This paper describes a videogrammetric modeldeformation (VMD) measurement system for wind-tunnel testing. The working principles of VMD system are based on non-topographic photogrammetry. Hardware of the system consists of video CCD cameras, a computer with a frame grabber, ~illumination lights, and targets on the model. Software includes schemes of image acquisition, target-tra<kinglcentoid calculation, camera calibration, and data..processing. VMD system can determine accurately the angle-of-attack and aeroelastic deformation of a wind!-tunnel model in real time. As an image-based measurement technique, VMD system has similar technical components to other modern aerodynamic measurement techniques such as pressureand temperature-sensitive paints (PSP and TSP). Model deformation data can be used in several ways to improve the data-reduction process for PSP. Instantaneous model deformation measurements are necessary when PSP is used for pressure measurements in unsteady-aerodynamic and aeroelastic tests. By using deformation data, final PSP results can be mapped onto a deformed model surface, resulting in a more correct representation of the pressure field. Introduction Videogrammetric model-deformation (VMD) and pressure-sensitive paint (PSP) systems are two newlydeveloped optical mpasurement techniques for wind tunnel testing. Based: on the principles of close-range photogrammetry, VMD system determines spatial coordinates of targets on model surface from target centroids in imagei; and then computes model deformation (bendin’g and twist) produced by aerodynamic loads. Model deformation data are essential to understand the aeroelastic properties of a model and ‘l Research Scientist, glember A&4 $ Senior Research Scientist, Member AIAA Copyright
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