WOLFRAM SYSTEM MODELER
SimpleGenericOrificeSimple generic orifice defined by pressure loss coefficient and diameter (only for flow from port_a to port_b) |
SystemModel["Modelica.Fluid.Fittings.SimpleGenericOrifice"]
This information is part of the Modelica Standard Library maintained by the Modelica Association.
This pressure drop component defines a simple, generic orifice, where the loss factor ζ is provided for one flow direction (e.g., from loss table of a book):
Δp = 0.5*ζ*ρ*v*|v| = 8*ζ/(π^2*D^4*ρ) * m_flow*|m_flow|
where
Since the pressure loss factor zeta is provided only for a mass flow from port_a to port_b, the pressure loss is not correct when the flow is reversing. If reversing flow only occurs in a short time interval, this is most likely uncritical. If significant reversing flow can appear, this component should not be used.
dp_start |
Value: dp_nominal Type: AbsolutePressure (Pa) Description: Guess value of dp = port_a.p - port_b.p |
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m_flow_small |
Value: if system.use_eps_Re then system.eps_m_flow * m_flow_nominal else system.m_flow_small Type: MassFlowRate (kg/s) Description: Small mass flow rate for regularization of zero flow |
show_T |
Value: true Type: Boolean Description: = true, if temperatures at port_a and port_b are computed |
show_V_flow |
Value: true Type: Boolean Description: = true, if volume flow rate at inflowing port is computed |
allowFlowReversal |
Value: system.allowFlowReversal Type: Boolean Description: = true to allow flow reversal, false restricts to design direction (m_flow >= 0) |
momentumDynamics |
Value: Types.Dynamics.SteadyState Type: Dynamics Description: Formulation of momentum balance |
m_flow_start |
Value: system.m_flow_start Type: MassFlowRate (kg/s) Description: Start value of mass flow rates |
diameter |
Value: Type: Diameter (m) Description: Diameter of orifice |
zeta |
Value: Type: Real Description: Loss factor for flow of port_a -> port_b |
use_zeta |
Value: true Type: Boolean Description: = false to obtain zeta from dp_nominal and m_flow_nominal |
m_flow_nominal |
Value: if system.use_eps_Re then system.m_flow_nominal else 1e2 * system.m_flow_small Type: MassFlowRate (kg/s) Description: Mass flow rate for dp_nominal |
dp_nominal |
Value: if not system.use_eps_Re then 1e3 else BaseClasses.lossConstant_D_zeta(diameter, zeta) / Medium.density_pTX(Medium.p_default, Medium.T_default, Medium.X_default) * m_flow_nominal ^ 2 Type: Pressure (Pa) Description: Nominal pressure drop |
use_Re |
Value: system.use_eps_Re Type: Boolean Description: = true, if turbulent region is defined by Re, otherwise by m_flow_small |
from_dp |
Value: true Type: Boolean Description: = true, use m_flow = f(dp) else dp = f(m_flow) |
pathLength |
Default Value: 0 Type: Length (m) Description: Length flow path |
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port_a |
Type: FluidPort_a Description: Fluid connector a (positive design flow direction is from port_a to port_b) |
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port_b |
Type: FluidPort_b Description: Fluid connector b (positive design flow direction is from port_a to port_b) |
state_a |
Type: ThermodynamicState Description: State for medium inflowing through port_a |
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state_b |
Type: ThermodynamicState Description: State for medium inflowing through port_b |
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system |
Type: System Description: System properties |
Modelica.Fluid.Examples Demonstrates the parameterization of a pump and a pipe for given nominal values |