基于容器容性阻尼特性的热红外微小泄漏气密性检测技术研究

Research on Air Tightness Detection Technology of Tiny-leakage from Infrared Images Based on Vessel Capacitive-resistance Damping

针对目前在线零部件检测技术难以定位微小泄漏问题,该文提出基于脉冲外激励源与容性阻尼特性的容器气密性红外检测方法。利用脉冲压力生成泄漏气流温度场的一系列时间序列微分信号,增强泄漏气流发射热能量的离散程度,将像素空间维温度差的特征检测转变为时间维温度场变化率的特征检测。采用常规稳态气源与脉冲激励加压方法的两种实验表明,后者比前者脉冲激励加压法具有更高的检测灵敏度,仅用像素热辐射时间序列的二阶导数算法即可有效识别微小泄漏点,提高了检测的准确性和灵敏度,同时验证了文章所提模型的可信度。

In order to copy with the difficulty raised in the online detection of tiny-leakage for industrial parts by present technology,an air tightness detection method based on external pulsed excitations and the characteristic of vessel’s capacitive-resistance damping was proposed by infrared images.When utilizing the time series differential data set of temperature fields generated by gas flow under pulsed excitation,it enhanced the dispersion degree of emitting thermal energy at leakage point.Thus,the feature detection method usually by the temperature difference on pixel space dimension is transformed into the method by the thermal change rates on pixel time dimension.Two experiments were carried out using the conventional steady-state gas source and the dynamic pulsed excitation method separately.The result shows that the latter has higher detection sensitivity.The tiny-leakage could be identified effectively when only applied the second derivative of pixel thermal radiation time series signal.The accuracy and sensitivity were raised either.At the same time,the proposed model of leakage vessel is verified.