Modelica.Fluid.Fittings.Orifices

Information

Package Content

Name	Description
ThickEdgedOrifice	Thicked edged orifice flow model

Modelica.Fluid.Fittings.Orifices.ThickEdgedOrifice

Information

This component models a thick edged orifice with sharp corners in the overall flow regime for incompressible and single-phase fluid flow through an arbitrary shaped cross sectional area (square, circular, etc.) considering influence of surface roughness. It is expected that also compressible fluid flow can be handled up to about Ma = 0.3. It is assumed that neither mass nor energy is stored in this component. In the model basically a function is called to compute the mass flow rate as a function of pressure loss for a thick edged orifice. Also the inverse of this function is defined, and a tool might use this inverse function instead, in order to avoid the solution of a nonlinear equation.

The details of the model are described in the documentation of the underlying function.

Extends from Modelica.Fluid.Dissipation.Utilities.Icons.PressureLoss.Orifice_i (Icon for orifice), Modelica.Fluid.Interfaces.PartialPressureLoss (Base flow model for pressure loss functions with the same area at port_a and at port_b).

Parameters

Type	Name	Default	Description
replaceable package Medium		PartialMedium	Medium in the component
Geometry	geometry		Geometry of thick edged orifice
Assumptions
Boolean	allowFlowReversal	system.allowFlowReversal	= true to allow flow reversal, false restricts to design direction (port_a -> port_b)
Advanced
AbsolutePressure	dp_start	0.01*system.p_start	Guess value of dp = port_a.p - port_b.p [Pa]
MassFlowRate	m_flow_start	system.m_flow_start	Guess value of m_flow = port_a.m_flow [kg/s]
MassFlowRate	m_flow_small	system.m_flow_small	Small mass flow rate for regularization of zero flow [kg/s]
Diagnostics
Boolean	show_T	true	= true, if temperatures at port_a and port_b are computed
Boolean	show_V_flow	true	= true, if volume flow rate at inflowing port is computed

Connectors

Type	Name	Description
FluidPort_a	port_a	Fluid connector a (positive design flow direction is from port_a to port_b)
FluidPort_b	port_b	Fluid connector b (positive design flow direction is from port_a to port_b)

Modelica definition

model ThickEdgedOrifice "Thicked edged orifice flow model"
  extends Modelica.Fluid.Dissipation.Utilities.Icons.PressureLoss.Orifice_i;
  extends Modelica.Fluid.Interfaces.PartialPressureLoss;

  parameter Modelica.Fluid.Fittings.BaseClasses.Orifices.ThickEdgedOrifice.Geometry
                                                                            geometry 
    "Geometry of thick edged orifice";

protected 
  parameter Medium.AbsolutePressure dp_small=
             Modelica.Fluid.Dissipation.PressureLoss.Orifice.dp_thickEdgedOverall_DP(
             Modelica.Fluid.Dissipation.PressureLoss.Orifice.dp_thickEdgedOverall_IN_con(
                   A_0=geometry.venaCrossArea,
                   A_1=geometry.crossArea,
                   C_0=geometry.venaPerimeter,
                   C_1=geometry.perimeter,
                   L=geometry.venaLength,
                   dp_smooth=1e-10),
                Modelica.Fluid.Dissipation.PressureLoss.Orifice.dp_thickEdgedOverall_IN_var(
                  rho=Medium.density(state_dp_small),
                  eta=Medium.dynamicViscosity(state_dp_small)),
                m_flow_small) 
    "Default small pressure drop for regularization of laminar and zero flow (calculated from m_flow_small)";
equation 
  if allowFlowReversal then
     m_flow = Modelica.Fluid.Fittings.BaseClasses.Orifices.ThickEdgedOrifice.massFlowRate(
                dp, geometry, d_a, d_b, eta_a, eta_b, dp_small, m_flow_small);
  else
     m_flow = Modelica.Fluid.Dissipation.PressureLoss.Orifice.dp_thickEdgedOverall_MFLOW(
                 Modelica.Fluid.Dissipation.PressureLoss.Orifice.dp_thickEdgedOverall_IN_con(
                   A_0=geometry.venaCrossArea,
                   A_1=geometry.crossArea,
                   C_0=geometry.venaPerimeter,
                   C_1=geometry.perimeter,
                   L=geometry.venaLength,
                   dp_smooth=dp_small),
                Modelica.Fluid.Dissipation.PressureLoss.Orifice.dp_thickEdgedOverall_IN_var(rho=d_a, eta=eta_a), dp);
  end if;

end ThickEdgedOrifice;