Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Numerical Study of Airfoil in Near-Stall Conditions
Submission Author:
Renan Trevizan de Melo , SP
Co-Authors:
Renan Trevizan de Melo, Daniel Sampaio Souza, Elmer Gennaro
Presenter: Renan Trevizan de Melo
doi://10.26678/ABCM.COBEM2023.COB2023-1245
Abstract
This research analyzes different flows over an airfoil in order to demonstrate a practical methodology to visualize the formation of laminar separation bubbles (LSB) with interest in characterize its main aspects. It is known that LSB appear as aerodynamic performance limiters in many flows, especially at low Reynolds numbers, and may affect the controllability of air vehicles in near stall conditions. Phenomena such as boundary layer separation, laminar-turbulent transition and vortex shedding are strongly linked to LSB. In this context, the Eppler 387 airfoil was characterized using the XFLR5 software and evaluated via CFD through the OpenFOAM to obtain LSB in a configuration close to the stall, with an angle of attack of 8º for steady state and Reynolds of 4.5×10^4 and 6×10^4. The distributions of pressure (and friction) considering laminar and turbulent flow were compared, identifying the formation of a short LSB (Re = 6×10^4), with a separation at 0.148c and reattachment at 0.464c, and another long bubble (Re = 4.5×10^4), with separation at 0.173c and reattachment at 0.682c (in terms of the airfoil chord, c). Evaluating the behavior of this type of instability can be decisive to understand its transition (bursting phenomena) and optimize prediction and control methods.
Keywords
laminar separation bubbles, Aerodynamic performance, Stall, prediction, control
