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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721036660
Category :
Languages : en
Pages : 32
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Book Description
This paper explains why high resolution design spaces encourage traditional airfoil optimization algorithms to generate noisy shape modifications, which lead to inaccurate linear predictions of aerodynamic coefficients and potential failure of descent methods. By using auxiliary drag constraints for a simultaneous drag reduction at all design points and the least shape distortion to achieve the targeted drag reduction, an improved algorithm generates relatively smooth optimal airfoils with no severe off-design performance degradation over a range of flight conditions, in high resolution design spaces parameterized by cubic B-spline functions. Simulation results using FUN2D in Euler flows are included to show the capability of the robust aerodynamic shape optimization method over a range of flight conditions.Li, Wu and Padula, SharonLangley Research CenterHIGH RESOLUTION; SHAPE OPTIMIZATION; VARIATIONAL PRINCIPLES; PARAMETER IDENTIFICATION; ROBUSTNESS (MATHEMATICS); COMPUTATIONAL FLUID DYNAMICS; AIRFOILS; AERODYNAMIC COEFFICIENTS; DRAG REDUCTION; FLIGHT CONDITIONS; EULER EQUATIONS OF MOTION; LIFT; MULTIDISCIPLINARY DESIGN OPTIMIZATION; ALGORITHMS
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721036660
Category :
Languages : en
Pages : 32
Get Book Here
Book Description
This paper explains why high resolution design spaces encourage traditional airfoil optimization algorithms to generate noisy shape modifications, which lead to inaccurate linear predictions of aerodynamic coefficients and potential failure of descent methods. By using auxiliary drag constraints for a simultaneous drag reduction at all design points and the least shape distortion to achieve the targeted drag reduction, an improved algorithm generates relatively smooth optimal airfoils with no severe off-design performance degradation over a range of flight conditions, in high resolution design spaces parameterized by cubic B-spline functions. Simulation results using FUN2D in Euler flows are included to show the capability of the robust aerodynamic shape optimization method over a range of flight conditions.Li, Wu and Padula, SharonLangley Research CenterHIGH RESOLUTION; SHAPE OPTIMIZATION; VARIATIONAL PRINCIPLES; PARAMETER IDENTIFICATION; ROBUSTNESS (MATHEMATICS); COMPUTATIONAL FLUID DYNAMICS; AIRFOILS; AERODYNAMIC COEFFICIENTS; DRAG REDUCTION; FLIGHT CONDITIONS; EULER EQUATIONS OF MOTION; LIFT; MULTIDISCIPLINARY DESIGN OPTIMIZATION; ALGORITHMS
Author: Bernhard Eisfeld
Publisher: Springer Science & Business Media
ISBN: 3642361854
Category : Science
Languages : en
Pages : 344
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Book Description
This volume reports results from the German research initiative MUNA (Management and Minimization of Errors and Uncertainties in Numerical Aerodynamics), which combined development activities of the German Aerospace Center (DLR), German universities and German aircraft industry. The main objective of this five year project was the development of methods and procedures aiming at reducing various types of uncertainties that are typical of numerical flow simulations. The activities were focused on methods for grid manipulation, techniques for increasing the simulation accuracy, sensors for turbulence modelling, methods for handling uncertainties of the geometry and grid deformation as well as stochastic methods for quantifying aleatoric uncertainties.
Author: American Institute of Aeronautics and Astronautics
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 1380
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 786
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Author: Paul G. Constantine
Publisher: SIAM
ISBN: 1611973864
Category : Computers
Languages : en
Pages : 105
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Book Description
Scientists and engineers use computer simulations to study relationships between a model's input parameters and its outputs. However, thorough parameter studies are challenging, if not impossible, when the simulation is expensive and the model has several inputs. To enable studies in these instances, the engineer may attempt to reduce the dimension of the model's input parameter space. Active subspaces are an emerging set of dimension reduction tools that identify important directions in the parameter space. This book describes techniques for discovering a model's active subspace and proposes methods for exploiting the reduced dimension to enable otherwise infeasible parameter studies. Readers will find new ideas for dimension reduction, easy-to-implement algorithms, and several examples of active subspaces in action.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 34
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Book Description
Free-form shape optimization of airfoils poses unexpected difficulties. Practical experience has indicated that a deterministic optimization for discrete operating conditions can result in dramatically inferior performance when the actual operating conditions are different from the - somewhat arbitrary - design values used for the optimization. Extensions to multi-point optimization have proven unable to adequately remedy this problem of "localized optimization" near the sampled operating conditions. This paper presents an intrinsically statistical approach and demonstrates how the shortcomings of multi-point optimization with respect to "localized optimization" can be overcome. The practical examples also reveal how the relative likelihood of each of the operating conditions is automatically taken into consideration during the optimization process. This is a key advantage over the use of multipoint methods.
Author:
Publisher:
ISBN:
Category : Space vehicles
Languages : en
Pages : 64
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Author: Chi-Keong Goh
Publisher: Springer Science & Business Media
ISBN: 354088050X
Category : Mathematics
Languages : en
Pages : 399
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Book Description
The application of sophisticated evolutionary computing approaches for solving complex problems with multiple conflicting objectives in science and engineering have increased steadily in the recent years. Within this growing trend, Memetic algorithms are, perhaps, one of the most successful stories, having demonstrated better efficacy in dealing with multi-objective problems as compared to its conventional counterparts. Nonetheless, researchers are only beginning to realize the vast potential of multi-objective Memetic algorithm and there remain many open topics in its design. This book presents a very first comprehensive collection of works, written by leading researchers in the field, and reflects the current state-of-the-art in the theory and practice of multi-objective Memetic algorithms. "Multi-Objective Memetic algorithms" is organized for a wide readership and will be a valuable reference for engineers, researchers, senior undergraduates and graduate students who are interested in the areas of Memetic algorithms and multi-objective optimization.
Author: Leifur Leifsson
Publisher: World Scientific
ISBN: 1783266309
Category : Technology & Engineering
Languages : en
Pages : 444
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Book Description
Computer simulations is a fundamental tool of the design process in many engineering disciplines including aerospace engineering. However, although high-fidelity numerical models are accurate, they can be computationally expensive with evaluation time for a single design as long as hours, days or even weeks. Simulation-driven design using conventional optimization techniques may be therefore prohibitive.This book explores the alternative: performing computationally efficient design using surrogate-based optimization, where the high-fidelity model is replaced by its computationally cheap but still reasonably accurate representation: a surrogate. The emphasis is on physics-based surrogates. Application-wise, the focus is on aerodynamics and the methods and techniques described in the book are demonstrated using aerodynamic shape optimization cases. Applications in other engineering fields are also demonstrated.State-of-the-art techniques and a depth of coverage never published before make this a unique and essential book for all researchers working in aerospace and other engineering areas and dealing with optimization, computationally expensive design problems, and simulation-driven design.
Author: Giovanni Petrone
Publisher:
ISBN: 9788866185314
Category : Mathematics
Languages : en
Pages : 212
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Book Description
