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Performance optimization of flexible wings using multiple control surfaces
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics. (Flight Dynamics)
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics. (Flight Dynamics)ORCID iD: 0000-0003-2391-641X
2009 (English)In: International forum on aeroelasticity and structural dynamics, 2009, 1-15 p.Conference paper, Published paper (Other academic)
Abstract [en]

In this study, the performance of a flexible wing with multiple control surfaces is optimized for different flight conditions. A wind tunnel model with 16 independent control surfaces is used as the test case. The problem is posed as a nonlinear optimization problem with the measured drag as the objective. The variables are the control surface deflections and the angle of attack. Using direct measurements and hardware in the optimization loop causes several difficulties such as problems with repeatability and drift in the measured signal. Constraints include maintaining the lift as well as bounds on the control surface deflections and the angle of attack. No computational estimation of the drag is performed. Instead, experimental measurements of the drag are used to perform the optimization during the wind tunnel test using a generating set search method. Including the angle of attack as a variable makes the lift constraint slightly nonlinear. An extension to the generating set search method is discussed and implemented to treat this nonlinearity. The algorithm makes the wing adapt to the current flight condition to improve performance. The experimental evaluation of the method shows that the drag is significantly reduced within a wide range of flight conditions.

Place, publisher, year, edition, pages
2009. 1-15 p.
Keyword [en]
Performance optimization, Nonlinear constraints, Generating set search, derivative-free optimization, drag minimization, wind tunnel testing
National Category
Vehicle Engineering
Identifiers
URN: urn:nbn:se:kth:diva-10954OAI: oai:DiVA.org:kth-10954DiVA: diva2:233072
Note
QC 20100617Available from: 2009-08-27 Created: 2009-08-27 Last updated: 2010-07-20Bibliographically approved
In thesis
1. On improving efficiency of flight using optimization
Open this publication in new window or tab >>On improving efficiency of flight using optimization
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, optimization is used to improve the performance of aircraft. The focus is on operating current generation aircraft more efficiently rather than designing new aircraft. Drag minimization and aircraft trajectory optimization is used to increase efficiency. Optimization methods are implemented and evaluated on different problem formulations.

The first part of the thesis presents a drag minimization strategy using multiple control surfaces distributed across the span of an elastic wing. Aeroelasticity is exploited to reduce drag for a wide range of flight conditions. A method to minimize drag during a long distance flight is developed and tested in a wind tunnel environment. The method is based on continuously changing the control surface deflections to obtain a more beneficial load distribution from a drag point of view for the current flight condition. In a second study, the method is extended to include the angle of attack as a variable together with the control surface deflections in the drag minimization algorithm. Extensive wind tunnel testing demonstrates the possibility to reduce drag significantly with the presented method for a wide range of flight conditions.

The second topic in the thesis is optimizing the aircraft trajectory. The emissions from the aircraft engine are modeled as smooth functions suitable for optimization using published certification data. These emissions are combined in different environmental indices and used as objective functions in the aircraft trajectory optimization problem. The optimization problem is formulated by discretizing the trajectory in time. The resulting large scale nonlinear optimization problem is solved using a sequential quadratic programming method. The trajectory optimization problem is first studied using a model of the Boeing 737 and the results show that the optimal trajectory depends significantly on the definition of the environmental objective function. A method to treat restricted airspace is also presented and evaluated using a model of the Swedish Air Force trainer SK60. The results show that the method for imposing airspace constraints on the flight path works well, especially when the initial point for the optimization is feasible.

 

Place, publisher, year, edition, pages
Stockholm: KTH, 2009. 37 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2009:45
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-10958 (URN)
Public defence
2009-09-22, F3, KTH, Lindstedtsvägen 26, Stockholm, 10:15 (English)
Opponent
Supervisors
Note
QC 20100720Available from: 2009-09-04 Created: 2009-08-27 Last updated: 2010-07-20Bibliographically approved

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Other links

http://www.kth.se/polopoly_fs/1.34556!maj-performance-003.pdf

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Ringertz, Ulf

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