金属材料由于传热快, 温度在短时间内容易达到热平衡。因此, 用红外热像仪测量金属模型转捩难度大。在中国空气动力研究与发展中心(CARDC)Φ3.2 m低速风洞中, 采用在金属模型表面喷涂隔热涂料的方法, 用红外热像仪测量旋翼翼型的温度分布, 通过温度跃变判断转捩位置。一般情况下, 红外热像仪放置在试验段某个位置固定不动。模型改变攻角时, 需要转动模型支撑机构, 这样会造成红外图像中的模型位置发生改变, 不利于比较不同攻角下的转捩位置。为解决该问题, 在模型转动平台上设计了红外热像仪固定装置, 实现了红外热像仪与模型的同步转动, 解决了模型不同攻角状态下模型外形成像的差异问题。红外图像与实物坐标对应更为准确, 获得的模型转捩位置更为精准。

Due to fast heat conduction of metals, the thermal equilibrium state can be reached within a short period of time, which causes a significant difficulty in measuring the transition of metal models when using infrared thermal imager. To solve the problem, an alternative method was presented in this paper by CARDC (China Aerodynamics Research and Development Center) to spray the thermal-insulating coating on the surface of a metal rotor airfoil model in the Φ3.2 m low speed wind tunnel. Then the infrared thermal imager can be used to measure the temperature distribution, and the transition position of model can be determined through the temperature jump. Since the infrared thermal imager was usually fixed to the test section, therefore, when adjusting the angle of attack, the position of model varied in the obtained infrared images, making it inconvenient to compare the transition positions. Thus, the infrared thermal imager was fixed to the rotating platform during the experiment, to synchronize with the rotation of the model, which eliminated the position difference of model images under different angles of attack. In this way, a highly accurate transition position and a more precise mapping between the infrared thermal images and model coordinates were obtained.