Experimental analysis of 1997 Honda Civic VTi rear air diffuser

• Autor(a) principal: Fernandes, Lucas Borges
• Data de Publicação: 2022
• Outros Autores: Fernandes, Vitor Borges
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: eng
• Título da fonte: Repositório Institucional da UFU
• Texto Completo: https://repositorio.ufu.br/handle/123456789/36498
• topic: Aerodynamics; Diffuser; Race car; Wind tunnel; Downforce; Drag; Honda; Civic; CNPQ::ENGENHARIAS::ENGENHARIA AEROESPACIAL::AERODINAMICA

Racing cars have a single purpose, to deliver the best performance on the tracks. Always looking for the best relationship between aerodynamic drag and downforce so that higher speeds on straights and curves are achieved and thus reduce lap times. The installation of aerodynamic devices, such as airfoils, spoilers, vortex generators, air diffusers, among others, are some ways to achieve this objective. The exposure of mechanical and structural components on the underside of the vehicle contributes significantly to the increase in the total drag coefficient, and therefore vehicles modified for competition must have devices that mitigate this phenomenon and at the same time intensify the negative lift coefficient. This work presents an experimental study of the flow around the Honda Civic VTi 1997 modified to participate in time attack competitions. The model was built following the base form of the car, seeking to maintain fidelity to the existing vehicle. In the wind tunnel, tests were carried out with the model on a scale of 1:10, with and without a diffuser, in which the angle of the ascent ramp was varied from 0 to the maximum angle of 10.51, with the interval of 2, totaling 6 settings (0, 2, 4, 6, 8 and 10.51). Later, endplates were installed in the 2, 4, 6 and 8 diffusers. All tests were performed with the model using the smooth floor at a speed of 20 m/s. The parietal tuft visualization method was used to identify the change in flow pattern for each diffuser used at the back of the model. The painting visualization method was also used, with which it was possible to observe the flow detachment points. 22 pressure taps were installed in the upper part of the model to obtain the pressure distribution curve, and thus measurements were carried out for the cases in which the installation of diffusers presented the best results. The 2-degree diffuser presented the best result, allowing a reduction of 6% of the total drag force of the model. When adding the endplates, the results showed that there were no significant changes in the drag coefficient, except for the 6-degree setting, which results in an approximately 5% decrease in drag force when compared to the base model. This work aims to serve as a reference for future analysis and thus performing a numerical study (CFD) and the application of other experimental routines is recommended. The investigation of drag reduction mechanisms and the effects of other geometry modifications is suggested for the next steps.