Coefficient pressure distribution at the test section walls of the TA-2 wind tunnel
Daniel Simão Alves de Lima1; Maria Luisa Collucci da Costa Reis1; Marcos da Silva e Sousa1
1 Instituto de Aeronáutica e Espaço
doi:10.20906/CPS/COB-2015-0856
Resumo
Wind tunnels are experimental facilities designed to simulate flows encountered by aerospace vehicles during real flight. The metrological reliability of the data originating from wind tunnel tests depends on the knowledge of the flow quality in the test section. A calibration test campaign is being carried out at the Subsonic Wind Tunnel number 2 of the Aerodynamics Division of the Institute of Aeronautics and Space, IAE/ALA/TA-2. The purpose of the campaign is to supply information about the TA-2 airflow parameters. The evaluation of the airflow configuration will be done by analysing the pressure distribution at the test section, including regions near the walls, the boundary layer growth and the turbulence level. This paper will present the results of the pressure distribution from the upper and lateral walls, which is the first step of the campaign. The measured parameters are static and dynamic pressure of the airflow, which are the input quantities for the mathematical modelling used for the estimation of the pressure coefficient, which is the output quantity. The measurement of static pressures at the test section walls is accomplished by positioning plates along the superior and inferior walls. Pressure taps located on the plates are connected to pressure scanners to supply local static pressure measurements. Pitot tubes located on the upper wall at the beginning of the test section supply dynamic and total pressure measurements. Data reduction includes the evaluation of the uncertainties associated with the measured quantities, as well as their propagation to the output quantity. The method employed here is the Monte Carlo method. Least squares fitting is applied to the experimental data in order to supply pressure coefficient distribution as a function of longitudinal positions of the test section. The quality of the fit is evaluated by the qui-square quantity. International standardization recommended by metrological organizations is followed for uncertainty evaluation. The calibration curves wi
Palavras-chave: Pressure coefficient; flow quality; wind tunnel; least squares fitting