Vision measurement technology research for model angle of attack in wind tunnel tests

A vision measuring technique based on two cameras is developed to measure model angles of attack in wind tunnel tests. Two high-speed industrial cameras with 4 million pixels are used to capture the motion images of the tested model, on the surface of which some high contrast targets are painted. Then the three-dimensional coordinates of the targets are acquired by the solution of the imaging collinear equations. The changes of angle of attack are calculated through the change of the unit vectors of the space lines fitted by the three-dimensional coordinates of the targets. Static validation results on the angle of attack vision measurement system by sophisticated electronic clinometer indicate that the accuracy of the angle of attack vision measurement system is within 0.01°. Dynamic test results on a hinge moment measuring model which is fixed on a sting without main load balance in a 2 m supersonic wind tunnel indicate that the measurement system has good response characteristics and can be used as an effective method for measurement of angle of attack in a high speed wind tunnel, especially for measurement of accurate angle of attack of models and sting elastic angle with the absence of a main load balance.