【摘要】：管道輸送在天然氣、水等資源的輸送方面具有其獨(dú)特的優(yōu)勢,但由于人為等因素破壞或管道自身缺陷,不可避免地會(huì)發(fā)生泄漏。由于輸送管道通常被安裝在地下而且延綿數(shù)千里,使得人們無法通過直接接觸管道而對(duì)泄漏進(jìn)行檢測和定位。本文研究所基于的負(fù)壓波法,可以通過監(jiān)測管道首末端的壓力變化趨勢,判斷管道是否發(fā)生泄漏并進(jìn)一步定位泄漏位置。研究中發(fā)現(xiàn),影響泄漏定位精度的因素有很多,其中負(fù)壓波波速和彎頭對(duì)定位精度的影響特別大。因此,本文在原有的負(fù)壓波泄漏檢測及定位系統(tǒng)中,新增了輔助壓力傳感器,用于測定當(dāng)?shù)夭ㄋ?且著重研究了彎頭曲率半徑對(duì)泄漏定位的影響。本文主要分析了含氣率、溫度對(duì)波速的影響,設(shè)計(jì)了測定波速的實(shí)驗(yàn)方案;比較了均值濾波、中值濾波和小波濾波對(duì)壓力信號(hào)的降噪效果;分析了小波變換法、互相關(guān)法以及最大斜率法對(duì)于提取壓力信號(hào)奇異點(diǎn)的優(yōu)缺點(diǎn);研究了泄漏孔大小、泄漏孔位置、管道進(jìn)口壓力、采樣周期對(duì)泄漏檢測靈敏度及定位精度的影響;采用CFD方法對(duì)管道泄漏孔附近的流場進(jìn)行了模擬,分析了泄漏孔附近的速度場、壓力場和湍流強(qiáng)度場,分析了不同泄漏孔大小、不同管道進(jìn)口壓力時(shí)的泄漏信號(hào);分析了流體流經(jīng)彎頭后的壓力變化,分析了負(fù)壓波在不同曲率半徑的管道彎頭里的衰減規(guī)律,分析了彎頭曲率半徑對(duì)泄漏定位精度的影響。結(jié)果表明小波濾波的效果優(yōu)于均值濾波和中值濾波;相比于互相關(guān)法和最大斜率法,采用小波分析法捕捉信號(hào)奇異點(diǎn)不僅準(zhǔn)確而且可以判斷出奇異點(diǎn)的屬性。泄漏孔越大、進(jìn)口壓力越大、采樣周期越小、泄漏孔位置越靠近管道的中間并遠(yuǎn)離彎頭時(shí),其泄漏檢測的靈敏度及定位精度就越高;泄漏信號(hào)隨著泄漏孔和進(jìn)口壓力的增大而變強(qiáng);彎頭曲率半徑為管道直徑的3倍或4倍時(shí),其泄漏定位的精度較好。
[Abstract]:Pipeline transportation has its unique advantages in the transportation of natural gas, water and other resources, but it will inevitably leak due to the damage of man-made factors or the defects of the pipeline itself. Because pipelines are usually installed underground for thousands of miles, it is impossible to detect and locate leaks through direct contact with pipelines. In this paper, the negative pressure wave method based on this method can be used to monitor the pressure change trend at the end of the pipe head, to determine whether the leakage occurs in the pipeline and to locate the leakage position further. It is found that there are many factors that affect the accuracy of leak location, especially the velocity of negative pressure wave and the elbow. Therefore, in the original negative pressure wave leak detection and location system, a new auxiliary pressure sensor is added to measure the local wave velocity, and the effect of curvature radius of the elbow on the leakage location is emphatically studied. This paper mainly analyzes the influence of gas content and temperature on wave velocity, designs the experimental scheme of measuring wave velocity, compares the effect of mean filter, median filter and wavelet filter on the noise reduction of pressure signal, and analyzes the wavelet transform method. The advantages and disadvantages of cross-correlation method and maximum slope method for extracting singularity point of pressure signal are studied, and the effects of leak hole size, leak hole location, pipeline inlet pressure, sampling period on leak detection sensitivity and location accuracy are studied. The CFD method is used to simulate the flow field near the leak hole. The velocity field, pressure field and turbulence intensity field near the leak hole are analyzed, and the leakage signals with different leakage hole sizes and different inlet pressures are analyzed. The pressure variation of fluid flow through the bend is analyzed, the attenuation law of negative pressure wave in the pipe bend with different curvature radius is analyzed, and the influence of curvature radius of the bend on the accuracy of leak location is analyzed. The results show that the effect of wavelet filtering is better than mean filter and median filter, compared with cross-correlation method and maximum slope method, wavelet analysis method can not only capture the singularity of the signal accurately but also judge the attribute of the singularity point. The larger the leak hole, the greater the inlet pressure, the smaller the sampling period, the higher the sensitivity and positioning accuracy of leak detection when the leak hole is closer to the middle of the pipe and far away from the elbow. When the curvature radius of the elbow is 3 times or 4 times of the diameter of the pipe, the accuracy of the leak location is better.
【學(xué)位授予單位】：浙江理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：U178

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