Gate Valve (IL)
A gate in an isothermal liquid network.
Description
The Gate Valve (IL) unit is a gate valve flow control in an isothermal liquid network. The valve consists of a circular orifice with sharp edges and a circular gate valve of the same diameter. The gate opens or closes according to the offset signal at port S. A positive value retracts the plug and opens the valve.
Opening area
S Gate valve opening pattern
The area open to the flow when the gate retracts is:
where is the value of the Valve orifice diameter parameter.
The area covered by the plug in a partially open valve is:
where is the gate displacement, which is the sum of the signal at the S port and the value of the Gate position when fully covering orifice parameter.
If the offset exceeds the value of the Orifice diameter parameter, the open valve area is equal to the sum of the maximum orifice area and the value of the Leakage area parameter:
For any combination of the S port signal and a gate offset that is less than 0, the minimum valve area is the Leakage area.
Numerical offset smoothing
When the valve is in the nearly open or nearly closed position, it is possible to maintain numerical stability in the simulation by adjusting the Smoothing factor parameter. If the Smoothing factor is not zero, a smooth variation of the gate displacement between 0 and the Valve orifice diameter is provided.
Mass flow equation
Mass conservation equation:
The mass flow rate through the valve is calculated as follows:
where
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- flow coefficient, the value of the Discharge coefficient parameter;
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- is the valve opening area;
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- value of the parameter Cross-sectional area at ports A and B;
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- is the average density of the fluid;
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- pressure difference in the valve .
Critical pressure drop, - pressure drop determined from the value of the critical Reynolds number , given by the Critical Reynolds number parameter, which is the transition point between laminar and turbulent flow:
Pressure loss to account for the pressure drop in the valve due to the reduction in valve area and is calculated as:
Pressure recovery describes the positive change in valve pressure due to an increase in area. To disregard pressure recovery, uncheck the Pressure recovery box. In this case the pressure loss .
Ports
Input
#
S -
gate offset
scalar
Details
Valve gate displacement, in m. A positive value on this port means that the valve is open.
Parameters
Parameters
#
Valve orifice diameter —
bore diameter
m | cm | ft | in | km | mi | mm | um | yd
Details
The diameter of the open orifice of the valve.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Gate position when fully covering orifice —
gate offset
m | cm | ft | in | km | mi | mm | um | yd
Details
The gate offset when the valve is closed. A positive non-zero value indicates a partially open valve when the value at port S is 0. A negative non-zero value indicates an overlapped valve that remains closed at the initial positive offset that is set at port S.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Leakage area —
clearance area in fully closed position
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
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.
| Values |
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| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
#
Cross-sectional area at ports A and B —
area at the inlet or outlet of the valve
m^2 | cm^2 | ft^2 | in^2 | km^2 | mi^2 | mm^2 | um^2 | yd^2
Details
The cross-sectional area at the inlet and outlet ports A and B. This area is used when calculating the mass flow rate through the valve.
| Values |
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| Default value |
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| Program usage name |
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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 valve.
| 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
Upper Reynolds number limit for laminar flow through the valve.
| Default value |
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| Program usage name |
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| Evaluatable |
Yes |
# Smoothing factor — numerical smoothing factor
Details
Continuous smoothing factor that provides 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 |
# Pressure recovery — taking into account the pressure rise during the expansion of the area
Details
Determines whether pressure rise is taken into account when fluid flows from a smaller cross-sectional area to a larger cross-sectional area.
| Default value |
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| Program usage name |
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| Evaluatable |
No |