Aerodynamics and structure measurement subsystem for a shape memory alloy actuated adaptive airfoil

Abstract

The aim of this study is to propose a subsystem that is able to establish correlation between aerodynamics and structure measurements to be used as the input to the existing shape memory alloy actuated adaptive airfoil system. A reconfigurable wing with NACA 4412 airfoil was fabricated using Acrylonitrile Butadiene Styrene (ABS) and actuated using SMA spring. A wind tunnel testing was conducted at low Reynolds number with angle of attack ranging from 0° to 12°. Pressure taps were fitted along the upper and lower surface of the airfoil and connected to the multi-tube manometer in order to obtain pressure measurements and strain gauges were mounted in parallel to the pressure taps on the upper surface to measure the deflection of the structure due to the aerodynamics loading. A system to compute the lift and drag coefficients from pressure measurements, was developed using LabVIEW software. The strain of the airfoil structure on the upper surface of the airfoil was measured using strain gauge via the NI 9237 C Series Strain/Bridge Input Module. This measurement was mapped to the pressure distribution around the airfoil to obtain correlation with aerodynamic forces. A strain feedback system with PID controller was used to control the shape of the airfoil using the NI 9263 C Series Voltage Output Module. The work presented here is an extension of work done previously by the authors, and updates the existing adaptive airfoil system with an aerodynamics and wing structure measurements subsystem.