Investigating the Possibility of Using the Amplitude-Phase Characteristics of the Turbulent Gas Flow to Diagnose the Gas Pipeline Leakage

In the process of gas pipeline operation, one of the most important activities is to identify the gas leakage. The most difficult is to locate and estimate particularly small outflows. The proposed method uses a model in the form of a difference of phase shifts Δφ(ω) signals and amplitude gain A(ω). To determine the model in the form of amplitude-phase characteristics a test stand with equalizers is used. The signals from the equalizers (r
₁
and r
₂
) and the signals related to the gas pipeline operation: pressure (p
₁
, p
_c
, p
₂
) and mass flow rate (f
₁
, f
₂
) , as well as the simulated mass flow rate of leakages from valves (t
₁
, t
_c
, t
₂
). For these signals their auto and cross power spectral densities are determined (S
_xx
, S
_yr
, S
_yy
, S
_rr
, etc.) which are the basis for determining the spectral transfer function describing the relationship between these signals, which in turn is the basis for determining the amplitude-phase characteristics of the gas flow treated as a closed-loop system, and then the amplitude-phase characteristics of this open-loop system. From the openloop system's amplitude-phase characteristic, the gain and phase margin of this flow are determined. The change of gain and phase margin may be related to changes in the value of leakage (pipeline damage).