大型结冰风洞冰形在线测量系统研制与应用

Investigation and application of ice accretion shape online measurement system for large-scale icing wind tunnel

  • 摘要: 针对大型结冰风洞试验中结冰生长过程三维冰形连续测量需求,研制了基于激光线扫描成像的冰形在线测量系统,并在中国空气动力研究与发展中心3 m×2 m结冰风洞某型飞机机翼模型结冰试验中进行了实际应用。基于三维标定装置,对系统扫描测量过程中的所有激光平面进行了快速标定,获得了相机参数和激光平面参数。针对复杂结冰表面激光线精确提取问题,将Steger方法与梯度重心法进行了有效结合,实现了激光线亚像素精确提取,结合标定结果,解算激光线空间三维坐标,进而重建得到结冰冰形整体三维形貌。试验结果表明,冰形在线测量系统重复测量精度0.18 mm,可有效获取不同云雾环境下模型前缘霜冰、明冰以及混合冰生长过程在不同时刻的三维冰形。与商用三维扫描仪相比,两者结果吻合良好,整体标准偏差0.5 mm。

     

    Abstract: Ice accretion on aircraft surface degrades aircraft's aerodynamic performance and results in unpredictable disasters. Large-scale icing wind tunnels are essential for studying the growth process of the ice accretion on aircraft surfaces, the key to which is obtaining the precise ice shape. In the present paper, we developed a laser line scanning imaging-based system for online measuring the three-dimensional geometry of ice accretion in large-scale icing wind tunnels. This system has been successfully demonstrated in tests using an aircraft wing model at China Aerodynamics Research and Development Center's 3 m×2 m icing wind tunnel. Prior to scanning, a tridimensional calibration device was used to acquire all laser plane coefficients, which were later combined with camera calibration parameters to establish a mapping function between image and real-world dimensions. Using a combination of the Steger method and gradient barycenter calculation, we accurately located the laser lines on the intricate ice surface and calculated its three-dimensional coordinates, which were used to reconstruct the entire three-dimensional ice geometry. Experimental results indicate that our measurement system has a repeatability accuracy of 0.18 mm; it can effectively capture the three-dimensional geometry of rime, mixed and clear ice on the airfoil model's leading edge during the growth process. Our results agree well with commercial 3D scanners, with an overall standard deviation of 0.5 mm.

     

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