Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
EXPERIMENTAL DRAG REDUCTION ON AHMED BODY BY USAGE OF THE TRIP WIRES AND BY ARRANGEMENTS WITH MICROSPHERE
Submission Author:
Frederico Augusto Braga da Silva , MG
Co-Authors:
Frederico Augusto Braga da Silva, Vagner Ferreira de Oliveira, Guilherme Papini, Rudolf Huebner, Rafael Miranda Hazaña Carvalho, Sarah Thomaz, Luiz Soltz, Matthias Reher
Presenter: Frederico Augusto Braga da Silva
doi://10.26678/ABCM.COBEM2021.COB2021-1565
Abstract
This article presents the studies carried out in the wind tunnel at the Federal University of Minas Gerais in order to verify the effects of the spheres arrangements and trip wires arrangements contributions on the total drag reduction of one proof test Ahmed’s Body. To do this, sets of trip wires were placed at the Ahmed’s Body, over its top surface and over its left and right sides. The spacing between each sphere and each trip wire, and their arrangements, were chosen in order to verify their effects and contribution on drag reduction. A baseline configuration without any devices was established to serve as reference. The best drag reduction result obtained from the experiments was 4% with spaced trip wire relative to baseline. The drag reduction mechanism due to spheres and wires arrangements is resulted from small disturbances on flow with a sequence of small detachments and reattachments of the boundary layer. The global effect is the delaying of the flow main separation, reducing the static pressure difference between the front and rear faces of the Ahmed’s Body, leading to a pressure drag reduction. This mechanism was verified by means of CFD simulations. The friction drag increase due to the spheres and trip wires was evaluated at CFD simulations since it was not measured at experiment. It was verified to be negligible when compared with the total drag reduction obtained with the spheres and trip wires arrangements. In addition, CFD studies were performed in order to validate the Ahmed’s Body simulation model, by the use of the wind tunnel results. The CFD simulations shown good adherence with the experiment, since the drag reduction obtained with simulation was 3.6 %. The validation of the current CFD analyses has demonstrated the utility of this tool to support future wind tunnel tests. The CFD simulations will allow the evaluation of a significant variety of configurations before wind tunnel test runs, saving cost and time expended with prolonged tests with this Ahmed's Body. The data collected from this study has potential application in the automobile, aeronautical, naval, and train transports industries, with positive impacts on economic and environmental parameters.
Keywords
Aerodynamics, Ahmed Body, Automobile, Wind Tunnel, drag reduction, Trip Wires
