Projects / Programmes
Automatic optimisation of aerodynamic surfaces
| Code |
Science |
Field |
Subfield |
| 2.05.05 |
Engineering sciences and technologies |
Mechanics |
Fluid mechanics |
| Code |
Science |
Field |
| P240 |
Natural sciences and mathematics |
Gases, fluid dynamics, plasmas |
| Code |
Science |
Field |
| 2.03 |
Engineering and Technology |
Mechanical engineering |
aerodynamics, optimisation, numerical methods, laminar flow
Researchers (4)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
26345 |
MSc David Eržen |
Engineering sciences and technologies |
Researcher |
2010 - 2012 |
22 |
| 2. |
31462 |
PhD Aleksej Majkić |
Mechanical design |
Researcher |
2010 - 2011 |
36 |
| 3. |
30617 |
Vid Plevnik |
Engineering sciences and technologies |
Researcher |
2010 - 2012 |
0 |
| 4. |
18084 |
PhD Gregor Veble |
Physics |
Head |
2010 - 2012 |
55 |
Abstract
In the proposed project we wish to develop a method for automatic design of three-dimensional surfaces with the use of the panel based vortex methods. The emphasis will be on the quest for an appropriate quantity, which depends on the surface pressure distribution, such that, when minimized, will lead to an optimal flow. The proposed method is a natural extension of the method published in v Gregor Veble, 2008, 'A Parameter Free Cost Function for Multi-Point Low Speed Airfoil Design', CMES-Computer modeling in engineering and sciences 36 243-260, which is intended for the design of laminar two-dimensional wing sections and has already been successfully used in practice for the design of wing sections of the new aircraft of the Pipistrel d.o.o. Ajdovščina company that is currently in development. We wish to extend the ideas of this method to three dimensions.
The optimisation method will be based on the inviscid, incompressible panel method with free vorticity elements. Considering the current computer capabilities, these present the best compromise between the accuracy of results and the computational complexity when dealing with optimisation problems. An own program package for the computation of an ideal fluid around bodies of arbitrary geometries using the panel method will be developed for the needs of the project.
In two dimensions, using the mentioned two-dimensional method, the wing section optimisation is performed by the minimisation of a functional given by the integral of the absolute value of the pressure gradient along the arc-length of the profile. We presume that the procedure can be extended to three dimensions. The functional generalisation that is expected to work and that is the main subject of analyses of the proposed project is the surface integral of the absolute value of the pressure gradient over the wetted surfaces. In two dimensions, this functional is reduced to the known result, whereas in three dimensions we expect it to lead to uniform surface pressure distributions.
After a successful establishment of the numerical method, the functional and the corresponding constraints, the effort will be focused on designing some example aerodynamical surfaces. As a test case we will consider the wing-body junction, which typically presents one of the main sources of aircraft interference drag. The obtained shapes will be tested using the CFD finite volume method as implemented in the open-source package OpenFOAM.
The proposed method will be interesting both from an academic as well as a practical point of view. The pressure distribution functional will represent a novel approach that will be applicable to a wide range of problems outside aircraft design. At the same time, the method will be directly applicable to the design process in the Pipistrel company, where it will enable a rapid optimisation of difficult geometries such as the wing-body junction or the glass-fuselage contact.
Significance for science
The executed project delivers a novel method for rapid design of complex three dimensional surfaces which promote laminar flow and prevent flow separation in areas of turbulent flow. The method is capable of handling geometric constraints. It successfully builds on a method that was previously used for design of two dimensional airfoils and extends those principles to three dimensions. The results are tested using computational fluid dynamic tools, which confirm the utility of the method for problems of design of low drag shapes that occur in aerodynamic design practice.
The method is suitable for use in practical applications, especially in preliminary aerodynamic design phase where it is necessary to quickly evaluate a number of different concepts. The method relies on a simplified method of fluid flow and is therefore much faster than methods that calculate full Reynolds averaged Navier-Stokes equations. At the same time, the method is suitable for design of aerodynamic details at junctions of complex surfaces. The method therefore presents a novel approach towards aerodynamic design, which is suited for rapid form iteration and, despite using a simplified model, promotes aerodynamically efficient flow in practice.
An additional result of the project is a publically available open source package for the calculation of flows around lifting bodies named PolyVort. It allows other researchers and engineers to use it for aerodynamic research and development.
Significance for the country
The success of the executed project is twofold. Primarily, it secured the development of a new approach towards aerodynamic designed, which will improve the competitiveness of Slovene companies that rely on efficient aerodynamic or hydrodynamic design for the development of their products. The results of the project were already presented to other interested parties, and evaluations of the method are already taking place also in development projects of companies not involved in this project. For the co-financer of the project, the method is an additional contribution towards guaranteeing further competitive advantages in the field of design of efficient flying vehicles, which it already possesses on a world-wide scale. The method was already used for design of various aerodynamic surface details.
On the other hand, the importance of this project is also to establish aerodynamic design as a scientific and research discipline that is otherwise poorly represented in Slovenia. Results of the project represent both basic knowledge in this field as well as engineering tools, and therefore open perspectives and possibilities for future development of the discipline in Slovenia.
Most important scientific results
Annual report
2010,
2011,
final report,
complete report on dLib.si
Most important socioeconomically and culturally relevant results
Annual report
2011,
final report,
complete report on dLib.si
