Valve Plate Orifice (IL)
Variable valve plate opening in an axial piston machine in an isothermal fluid network.
blockType: EngeeFluids.IsothermalLiquid.Turbomachinery.Auxiliary.ValvePlateOrifice
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Description
Block Valve Plate Orifice (IL) simulates an arc-shaped hole between moving pistons and a pump in an axial piston machine. Rotating pistons are periodically connected to the suction or discharge pipe of the pump through a plate with a hole. Two units can be connected Valve Plate Orifice (IL) to each cylinder of the axial piston pump, to represent the inlet and outlet ports of the pump.
A rotating cylinder with a single arc-shaped groove is connected to the pump inlet in port A and the pump outlet in port B. These points are connected to the plate at an angle ranging from Pressure carryover angle to radian (180 degrees). The angle of rotation of the plate is set by the signal on port G. Cylinder position angle represents the sum of the angle of rotation of the plate and the initial angular displacement , set in the Phase angle parameter:
Angle value It is always in the range from 0 to . For any combination of signal and offset, more I’m glad, the value It is maintained at the level of , and for any combination of signal and offset less than 0 rad, the value It is maintained at level 0. To change the initial position of the hole relative to the groove, you can adjust the Phase angle parameter.
Axial piston machine with five pistons
The image shows the following components of an axial piston machine:
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The valve plate opening.
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The rotor.
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The piston.
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The drive shaft.
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An inclined disk.
Cylinder angle
The rotation of the cylinder relative to the groove is described by the following angles:
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The angle of the cylinder when turning on the groove, :
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The angle of the cylinder when fully rotated to the groove, :
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The angle of the cylinder when turning outside the groove, :
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The angle of the cylinder when fully rotated outside the groove, :
where
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— angle Pressure carryover angle. This angle is the average angular distance that the piston travels during the pressure transition from a closed to an open groove.;
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— half of the parameter value Cylinder orifice diameter;
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— the value of the Cylinder block pitch radius parameter.
The area of the open hole
Calculation of the hole area during cylinder movement
The area of the transition open hole, which is the opening between the angles of rotation of the cylinder and , is calculated as follows:
The area of the transition closed hole, which is the opening between the angles of rotation of the cylinder and , is calculated as follows:
where the opening and closing parameters are defined as:
and
The area between and equal to , and the area between and equal to . The maximum opening of the hole is .
A non-zero value of Smoothing factor provides additional numerical stability when the hole is in an almost closed or almost open position.
Numerically smoothed hole angle
At the angles of entry and exit from the hole, numerical stability can be maintained during modeling by adjusting the value of the Smoothing factor parameter. If the Smoothing factor parameter is not equal to zero, then a smooth change in the transition angle of the opening between is ensured. and and the transitional closing angle between and .
The mass flow equation
The flow rate through the valve plate opening is calculated from the equation relating flow to pressure:
where
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— flow coefficient, the value of the parameter Discharge coefficient;
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— the area of the opening open for the flow;
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— the average density of the liquid;
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— pressure drop on the valve, .
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— critical pressure drop, determined from the value of the critical Reynolds number Critical Reynolds number , which is the transition point between laminar and turbulent fluid flow:
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Ports
Conserving
#
A
—
liquid port
isothermal liquid
Details
The point of entry into the orifice.
| Program usage name |
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#
B
—
liquid port
isothermal liquid
Details
The point of exit from the hole.
| Program usage name |
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Input
#
G
—
cylinder rotation angle, rad
scalar
Details
The angle of rotation of a cylinder in radians, given as a scalar.
| Data types |
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| Complex numbers support |
No |
Parameters
Parameters
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Cylinder block pitch radius —
radius of the initial surface of the cylinder
m | um | mm | cm | km | in | ft | yd | mi | nmi
Details
The radius of the initial surface of a rotating cylinder.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Cylinder orifice diameter —
cylinder groove diameter
m | um | mm | cm | km | in | ft | yd | mi | nmi
Details
Cylinder groove diameter.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Pressure carryover angle —
transient pressure angle
rad | deg | rev | mrad | arcsec | arcmin | gon
Details
The average angular distance travelled by the piston during the period of pressure transition from closed to open groove.
| Units |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Phase angle —
initial plate offset angle
rad | deg | rev | mrad | arcsec | arcmin | gon
Details
Initial plate offset angle. The total angle between the plate and groove is equal to the sum of the Phase angle and Pressure carryover angle, .
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Leakage area —
leakage area through the opening in the fully closed position
m^2 | um^2 | mm^2 | cm^2 | km^2 | in^2 | ft^2 | yd^2 | mi^2 | ha | ac
Details
The sum of all clearances when the valve is in the fully closed position. Any area less than this value equates to the specified leakage area. This parameter contributes to the stability of the numerical solution by maintaining flow continuity.
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| Default value |
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| Evaluatable |
Yes |
# Discharge coefficient — flow coefficient
Details
The correction factor is the ratio of the actual mass flow rate to the theoretical mass flow rate through the orifice.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Critical Reynolds number — upper limit of Reynolds number for laminar flow
Details
The Reynolds number at which the laminar flow regime through the orifice is maintained.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Smoothing factor — numerical smoothing factor
Details
A continuous smoothing factor that provides a smooth opening by correcting the valve characteristic in the nearly open and nearly closed positions. Set a non-zero value less than one to increase the stability of the simulation in these modes.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |