Iconic Diagrams\Hydraulics\Valves\Basic Valves
Domains: Continuous. Size: 1-D. Kind: Iconic Diagrams (Hydraulics).
This model describes a flow control valve with with parasitic volumes.
In this model the flow is modeled by an tanh function. The pressure drop is defined as the pressure where 95% of the desired flow rate is achieved.
dp = pa.p - pb.p
phi = if dp > 0 then
Q_set*tanh( (arctan(0.95)/p_drop) * dp) + GLeak * dp;
else
GLeak * dp
end;
Here phi is the desired flow and p_drop is the 95% pressure drop. Gleak is the conductance of laminar leakage flow when the valve is closed. The pressure at both ports has a lower limit that is equal to the vapour pressure. Therefore the actual equations used in this model are:
p1_lim = if pa.p < p_vapour then p_vapour else pa.p end;
p2_lim = if pb.p < p_vapour then p_vapour else pb.p end;
dp = p1_lim - p2_lim;
Ports |
Description |
pa, pb |
Both terminals of the hydraulic component. |
Causality |
|
fixed volume flow out pa fixed volume flow out pb |
|
Parameters |
|
FlowControlValve\Q_set FlowControlValve\p_drop FlowControlValve\GLeak Va\V Va\B Va\p_initial Vb\V Vb\B Vb\p_initial |
Desired flow [m3/s] pressure drop at 95% flow [Pa] Conductance of the laminar leakage flow [m3/s.Pa], GLeak >= 0! Volume of oil under pressure [m3] (hidden) Effective bulk modulus [Pa] (hidden) The starting pressure of the volume [Pa] (hidden) Volume of oil under pressure [m3] (hidden) Effective bulk modulus [Pa] (hidden) The starting pressure of the volume [Pa] (hidden) |