Relief Valve

Relief valve with opening area linearly dependent on pressure difference

 Description The Relief Valve component models a hydraulic relief valve as a sharp-edge orifice with the orifice area dependent on the pressure across the valve. The area varies linearly from ${A}_{\mathrm{closed}}$ to ${A}_{\mathrm{open}}$ as the pressure varies from ${p}_{\mathrm{closed}}$ to ${p}_{\mathrm{open}}$, and remains at the endpoints for pressures outside this range. Based on the orifice area, the pressure vs flow rate relationships are derived by the formulation used in the Orifice component.
 Optional Volumes The boolean parameters Use volume A and Use volume B, when true, add optional volumes ${V}_{A}$  and ${V}_{B}$ to ports A and B, respectively. See Port Volumes for details. If two orfices or valves are connected, enabling a volume at the common port reduces the the stiffness of the system and improves the solvability.

Connections

 Name Description Modelica ID $\mathrm{portA}$ Upstream hydraulic port portA $\mathrm{portB}$ Downstream hydraulic port portB

Parameters

General Parameters

 Name Default Units Description Modelica ID ${C}_{d}$ $\frac{7}{10}$ Flow-discharge coefficient Cd ${\mathrm{\Re }}_{\mathrm{Cr}}$ $12$ Reynolds number at critical flow ReCr ${p}_{\mathrm{closed}}$ $1.9·{10}^{7}$ $\mathrm{Pa}$ Pressure at which valve is fully closed ($A={A}_{\mathrm{closed}}$) pclosed ${p}_{\mathrm{open}}$ $2.05·{10}^{7}$ $\mathrm{Pa}$ Pressure at which valve is fully open (A = A_open) popen ${A}_{\mathrm{open}}$ $1·{10}^{-5}$ ${m}^{2}$ Valve area when fully open Aopen ${A}_{\mathrm{closed}}$ $1·{10}^{-12}$ ${m}^{2}$ Valve area when closed (leakage) Aclosed

Volume Parameters

 Name Default Units Description Modelica ID Use volume A $\mathrm{false}$ When true a hydraulic volume chamber is added to portA useVolumeA ${V}_{A}$ $1·{10}^{-6}$ ${m}^{3}$ Volume of chamber A Va Use volume B $\mathrm{false}$ When true a hydraulic volume chamber is added to portB useVolumeB ${V}_{B}$ $1·{10}^{-6}$ ${m}^{3}$ Volume of chamber B Vb