Numerical optimization of the suction distribution for laminar flow control aerofoils
Numerical optimization of the suction distribution for laminar flow control aerofoils
In recent years there has been an increasing interest in the search of methods for drag reduction on aircraft. A promising technique for the reduction of the skin-friction drag is to postpone transition from laminar to turbulent flow using either suction - Laminar Flow Control - or suction plus a favourable pressure gradient - Hybrid Laminar Flow Control. However, for an efficient application of these concepts, the suction distribution has to be optimized to ensure that the gain in drag reduction exceeds the power penalty. In this thesis a numerical algorithm has been developed to optimize the suction distribution over several independent suction panels either while maintaining transition at a desired location or while minimizing the overall power consumption.
The numerical code comprises four steps; the calculation of the boundary-layer flow, the determination of the spatial amplification factors of the two-dimensional Tollmien-Schlichting waves, the prediction of the transition location via the eN-method, and finally, the optimization of the suction flow rates. Optimizing the suction distribution while maintaining transition at a desired location can be expressed as a constrained optimization problem, which is solved using an adaptive algorithm based on the gradient projection method. The numerical solution of this problem is very intensive computationally, therefore the use of parallel computation techniques is of advantage. The numerical code has first been applied to flat-plate boundary layers with zero and non-zero pressure gradients and up to eight suction panels, and later to flows over NACA aerofoil sections. Comparison with experimental results has permitted the validation of the code.
The results show that suction is a suitable means for the postponement of transition. The optimum suction distribution has been found to be strongly dependent on the pressure distribution, the configuration of the suction panels and the desired transition location.(DX184260)
University of Southampton
Hackenberg, Petra
ca6ca0f4-627d-4652-8872-9cc9ddb8b76a
1994
Hackenberg, Petra
ca6ca0f4-627d-4652-8872-9cc9ddb8b76a
Hackenberg, Petra
(1994)
Numerical optimization of the suction distribution for laminar flow control aerofoils.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
In recent years there has been an increasing interest in the search of methods for drag reduction on aircraft. A promising technique for the reduction of the skin-friction drag is to postpone transition from laminar to turbulent flow using either suction - Laminar Flow Control - or suction plus a favourable pressure gradient - Hybrid Laminar Flow Control. However, for an efficient application of these concepts, the suction distribution has to be optimized to ensure that the gain in drag reduction exceeds the power penalty. In this thesis a numerical algorithm has been developed to optimize the suction distribution over several independent suction panels either while maintaining transition at a desired location or while minimizing the overall power consumption.
The numerical code comprises four steps; the calculation of the boundary-layer flow, the determination of the spatial amplification factors of the two-dimensional Tollmien-Schlichting waves, the prediction of the transition location via the eN-method, and finally, the optimization of the suction flow rates. Optimizing the suction distribution while maintaining transition at a desired location can be expressed as a constrained optimization problem, which is solved using an adaptive algorithm based on the gradient projection method. The numerical solution of this problem is very intensive computationally, therefore the use of parallel computation techniques is of advantage. The numerical code has first been applied to flat-plate boundary layers with zero and non-zero pressure gradients and up to eight suction panels, and later to flows over NACA aerofoil sections. Comparison with experimental results has permitted the validation of the code.
The results show that suction is a suitable means for the postponement of transition. The optimum suction distribution has been found to be strongly dependent on the pressure distribution, the configuration of the suction panels and the desired transition location.(DX184260)
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Published date: 1994
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Local EPrints ID: 458505
URI: http://eprints.soton.ac.uk/id/eprint/458505
PURE UUID: 52b8a161-6358-40f2-942c-c84e0fb50431
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Date deposited: 04 Jul 2022 16:50
Last modified: 04 Jul 2022 16:50
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Author:
Petra Hackenberg
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