PSI - Issue 59

Ya. Grudz et al. / Procedia Structural Integrity 59 (2024) 750–756

753

4

Ya. Grudz et al. / Structural Integrity Procedia 00 (2019) 000 – 000

coefficients of hydraulic efficiency of network elements on the value of the overall coefficient of hydraulic efficiency, is relevant. The city gas network can be considered as a complex gas transportation system, characterized by multi-thread pipelines with inter-thread jumpers and the presence of road gas selections, which can be permanently active, or buffer, constant in size, or variable in time. For gas pipelines without road selections and emergency gas leaks, the value of the coefficient of hydraulic efficiency is included in the main equation of gas pipelines and can be determined (Grudz et. al. (2012))

Q

E



P P  2

2

p

k

2,5

cd

ZTL





, (9) where Q – actual gas consumption in the gas pipeline; с – a coefficient that depends on the choice of the unit system; d - internal diameter of the gas pipeline; p P , k P - pressures at the beginning and at the end of the gas pipeline;  - theoretical value of the coefficient of hydraulic resistance;  - relative gas density; Z - relative kerosene density; Т – average gas temperature; L - the length of the linear section. If at a distance q l from the beginning there is a concentrated gas sampling or an emergency leak with a flow rate q , then based on (9) we obtain a system of equations

2

2 5 2 ZTLQ





2 P P

2  

p

q

c d E

q

,

2

2 5 2 c d E ZT L l Q q     )( ( q

)

2 P P

2  

q

k

q

(10)

,

where q P - pressure at the point of gas leakage. It is obvious that the coefficient of hydraulic efficiency of the gas pipeline with gas sampling q E will differ to a certain extent from the coefficient of hydraulic efficiency of the gas pipeline without gas sampling Е, Will differ to I certan echtent from the coefficient of hydraulics efficiency of the gas pipeline witgut gas sampling. If we assume that the coefficient of hydraulic efficiency in the area before gas extraction was 1 E , and on the site after selection - 2 E , then the total coefficient of hydraulic efficiency of the section of the gas pipeline with gas sampling q E can be found as a compatible solution of system (10) and equation (9), which gives a dependence for the ratio of the specified coefficients in the form

Q

E



q

2 P P 

2

p

k

2,5

cd

[1(1 /)(1 / )] 2 l L q Q 

ZTL    

(11)

0,5

   

  

2

1 / 

2 E l L q Q / (1 / ) 

l L

E q





2

E

1

2

(12)