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Real time drag minimization using redundant control surfaces
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Flight Dynamics. (Flight Dynamics)
2006 (English)In: Aerospace Science and Technology, ISSN 1270-9638, E-ISSN 1626-3219, Vol. 10, no 7, 574-580 p.Article in journal (Refereed) Published
Abstract [en]

A method for minimizing the drag of a wind tunnel model with multiple control surfaces is presented. The minimization is performed in the wind tunnel and measurements are performed in real time. Real time measurements introduce difficulties such as noise in the signals, hysteresis and problems with repeatability of the function evaluations. The lack of a numerical function to minimize therefore puts certain demands on the optimization method, and hence a derivative free method, often referred to as a generating set search method, is used. The proposed method is generalized to take both linear equality constraints as well as linear inequality constraints into account. The generating set search method is implemented in the wind tunnel and tests show that the drag can be decreased while satisfying the constraints.

Place, publisher, year, edition, pages
2006. Vol. 10, no 7, 574-580 p.
Keyword [en]
Performance optimization, Real time computing, Wind tunnel testing, Direct search method
National Category
Vehicle Engineering
Identifiers
URN: urn:nbn:se:kth:diva-10953DOI: 10.1016/j.ast.2006.05.002ISI: 000241577500003Scopus ID: 2-s2.0-33749664340OAI: oai:DiVA.org:kth-10953DiVA: diva2:233071
Note
QC 20100720Available from: 2009-08-27 Created: 2009-08-27 Last updated: 2017-12-13Bibliographically 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
2. Real Time Drag Minimization
Open this publication in new window or tab >>Real Time Drag Minimization
2006 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

This thesis focuses on the use of multiple redundant control surfaces to increase performance during flight. There is no clear-cut definition of performance. It may differ between applications, but here, the amount of drag for a given flight condition is used. The work is concentrated on minimizing drag with the use of measurements instead of numerical simulations. Measured data contains noise and there are problems with repeatability and hysteresis. These difficulties are considered and a method for drag minimization during flight is presented.

In the first study the drag minimization algorithm is discussed. Focus is put on describing the implemented method and the treatment of constraints to the optimization problem. The constraints include keeping the lift constant as well as having bounds on the control surface deflections.

In the second work, a more complex wind tunnel model is used to validate the drag optimization algorithm. Drag reduction for different flight conditions is studied, as well as the impact of the number of control surfaces. Different layouts of the control surfaces are also tested. The results show that the constraints are satisfied and that the drag is reduced substantially.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006. 27 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2006:62
Keyword
Aeronautics, optimization, experimental verification
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-4114 (URN)
Presentation
2006-10-11, S40, Teknikringen 8, b.v., Stockholm, 13:00
Opponent
Supervisors
Note
QC 20101116Available from: 2006-09-22 Created: 2006-09-22 Last updated: 2010-11-16Bibliographically approved

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