| CPC G01M 3/2815 (2013.01) [G01F 1/37 (2013.01); F17D 5/02 (2013.01); F17D 5/06 (2013.01); G01F 22/02 (2013.01); G01M 3/007 (2013.01); G01M 3/243 (2013.01); G01M 3/26 (2013.01); G01M 3/28 (2013.01); Y02A 20/15 (2018.01)] | 6 Claims |

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1. A negative pressure wave monitoring based leak detection method of a multipath pipeline network, wherein the method includes following steps:
Step 1): analyzing a propagation velocity of a negative pressure wave in a single straight pipeline to obtain a calculated result of a sound velocity in a thin-walled pipe, the propagation velocity is calculated as below:
![]() wherein, a is the propagation velocity, K is an elastic coefficient of liquid in Pa; ρ is a density of the liquid in kg/m3; δ is a wall thickness of a pipeline in m; D is an inner diameter of the pipeline in m; E is elastic modulus of a pipe, and is about 2.0×1011 Pa for a steel pipe; and C1 is a constraint coefficient of the pipe, which depends on constraint conditions of the pipe, and wherein the calculated result is used for calculating a negative pressure wave propagation time;
Step 2): disposing a plurality of pressure sensors at positions of the pipeline, and marking the pressure sensors at known disposing positions on a pipeline network map;
Step 3): linearly interpolating position coordinates of nodes in the pipeline network to extend pipeline network information; resolving the time that a negative pressure wave signal generated by a leak propagates to each remote treatment units (RTUs) at each position in the pipeline network in sequence, to form a data column, and thus establishing a time delay standard library; and
Step 4): simulating a leak situation, detecting a pipeline pressure waveform by using the RTUs in a current network, and after calculating a difference between the measured arrival time of the negative pressure wave at each position and the time delay standard library as a reference, determining a point corresponding to the data column closest to a measured propagation time delay in the time delay standard library as a leak point, and outputting the position of the leak point.
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