Study of Vortex Structures in 3D Unsteady Aerodynamics using Experiment and Simulation
Lead Research Organisation:
University of Glasgow
Department Name: School of Engineering
Abstract
Vortical structures are amongst the most fascinating aspects of unsteady aerodynamics. Leading-edge vortices in dynamic stall (seen on helicopters and wind turbines), result in violent vibrations and mechanical failure. On the other hand, leading-edge vortices (LEVs) have been credited for being solely responsible for high-lift flight in insects and for providing high lift on aircraft employing delta wings.
In both insect flight and on delta wings, a stationary leading-edge vortex on the airfoil is seen. This is very interesting, as in 2D aerodynamics, it can be mathematically shown that a stable LEV cannot exist and that it would tend to convect over the chord. In 3D however, such stationary LEVs are seen, and the conditions under which they exist are not clear. Experiments and CFD methods have shed some light on vortical structures in 3D, but because of time and expense considerations, these methods cannot be used to study the parameter
space and identify conditions where such favourable LEVs exist.
Dr. Kiran Ramesh has developed a reduced-order discrete vortex method which models leading-edge vortices, but at the same time is computationally inexpensive. In this project, it is proposed to combine this methodology with a vortex-lattice formulation, so as to extend it to 3D. With the method thus developed, a range of wing kinematics and planform shapes will be studied to analyse unsteady vortical behaviour, and identify conditions where stationary LEVs may exist.
Experimental work will be conducted to support the development of the reduced-order method and for validation, using the University of Glasgow's subsonic wind tunnel facilities. A range of generic model configurations will be tested using advanced flow diagnostics (Particle Image Velocimetry, Pressure Sensitive Paints, 3D LDA etc) and a 6 component sting balance.
In both insect flight and on delta wings, a stationary leading-edge vortex on the airfoil is seen. This is very interesting, as in 2D aerodynamics, it can be mathematically shown that a stable LEV cannot exist and that it would tend to convect over the chord. In 3D however, such stationary LEVs are seen, and the conditions under which they exist are not clear. Experiments and CFD methods have shed some light on vortical structures in 3D, but because of time and expense considerations, these methods cannot be used to study the parameter
space and identify conditions where such favourable LEVs exist.
Dr. Kiran Ramesh has developed a reduced-order discrete vortex method which models leading-edge vortices, but at the same time is computationally inexpensive. In this project, it is proposed to combine this methodology with a vortex-lattice formulation, so as to extend it to 3D. With the method thus developed, a range of wing kinematics and planform shapes will be studied to analyse unsteady vortical behaviour, and identify conditions where stationary LEVs may exist.
Experimental work will be conducted to support the development of the reduced-order method and for validation, using the University of Glasgow's subsonic wind tunnel facilities. A range of generic model configurations will be tested using advanced flow diagnostics (Particle Image Velocimetry, Pressure Sensitive Paints, 3D LDA etc) and a 6 component sting balance.
Publications
| Description | A simplified aerodynamic model which accounts for temporal camber variations has been constructed. Simulations of a trailing-edge flap undergoing arbitrary motion can be performed at a very low computational cost, and the effect on unsteady flow features (such as flow separation and vortex shedding) assessed. The developed model provides the groundwork for unsteady flow control by means of a flap. A numerical replica of an existing experimental model (aerofoil-flap configuration) has been constructed to perform CFD simulations. Using the open source software OpenFOAM the accuracy of the theoretical/numerical approach has been examined. A collaboration with researchers from Switzerland is ongoing, which has resulted in a research mobility. |
| Exploitation Route | The knowledge derived from this project might be relevant to several industrial applications, notably in the field of renewable energies: providing guidelines for the design and operation of next-generation flapping/deforming energy harvesting devices. The model created can also benefit the micro aerial vehicles and autonomous underwater vehicles industries: improving the aerodynamic performance under perturbed flight conditions, like gusts encounters, and the propulsion efficiency. |
| Sectors | Aerospace Defence and Marine Energy Environment |
| Description | Mobility Funding Scheme |
| Amount | £2,000 (GBP) |
| Organisation | University of Glasgow |
| Sector | Academic/University |
| Country | United Kingdom |
| Start | 01/2022 |
| End | 04/2022 |
| Description | Numerical and Experimental study of unsteady flows |
| Organisation | Swiss Federal Institute of Technology in Lausanne (EPFL) |
| Country | Switzerland |
| Sector | Public |
| PI Contribution | As part of my research group I am contributing to the numerical analysis of the unsteady flows being studied. |
| Collaborator Contribution | Our partners are working on the dynamics of unsteady flows from an experimental perspective. |
| Impact | - Presentation of results at an international conference with work published in the proceedings. - A journal article in preparation. |
| Start Year | 2020 |