methods is to minimize the drag on the wing. A variety of computer models exist for this purpose, but some require the use of expensive time and computational resources to give meaningful results. As an alternative, some mathematical methods have been developed that give reason ably accurate results without the need for a computer. However, most of these methods can only be used for wings with specific shapes and payload distributions. In this thesis, a hybrid mathematical/computational approach to wing design is developed that can be used for wings of any shape with any payload distribution. Specific mathematical expressions are found to predict the weight and drag for tapered wings and elliptic-shaped wings. The new approach and mathematical expressions are used to find the best distribution of lift on a variety of aircraft wing configurations to minimize drag during flight.
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Distributed Electric Propulsion Conceptual Design Applied to Traditional Aircraft Take Off Distance Through Multidisciplinary DesignMoore, Kevin Ray 23 November 2018 (has links)
While vertical takeoff and landing aircraft show promise for urban air transport, distributed electric propulsion on existing aircraft may offer an immediately implementable alternative. Dis- tributed electric propulsion has the potential of increasing the aircraft thrust-to-weight ratio and lift coefficient high enough to enable takeoff distances of less than 100 meters. While fuel based propulsion technologies generally increase in specific power with increasing size, electric propul- sion typically can be decreased in size without a decrease in specific power. The smaller but highly power-dense propulsion units enable alternative designs including many small units, optionally powered units, and vectored thrust from the propulsion units, which can all contribute to better runway performance, decreased noise, adequate cruise speed, and adequate range. This concep- tual study explores a retrofit of continuously powered, invariant along the wingspan, open bladed electric propulsion units. To model and explore the design space we used a set of validated models including a blade element momentum method, a vortex lattice method, linear beam finite element analysis, classical laminate theory, composite failure, empirically-based blade noise modeling, mo- tor mass and motor controller empirical mass models, and nonlinear gradient-based optimization. We found that while satisfying aerodynamic, aerostructural, noise, and system constraints, a fully blown wing with 16 propellers could reduce the takeoff distance by over 50% when compared to the optimal 2 propeller case. This resulted in a conceptual minimum takeoff distance of 20.5 meters to clear a 50 ft (15.24 m) obstacle. We also found that when decreasing the allowable noise to 60 dBa, the fully blown 8 propeller case performed the best with a 43% reduction in takeoff distance compared to the optimal 2 propeller case. This resulted in a noise-restricted conceptual minimum takeoff distance of 95 meters.Takeoff distances of this length could open up thousands of potential urban runway locations to make a retrofit distributed electric aircraft an immediately implementable solution to the urban air transport challenge.
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Aero-Structural Optimization of a 5 MW Wind Turbine RotorVesel, Richard W., Jr. 19 June 2012 (has links)
No description available.
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Development of a modular MDO framework for preliminary wing designPaiva, Ricardo Miguel 14 December 2007 (has links)
Multidisciplinary Design Optimization (MDO) is an area in engineering design which has been growing rapidly in terms of applications in the last few decades, aircraft design being no exception to that. The application of MDO to aircraft and more
specifically, wing design, presents many challenges, since disciplines like aerodynamics and structures have to be combined and interact. The level to which this interaction is implemented depends only on how much one is willing to pay in terms of
computational cost.
The objective of the current work is therefore to develop a simplified MDO tool,
suitable for the preliminary design of aircraft wings. At the same time, versatility
in the definition of optimization problems (in terms of design variables, constraints
and objective function) is given great attention. At the same time, modularity will
ensure that this framework is upgradeable with higher-fidelity and/or more capable
modules.
The disciplines that were chosen for interaction were aerodynamics and structures/
aeroelasticity, though more data can be extracted from their results in order to
perform other types of analyses. The aerodynamics module employs a Vortex Lattice
code developed specifically for the current implementation of the tool. The structural
module is based on Equivalent Plate model theory. The fluid structure interaction
is simply one-way, wherein the aerodynamics loads are passed on to the structural
analyzer for computation of the static deformation. Semi-empirical relations are then used to estimate the flutter speed. The optimizer, which controls the activity of
the other modules, makes use of a gradient based algorithm (Sequential Quadratic
Programming) to search for a local minimum of a user defined objective function.
Among the myriad of MDO strategies available, two are chosen to exemplify the
modularity of the tool developed: Multidiscipline Feasible (MDF) and Sequential
Optimization (SO), and their results are compared. Several case studies are analyzed
to cover a broad spectrum of the capabilities of the framework.
Because user interaction is of prime concern in design optimization, a graphical interface (GUI) of the tool is presented. Its advantages in terms of the set up of
optimization problems and post-processing of results are made clear.
In conclusion, some topics for future work regarding the expansion and improvement
of the features of the application are noted.
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