Sim Ori No States $—$ Simple orifice model for turbulent flow

The Sim Ori No States component describes the turbulent flow through an orifice if no cavitation occurs using a simple textbook model:

$q=A{C}_{d}\sqrt{\frac{2\mathrm{Δp}}{\mathrm{\rho }}}$

Variables used in the above equations

 $q$ Flow rate $\left[\frac{{m}^{3}}{s}\right]$ $A$ Area of the orifice $\left[{m}^{2}\right]$ ${C}_{d}$ Discharge coefficient $\mathrm{\rho }$ Mass density, from FluidProp $\left[\frac{\mathrm{kg}}{{m}^{3}}\right]$ $\mathrm{Δp}$ Pressure drop across orifice $\left[\mathrm{Pa}\right]$

The mass and flow forces are not included.

Note: This model can cause severe numerical problems for the integration routine if the pressure drop $\mathrm{Δp}$ becomes very small.

Related Components

 Name Description Resistance with laminar flow. Resistance with laminar flow and externally commanded conductance. The component, based on the loss coefficient K, describes both flow regimes: laminar for very small Reynolds numbers and turbulent for higher Reynolds numbers (default model). The component describes both flow regimes, using an interpolation polynomial. Orifice component checking for cavitation. Metering Orifice (that is, model Orifice No States with variable diameter). Two orifices in series, one with variable the other with fixed flow area. Same as Orifice No States, but with the equations rearranged to compute $\mathrm{Δp}$ for given q. Differences between basic models are shown by a figure.

Connections

 Name Description Modelica ID ${\mathrm{port}}_{A}$ Layout of port where oil flows into an element ($0<{m}_{\mathrm{flow}}$, ${p}_{B}<{p}_{A}$ means $0<\mathrm{Δp}$) port_A ${\mathrm{port}}_{B}$ Hydraulic port where oil leaves the component (${m}_{\mathrm{flow}}<0$, ${p}_{B}<{p}_{A}$ means $0<\mathrm{Δp}$) port_B $\mathrm{oil}$ oil

Parameters

General Parameters

 Name Default Units Description Modelica ID ${\mathrm{ΔT}}_{\mathrm{system}}$ $0$ $K$ Temperature offset from system temperature dT_system $d$ $0.001$ $m$ Orifice diameter diameter ${C}_{d}$ $0.707$ Max discharge coefficient C_d

Constant Parameters

 Name Default Units Description Modelica ID $\mathrm{orif}$ $1$ Orifice dimension orif $\mathrm{flowcond}$ $3$ Flow condition flowcond $\mathrm{Transition}$ $1$ Transition model Transition reg type $0$ Regularization type regtype reg param $0$ Regularization parameter regparam $\mathrm{cavitation}$ $\mathrm{false}$ Cavitation cavitation $\mathrm{checkvalve}$ $\mathrm{false}$ checkvalve ${k}_{1}$ $0$ Laminar part k1 ${k}_{2}$ $0$ ${k}_{2}=\frac{1}{{C}_{d}^{2}}$ k2 ${\mathrm{\lambda }}_{c}$ $0$ Critical flow number lambdac $\ell$ $0$ $m$ Orifice length; $1<\frac{\ell }{d}$ length ${\Re }_{\mathrm{trans}}$ $0$ Transition Reynolds number Re_trans ${p}_{\mathrm{trans}}$ $0$ $\mathrm{Pa}$ Transition pressure p_trans ${p}_{\mathrm{closed}}$ $0$ $\mathrm{Pa}$ Cracking pressure p_closed ${G}_{\mathrm{leak}}$ $0$ $\frac{{m}^{3}}{s\mathrm{Pa}}$ Leakage conductance G_Leak

Constants

 Name Value Units Description Modelica ID $\mathrm{α\left[k\right]}$ $0.649$ alpha_k