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Unsteady Viscous-Inviscid Coupling Simulations of Separated Laminar Flows Around 2D Airfoils Rothkegel Ide, José Ignacio ; Dimitriadis, Grigorios in Proceedings of the International Forum on Aeroelasticity and Structural Dynamics, IFASD 2015 (2015, June 29) An interactive boundary layer model has been developed in 2D in order to solve the unsteady flow around an airfoil. The inviscid problem is solved using a panel method, by the discretization of the ... [more ▼] An interactive boundary layer model has been developed in 2D in order to solve the unsteady flow around an airfoil. The inviscid problem is solved using a panel method, by the discretization of the airfoil into linear-varying vortex panels. The solution of the boundary layer equations is carried out using a finite volume scheme. Viscous-inviscid coupling is preformed by imposing a permeation velocity on the skin panels of the airfoil and the addition of a free wake at each separation point. [less ▲] Detailed reference viewed: 31 (6 ULg)Dynamic Stall and Stall Flutter Simulations for a 2D Airfoil Using Viscous-Inviscid Coupling Rothkegel Ide, José Ignacio ; Dimitriadis, Grigorios in Proceedings of the 54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2013, April 10) An interactive boundary layer model has been developed and coupled with a pitch plunge airfoil in 2d in order to solve the unsteady flow around the airfoil when undergoing light dynamic stall. The ... [more ▼] An interactive boundary layer model has been developed and coupled with a pitch plunge airfoil in 2d in order to solve the unsteady flow around the airfoil when undergoing light dynamic stall. The inviscid problem is solved by means of a panel method, by the discretization of the airfoil into vortex panels. The boundary layer is solved in a mixed manner, starting the solution in a direct way by imposing the external velocity and continuing it in an inverse way by imposing the displacement thickness. The solution of the boundary layer equations is carried out using a finite volume scheme. Viscous-inviscid coupling is preformed through the imposition of a permeation velocity on the skin panels of the airfoil and the addition of a free wake at each separation point. [less ▲] Detailed reference viewed: 88 (15 ULg)Experiments on a pitch-plunge wing undergoing limit cycle oscillation Norizham, Abdul Razak ; Rothkegel Ide, José Ignacio ; Dimitriadis, Grigorios in Proceedings of the 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference (2012, April 25) The aeroelastic behaviour of a wing oscillating in the heave and pitch degrees of freedom is examined by means of wind tunnel experiment. The phenomena of interest are classical flutter and limit cycle ... [more ▼] The aeroelastic behaviour of a wing oscillating in the heave and pitch degrees of freedom is examined by means of wind tunnel experiment. The phenomena of interest are classical flutter and limit cycle oscillation. Classical flutter is normally associated with the exponential growth of the response amplitude. Linear flutter theory only predicts the critical flutter speed. Any excitation or disturbance beyond the critical speed is assumed to cause exponential growth in the response amplitude. In contrast, any limited amplitude oscillations occurring post-fultter suggest the existence of nonlinear properties in the system. Such properties can originate from the aerodynamic forces in the form of flow separation and reattachment. On the structural side, damping and stiffness can also contribute nonlinear properties. Furthermore, these nonlinearities can manifest themselves even at pre-flutter conditions, depending on the values of some governing parameter. The focus of the present work is the transformation of classical flutter into stall flutter as the equilibrium angle of attack of heaving and pitching wing is increased. The interaction of stall-related nonlinearity with structural nonlinearities is also of interest. The measured aeroelastic responses are analyzed and the bifurcation behavior of the dynamic system is characterized. Structural responses as well as flow field visualization through Particle Image Velocimetry show the origin of nonlinearity does not solely come from the manifestation of separation and the shedding of vortices, but from the structural nonlinearity which limits the response amplitude. [less ▲] Detailed reference viewed: 129 (10 ULg)Interactive boundary layer calculation of separated flows around 2D airfoils Rothkegel Ide, José Ignacio ; Dimitriadis, Grigorios in Proceedings of the 15th International Forum on Aeroelasticity and Structural Dynamics, IFASD 2011 (2011, June 27) Stall flutter is an important undesirable phenomenon affecting lifting surfaces such as helicopter and wind turbine blades, but is particularly difficult to model. Existing methodologies are not ... [more ▼] Stall flutter is an important undesirable phenomenon affecting lifting surfaces such as helicopter and wind turbine blades, but is particularly difficult to model. Existing methodologies are not universally applicable, and have significant limitations concerning applicability, time of computation and accuracy. This paper presents a method that combines interactive boundary layer with point vortex shedding. It is applied to a NACA0012 airfoil, at different angles of attack in the −40◦ < a < 40◦ range, considering a free flow velocity of 20[m/s]. Results are compared to those obtained at the Goldstein Laboratory of the University of Manchester. [less ▲] Detailed reference viewed: 45 (6 ULg)Model order reduction techniques for thermomechanical systems with nonlinear radiative heat transfer using proper orthogonal decomposition Hickey, Daryl ; Hoffait, Sébastien ; Rothkegel Ide, José Ignacio et al in Proceedings of ISMA 2010 (2010, September) Analysing large scale, nonlinear, multiphysical, dynamical structures, by using mathematical modelling and simulation, e.g. Finite Element Modelling (FEM), can be computationally very expensive ... [more ▼] Analysing large scale, nonlinear, multiphysical, dynamical structures, by using mathematical modelling and simulation, e.g. Finite Element Modelling (FEM), can be computationally very expensive, especially if the number of degrees-of-freedom is high. This paper develops modal reduction techniques for such nonlinear multiphysical systems. The paper focuses on Proper Orthogonal Decomposition (POD), a multivariate statistical method that obtains a compact representation of a data set by reducing a large number of interdependent variables to a much smaller number of uncorrelated variables. A fully coupled, thermomechanical model consisting of a multilayered, cantilever beam is described and analysed. This linear benchmark beam is then extended to incorporate an external box. The nonlinear radiative exchanges between the beam and the external box are analysed and a reduction procedure is proposed for this fully coupled, nonlinear, multiphysical, thermomechanical system. Two alternative approaches to the reduction are investigated, a monolithic scaled approach and a partitioned approach that treats the individual physical modes separately. [less ▲] Detailed reference viewed: 98 (22 ULg)Experiments on a 3-D Flapping and Pitching Mechanical Model Norizham, Abdul Razak ; Rothkegel Ide, José Ignacio ; Dimitriadis, Grigorios in Proceedings of the 2009 International Forum on Aeroelasticity and Structural Dynamics (2009, June) The motivation for this paper is to focus on the better understanding of flapping wing flight, including flapping flight involving high pitching amplitudes. The investigation will be primarily ... [more ▼] The motivation for this paper is to focus on the better understanding of flapping wing flight, including flapping flight involving high pitching amplitudes. The investigation will be primarily experimental. The experiment will utilize a mechanical flapping and pitching wind tunnel model, which is modeled on large migrating birds. The 3-D rectangular wings are forced to flap and pitch sinusoidally in a low speed wind tunnel. The unsteady aerodynamic forces generated are measured using a three-component force balance. The main objective of this work is to investigate the effect that varying the oscillation parameters has on the aerodynamic forces acting on the 3-D wing undergoing flapping and pitching. The parameters in question are reduced frequency, flapping ampli- tude and pitching amplitude. Comparisons are made with aerodynamic force predictions obtained from unsteady vortex lattice calculations. [less ▲] Detailed reference viewed: 127 (9 ULg) |
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