Hydraulic variable orifice created by circular tube and round insert
The Annular Orifice block annular leakage in a fully-developed laminar flow created by a circular tube and a round insert in an isothermal liquid network. The insert can be located off-center from the tube by an eccentricity value.
The flow rate is computed using the Hagen-Poiseuille equation (see ):
|ν||Fluid kinematic viscosity|
Use this block to simulate leakage path in plungers, valves, and cylinders.
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 . Positive signal at the physical signal port
increases or decreases the overlap, depending on the value of the parameter
Basic Assumptions and Limitations
Fluid inertia is not taken into account.
- Orifice radius
The radius of the tube. The default value is
- Insert radius
The radius of the insert. The default value is
The distance between the central axes of the insert and the tube. The parameter can be a positive value, smaller than the difference between the radius of the tube and the radius of the insert, or equal to zero for coaxial configuration. The default value is
- Initial length
Initial overlap between the tube and the insert. The parameter must be positive. The value of initial length does not depend on the orifice orientation. The default value is
- Orifice orientation
The parameter is introduced to specify the effect of the control signal on the orifice overlap. The parameter can be set to one of two options:
Positive signal increases overlapor
Negative signal increases overlap. The default value is
Positive signal increases overlap.
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.
Physical signal port that controls the insert displacement.
 Noah D. Manring, Hydraulic Control Systems, John Wiley & Sons, 2005