| Resumo : |
Aviation sector is responsible for approximately 2% of anthropogenic greenhouse gases emission. Moreover, this sector is expected to continue growing at a rate of 4 - 5% a year. Thus, the efficiency of the energy conversion processes in an aircraft, as well as the development of new aircraft configurations, due to the oil prices growth and the crisis generated by the Covid pandemic, is essential in the pursuit of a more sustainable aviation sector. The exergy analysis can be helpful to identify points of improvement and assess innovative configurations. This dissertation aim to introduce and extend the exergy concept and analysis in aerodynamic assessment performing a drag breakdown and a flow field analysis using the exergetic method. The main objective is to explore the method as a tool for the aerodynamic assessment of an unpowered configuration. Computational fluid dynamics analysis of the airfoil NACA 0012 at subsonic compressible flow and NACA 2315, NACA 2312 and NACA 2309 at a transonic compressible flow were used as test cases to present the concept. Rates of exergy destruction and a flow field analysis are presented and analyzed along the wake downstream of the airfoil comparing four turbulence models.
The theoretical exergy method is compared with classical near field method and validated with technical reports. Finally, the results show that exergy method in aerodynamics presents a room for improvement, with a drag reduction around 12% on 2D flow field. Finally, the results show that it is possible to reduce the drag by up to 12% in subsonic and transonic regimes, and generate savings of 800W and 3000W respectively. There are no expressive changes of the exergy destroyed with airfoil thickness variation in the transonic regime. Besides Spallart Allmaras turbulence model proves to be fittest in subsonic regime
due the processing time/accuracy relationship while the k -? - SST shows more accuracy in compressible transonic models. |