Hydraulic variable orifice created by circular tube and round insert
The Annular Orifice block models a variable orifice created by a circular tube and a round insert, which may be eccentrically located with respect to the tube. The radial gap between the tube and the insert and its axial length are assumed to be essentially smaller than the insert diameter, causing the flow regime to be laminar all the time. A schematic representation of the annular orifice is shown in the following illustration.
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
S increases or decreases
the overlap, depending on the value of the parameter Orifice
Fluid inertia is not taken into account.
The radius of the tube. The default value is
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 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
The parameter is introduced to specify the effect of the control
signal on the orifice overlap. The parameter can be set to one of
Positive signal increases overlap or
signal increases overlap. The default value is
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