中文摘要：

管道系统的微小泄漏会影响瞬变压力波的波形和衰减特性。用Flowmaster流体仿真软件建立了管道模型,控制阀门小开度快速关闭,使管道内部产生瞬变流动,用短时傅里叶变换对管道泄漏发生前后的压力波信号进行时频分析,提取出前三次谐波分量的归一化幅值,通过指数拟合得到有无泄漏时各谐波分量幅值的衰减率,计算不同谐波分量泄漏衰减率的比值对管道泄漏进行定位。结果表明,用该方法提取的谐波分量可以准确地计算出各次谐波的衰减率,从而提高了泄漏的定位精度并能够检测到0.17%的微小泄漏。

英文摘要：

The minor leaks of pipeline system will affect transient waveforms and its attenuation characteristics. A pipe- line model is built by using fluid simulation software Flowmaster. Short-time Fourier transform is used to analyze the pres- sure signals in time-frequency domain, which are generated by closing the valve partially in a short time for both leak and no-leak case. Damping factors of the first three harmonic components extracted from the time-frequency analysis results are calculated by exponential fitting. The leak position is obtained by calculating the ratios of leak-induced damping rates. The results show that the harmonic components extracted from the time-frequency analysis results can be used to exactly calculate the damping rates, which can improve the accuracy of leak location. The leakage can be as small as 0.17%.