pressure drop on the choke,
A ratio between compressible fluid volumetric flowrate and incompressible fluid volumetric flowrate through the ideal orifice:
\epsilon = \frac{q_{\rm compressible}}{q_{\rm incompressible}} |
where
q_{\rm incompressible} = \frac{\pi d^2}{4} \cdot \sqrt{\frac{2 \cdot \Delta p}{\rho \cdot (1-\beta^4)}} |
and
pressure drop on the choke, | |
| orifice narrowing ratio | |
| orifice diameter | |
| pipe diameter |
For incompressible fluids and slightly compressible fluid (water and most types of oil) the expansion factor is .
For Strongly Compressible Fluid (condensate, steam and gases) the expansion factor is .
The most popular engineering correlation covering various tapping arrangements is given by ISO5167:
\epsilon = 1 - (0.351 + 0.256 \, \beta^4+ 0.93 \, \beta^8) \cdot \left[ 1 - \left( \frac{p_{out}}{p_{in}} \right)^{1/\kappa} \, \right] |
where
| intake pressure | |
| discharge pressure | |
| orifice narrowing ratio | |
| Isentropic exponent (κ), in express analysis can be taken as ~ 1.3 |
Physics / Fluid Dynamics / Pipe Flow Dynamics / Pipe Flow Simulation (PFS) / Pipeline Choke @model
[ Orifice Plate Discharge Coefficient ]
Pipeline Engineering / Pipeline / Choke