Optical 3d Measurements in Hydrodynamic Tunnel for Aircraft Icing Study

Abstract

Abstract. The study of how aircraft icing influences on aircraft aerodynamic performance is very important for developing measures and recommendation to improve aircraft flight safety. The effective method of aerodynamic processes modeling is experiment in wind (aerodynamic) tunnel or water (hydrodynamic) tunnel. They allow to perform experiments with a scaled model of an aircraft affected by icing and to visualize the wing flow process and changes caused by icing. While visualization of the wing flow yields useful qualitative information about flow, it is more important to retrieve quantitative 3D data of flow, which allows to forecast icing process and to develop anti-icing techniques and recommendations.The presented study addresses to creating an photogrammetric system and 3D measurement techniques for quantitate evaluation of 3D flow parameters in a hydrodynamic tunnel for aircraft icing influence exploration. Being an initial part of a long-term research project, this study is aimed at developing of an accurate calibration technique of the photogrammetric system for 3D measurement in condition of two optical media interfaces. The developed algorithms for imaging process through two optical media interfaces are used in calibration procedure and object 3D coordinates measuring. The results of the photogrammetric system calibration are given in comparison with standard (single media) case. Experimental 3D reconstruction of a typical object demonstrated high accuracy of the developed algorithms.

Image-based System for 3D Visualization of Flow in Hydrodynamic Tunnel

“…Various approaches to optical system calibration for measurement through multimedia optical interfaces can be found in [5,6,7,8], including development of distance dependent distortion or application of special ports for camera [9,10] to reduce refraction effects. A special technique for photogrammetric system calibration directly considering imaging through two media interfaces [11] allows to perform accurate 3D measurements in a hydrodynamic tube. This calibration technique provides not only qualitative but also quantitative characteristics of a flow that are needed for icing process study.…”

“…For applying "Mosca" system for 3D measurements in hydrodynamic tunnel it is necessary to account for a phenomenon of light refraction at interfaces of different optical media. The original techniques for calibration and 3D measurements, based on the detailed analysis of light passing through the different optical media has been developed and evaluated [11]. The developed techniques provide accurate measurements of 3D coordinates in working space 300 × 300 × 300 mm with the accuracy of 0.03 mm.…”