被动声学液体管道微泄漏内检测方法研究

Study on internal detection method of small leakage in liquid pipeline based on passive acoustics

针对液体管道微泄漏(小于1 L/min)难以检测和识别的问题,建立基于被动声学的液体管道微泄漏内检测方法,研究管道微泄漏的声学机理,并搭建实验平台。采用管道内置高灵敏度声学传感器的方式,进行不同泄漏孔径和和泄漏内压下微泄漏声学实验,微泄漏声信号幅值随泄漏孔径和泄漏内压呈正相关变化。利用改进EMD(IEMD)-小波阈值降噪算法对微泄漏声信号进行降噪处理,以减少噪声对真实泄漏信号的影响。提取并定义不同信号处理领域(时域、频域)的特征参数,如均值、标准差、均方根、峰峰值等,以表示微泄漏的复杂性。将特征参数作为下一步管道泄漏识别的数据库,并将数据分为实验组和验证组。采用网格参数寻优支持向量机(SVM)构建自动分类模型对管道微泄漏进行识别,降低人工误判概率。研究结果表明:管道微泄漏识别准确率达到97.87%,可以实现对管道微泄漏的准确识别。研究结果可为声学内检测器的研发提供理论基础。

Aiming at the problem that it is difficult to detect and identity the small leakage(less than 1 L/min)of liquid pipeline,a method of internal detecting the small leakage of pipeline based on passive acoustic is established.This paper studies the acoustic mechanism of pipeline micro leakage,the experimental platform of micro leakage detection in pipeline based on passive acoustics is built.The acoustic experiments of small leakage under different leakage aperture and internal pressure are carried out by using a high-sensitivity acoustic sensor built in the pipeline,the amplitude of micro leakage acoustic signal changes positively with the leakage aperture and leakage internal pressure.The IEMD wavelet threshold denoising algorithm is used to denoise the micro leakage acoustic signal to reduce the influence of noise on the real leakage signal.The characteristic parameters of different signal processing fields(time domain and frequency domain),such as mean,standard deviation,root mean square,peak and peak,are extracted and defined to represent the complexity of small leakage.The characteristic parameters are used as the database of pipeline leakage identification in the next step,and the data are divided into experimental group and verification group.The grid parameter optimization support vector mechanism(SVM)is used to build an automatic classification model to identify the small leakage of pipeline and reduce the probability of manual misjudgment.The results show that the accuracy of pipeline small leakage identification is 97.87%,which can realize the accurate identification of pipeline small leakage.The results of this paper can provide a theoretical basis for the development of acoustic internal detector.