Abstract
This paper describes a method of detecting a leak in a gas-transport tube by an indirect detecting approach. In this method, the tube is regarded as an acoustic tube (like a wind instrument) and the acoustic characteristics are made use of to detect a leak location. When the tube is made up of many unit tubes connected lengthwise and when one end of the tube is excited by an acoustic white noise, the reflection coefficients and cross-section areas of the unit tubes are obtained by the partial auto-correlation of the signal measured at the other end of the tube.
The location is detected by comparing the coefficients or the areas of the unit tubes with leak to those of normal tubes. Namely, if there appears a leak in one of the unit tubes, the coefficient or the area of the unit tube will be different from that of a normal tube. Then the location is found by sensing the difference.
This paper shows a few experimental results. The experiments are performed with two kinds of tubes, under several cases of leak.
(1) The length=60.75m, the diameter=15mmφ, the acoustic damping is large and the diameters of leak are 3mmφ, 1.5mmφ and 1mmφ. The location of 3mmφ and 1.5mmφ are clearly detected, but the 1mmφ leak location is not always clearly detected.
(2) The length=6mφ, the diameter=25mmφ the acoustic damping is less and the diameters of leak are 5mmφ, 3mmφ, 1.5mmφ, 1mmφ and 0.5mmφ.
All cases of leak except 0.5mmφ are detected.
Then it becomes clear that the method can detect a leak location by an indirect detecting approach with a relatively high accuracy.
