Elaboração de modelos semi-empíricos de correção de efeitos de interferência de parede para o arrasto de corpos rombudos para a seção de testes do túnel de vento de circuito fechado da UFMG

Abstract

For experiments and tests carried out in wind tunnels to be reliable, it is essential to understand the effects of wall interference on airflow in the test section with and without aeronautical models, such as solid blockage, wake blockage, buoyancy, and others, in profiles (2D) or scaled-down aircraft models (3D) as well as bluff bodies such as spheres, automotive vehicles, and others. Thus, this research aims to develop specific wall interference correction models for bluff bodies, involving airflow in the test section of the closed-circuit wind tunnel at the Experimental Aerodynamics Laboratory of the Aerospace Engineering course at the Federal University of Minas Gerais. To achieve the main objective, it became necessary to characterize the flow in the test section following an international standard for calibration of subsonic atmospheric wind tunnels, as well as to use theoretical results obtained in previous research involving the same wind tunnel. Pitot tubes, along with ScaniValves transducers, were used for acquiring total and static pressure data at various positions along the entire test section and in the flow "rest" section, as well as the respective total and static temperatures, among other parameters. Thus, empirical correction models for wall interference effects on the drag of bluff bodies were developed from experimentally acquired data. Finally, the proposed empirical models were validated through tests conducted in this work, as well as using data obtained from previous research. The main result obtained indicates that, in general, wall effects for the closed-circuit wind tunnel at UFMG contribute little to the results, amounting to less than 5% of the raw result value. It was concluded that despite the horizontal buoyancy effects and solid and wake blockages showing little influence on the obtained results, the application of the proposed corrections tends to bring them closer to the expected values.