Partial automation for calibration routines in the wind tunnel
Flow field measurements of all three velocity components in wind tunnels are needed for the optimization of rotor blades for wind energy and of propellers for the electrification of aviation. Therefore, stereoscopic particle image velocimetry (sPIV) measurements in a wind tunnel should become more time-efficient and accurate. In sPIV measurements, particles are added to the flow and their motion is detected within a laser light sheet distorted in perspective via two cameras. By means of a camera calibration, the geometric relations between the cameras and the measuring plane are determined in order to derive the three velocity components from the particle movements detected by both cameras. During calibration, a calibration target must first be precisely aligned to the light sheet and then specifically tilted for images from both cameras. The alignment of the target is usually done manually, which is quite time-consuming and error-prone. In order to enable a more precise and also faster calibration, a motorized semi-automated calibration is to be developed. Optimal criteria for the set target inclinations are to be researched and used. Finally, the extent to which the measurement uncertainty of the sPIV measurements can be minimized will be quantified.