Hydraulic orifice with constant cross-sectional area
The Fixed Orifice block models a sharp-edged constant-area orifice, flow rate through which is proportional to the pressure differential across the orifice. The flow rate is determined according to the following equations:
|pA, pB||Gauge pressures at the block terminals|
|CD||Flow discharge coefficient|
|A||Orifice passage area|
|DH||Orifice hydraulic diameter|
|ν||Fluid kinematic viscosity|
|pcr||Minimum pressure for turbulent flow|
|Recr||Critical Reynolds number|
The block positive direction is from port A to port B. This means that the flow rate is positive if it flows from A to B, and the pressure differential is determined as .
Fluid inertia is not taken into account.
Orifice passage area. The default value is
Semi-empirical parameter for orifice capacity characterization.
Its value depends on the geometrical properties of the orifice, and
usually is provided in textbooks or manufacturer data sheets. The
default value is
The maximum Reynolds number for laminar flow. The transition
from laminar to turbulent regime is assumed to take place when the
Reynolds number reaches this value. The value of the parameter depends
on the orifice geometrical profile. You can find recommendations on
the parameter value in hydraulics textbooks. The default value is
which corresponds to a round orifice in thin material with sharp edges.
Use the Variables tab to set the priority and initial target values for the block variables prior to simulation. For more information, see Set Priority and Initial Target for Block Variables.
Parameters determined by the type of working fluid:
Fluid kinematic viscosity
The block has the following ports:
Hydraulic conserving port associated with the orifice inlet.
Hydraulic conserving port associated with the orifice outlet.