##### Page tree
Go to start of banner

# Pipeline Choke @model

@wikipedia

Relates pressure drop $//$  on the choke with the flowrate through the choke $//$ arising from fluid friction with choke elements (ISO5167):

 (1)

where

 $//$ fluid  density $//$ orifice diameter $//$ pipe diameter $//$ orifice narrowing ratio $//$ $//$ expansion factor

Derivation

Assume steady-state, incompressibleinviscidlaminar flow in a horizontal pipe (no change in elevation) with negligible frictional losses with incharge fluid velocity $//$ and discharge velocity $//$ at the orifice exit.

The mass conservation (equivalent to continuity equation):

 (2)

where

 (3)

Bernoulli's equation reduces to an equation relating the conservation of energy between two points on the same streamline:

 (4)
 (5)
 (6)
 (7)

The above can rewritten as flowrate estimation with a given pressure drop $//$:

 (8)

The actual rate through the orifice with account for the choke/orifice geometry, friction and viscous forces is corrected by introducing the discharge coefficient  $//$:

 (9)

and correction for fluid compressibility is given by expansion factor $//$:

 (10)

# Alternative forms

 (11)
 (12)
 (13)

where

 $//$ fluid mass flowrate $//$$//$ orifice mass flux $//$ orifice cross-section area