FEATURES OF FORMATION OF PROBING PULSE SIGNALS IN SYSTEMS OF LOW-FREQUENCY ULTRASOUND DIAGNOSIS OF LONG PIPES
DOI:
https://doi.org/10.31471/1993-9981-2022-1(48)-27-35Keywords:
long pipeline, excitation signal, envelope pulse, Henning function.Abstract
The analysis of the essence of the interaction of low-frequency ultrasonic directional wave with the inconsistencies of the pipe wall in the process of diagnosing the technical condition of long pipelines is performed. It is shown that the mechanism of reflection of low-frequency wave from irregularities of the pipe wall of different heights coincides with the mechanism of reflection of sea tidal or storm wave from dams of different heights on land. The general characteristics of information excitation signals for sensing the state of objects in radar and in diagnosing long pipelines are given.The parameter of the resolution of the ultrasonic control system is introduced, which represents the ability of the control system to separately receive and reproduce signals from two or more reflectors, which are closely spaced from each other in the direction of propagation of the directional wave. The presence of the so-called dead zone, which is a section of the pipe from the place of installation of the piezoelectric transducers of the acoustic antenna, in which the echo signal from the discontinuity is not separated from the excited (initial). The presence of a dead zone and its size is an important characteristic of the sensitivity of low-frequency diagnostics of long pipelines by directional waves.First of all, it is important to know the size of the dead zone in the low-frequency oscillation excitation section, because this section will not be monitored. The presence of a dead zone and its size is an important characteristic of the sensitivity of low-frequency diagnostics of the technical condition of long pipelines by directional waves when detecting inconsistencies in the pipe wall.It is established that the use of the Henning function to modulate the excited sinusoidal signal allows to control the duration of the acoustic oscillation train in the pipe wall and input and output transients, which in turn reduces the dead zone duration when diagnosing technical condition of low-frequency pipelines. The form of the envelope pulse of excitation of oscillations in the environment of the wall of the long pipeline in the form of the Henning function is substantiated.
The form of the envelope pulse of excitation of oscillations in the environment of a wall of the extended pipeline in the form of function of Heннing is substantiated.
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