Design, Construction, Calibration and Testing of a Wind Tunnel Force Balance

September 28, 2020

Experimental activities are essential in the aerospace industry, with wind tunnels being the most used devices in the validation of concepts and design. Therefore, this work aims to endow the Aerospace Engineering Laboratory at Instituto Superior Técnico with an aerodynamic balance capable of measuring forces and moments. The balance follows an existing Stewart platform configuration design, here readjusted to the current requirements. The design and validation of mechanical performance were initially done computationally using SolidWorks, then some experimental tests were performed for verification. In addition to the construction, the instrumentation of the balance was necessary to compute forces and moments, as well as additional quantities for the tests, such as speed, temperature and attitude. To this end, strain gauges and several sensors were studied and implemented. The balance user interface was done in LabVIEW. To make the balance as accurate as possible, a static calibration was performed to relate the application of well-known loads on the balance with the response of the strain gauges. This way, it was possible to obtain a matrix with calibration coefficients for all aerodynamic components using the collected data and the least squares method with a second-order polynomial. Finally, an experimental test was performed with a model of the rear wing of a racing car to confirm the optimisation in CL/CD when using endplates with a curved profile instead of a flat profile. The influence of velocity in the rear wing performance was also analysed and a comparison with CFD was carried out.

Authors in the community:

• 

  A

  André Filipe Rocha Oliveira

  ist190828

Supervisors of this institution:

• 

  J

  João Pedro Ribeiro Marques

  ist176034

• 

  A

  André Calado Marta

  ist31052

mechanical-engineering - Mechanical engineering

eng - English

Instituto Superior Técnico