Modelica.Fluid.Fittings.BaseClasses.GenericResistances.VolumeFlowRate

Information

This package contains utility functions for the VolumeFlowRate fitting component.

Extends from Modelica.Icons.Package (Icon for standard packages).

Package Content

Name	Description
massFlowRate	Return mass flow rate m_flow as function of pressure loss dp for a curved bend
pressureLoss	Return pressure loss dp as function of mass flow rate m_flow for a curved bend

Modelica.Fluid.Fittings.BaseClasses.GenericResistances.VolumeFlowRate.massFlowRate

Information

This function returns the mass flow rate m_flow as function of pressure loss dp for an edged bend. The details of the function are described here.

The bend characteristic is valid for constant density and constant dynamic viscosity. It can be approximately also used for compressible media. This is performed by providing the upstream density and upstream dynamic viscosity. In order to be able to regularize density and dynamic viscosity around zero mass flow rate, the two quantities have to be given if fluid flows from port_a to port_b (d_a, eta_a) and if fluid flows from port_b to port_a (d_b, eta_b).

Inputs

Type	Name	Default	Description
Pressure	dp		Pressure loss [Pa]
Real	a		Coefficient for quadratic term (dp = a*V_flow^2 + b*V_flow) [(Pa.s2)/m6]
Real	b		Coefficient for linear term (dp = a*V_flow^2 + b*V_flow) [(Pa.s)/m3]
Density	d_a		Density at port_a when fluid is flowing from port_a to port_b [kg/m3]
Density	d_b		Density at port_b when fluid is flowing from port_b to port_a [kg/m3]
AbsolutePressure	dp_small		Small pressure drop used for regularization if m_flow=f(...,dp_small,..,dp) [Pa]
MassFlowRate	m_flow_small		Small mass flow rate used for regularization if dp=f_inv(...,m_flow_small,m_flow) [kg/s]

Outputs

Type	Name	Description
MassFlowRate	m_flow	Mass flow rate (= port_a.m_flow) [kg/s]

Modelica definition

function massFlowRate 
  "Return mass flow rate m_flow as function of pressure loss dp for a curved bend"
    import SI = Modelica.SIunits;
  input SI.Pressure dp "Pressure loss";
  input Real a(unit="(Pa.s2)/m6") 
    "Coefficient for quadratic term (dp = a*V_flow^2 + b*V_flow)";
  input Real b(unit="(Pa.s)/m3") 
    "Coefficient for linear term (dp = a*V_flow^2 + b*V_flow)";
  input SI.Density d_a 
    "Density at port_a when fluid is flowing from port_a to port_b";
  input SI.Density d_b 
    "Density at port_b when fluid is flowing from port_b to port_a";
  input SI.AbsolutePressure dp_small 
    "Small pressure drop used for regularization if m_flow=f(...,dp_small,..,dp)";
  input SI.MassFlowRate m_flow_small 
    "Small mass flow rate used for regularization if dp=f_inv(...,m_flow_small,m_flow)";
  output SI.MassFlowRate m_flow "Mass flow rate (= port_a.m_flow)";
algorithm 
   m_flow := Modelica.Fluid.Dissipation.PressureLoss.General.dp_volumeFlowRate_MFLOW(
               Modelica.Fluid.Dissipation.PressureLoss.General.dp_volumeFlowRate_IN_con(
                   a=a,
                   b=b,
                   dp_min=dp_small),
               Modelica.Fluid.Dissipation.PressureLoss.General.dp_volumeFlowRate_IN_var(
                   rho=Modelica.Fluid.Utilities.regStep(dp, d_a, d_b, dp_small)),
               dp);

end massFlowRate;

Modelica.Fluid.Fittings.BaseClasses.GenericResistances.VolumeFlowRate.pressureLoss

Information

This function returns the pressure loss dp as function of mass flow rate m_flow for an edged bend. The details of the function are described here.

The bend characteristic is valid for constant density and constant dynamic viscosity. It can be approximately also used for compressible media. This is performed by providing the upstream density and upstream dynamic viscosity. In order to be able to regularize density and dynamic viscosity around zero mass flow rate, the two quantities have to be given if fluid flows from port_a to port_b (d_a, eta_a) and if fluid flows from port_b to port_a (d_b, eta_b).

Inputs

Type	Name	Default	Description
MassFlowRate	m_flow		Mass flow rate (= port_a.m_flow) [kg/s]
Real	a		Coefficient for quadratic term (dp = a*V_flow^2 + b*V_flow) [(Pa.s2)/m6]
Real	b		Coefficient for linear term (dp = a*V_flow^2 + b*V_flow) [(Pa.s)/m3]
Density	d_a		Density at port_a when fluid is flowing from port_a to port_b [kg/m3]
Density	d_b		Density at port_b when fluid is flowing from port_b to port_a [kg/m3]
AbsolutePressure	dp_small		Small pressure drop used for regularization if m_flow=f(...,dp_small,..,dp) [Pa]
MassFlowRate	m_flow_small		Small mass flow rate used for regularization if dp=f_inv(...,m_flow_small,m_flow) [kg/s]

Outputs

Type	Name	Description
Pressure	dp	Pressure loss [Pa]

Modelica definition

function pressureLoss 
  "Return pressure loss dp as function of mass flow rate m_flow for a curved bend"

    import SI = Modelica.SIunits;
  input SI.MassFlowRate m_flow "Mass flow rate (= port_a.m_flow)";
  input Real a(unit="(Pa.s2)/m6") 
    "Coefficient for quadratic term (dp = a*V_flow^2 + b*V_flow)";
  input Real b(unit="(Pa.s)/m3") 
    "Coefficient for linear term (dp = a*V_flow^2 + b*V_flow)";
  input SI.Density d_a 
    "Density at port_a when fluid is flowing from port_a to port_b";
  input SI.Density d_b 
    "Density at port_b when fluid is flowing from port_b to port_a";
  input SI.AbsolutePressure dp_small 
    "Small pressure drop used for regularization if m_flow=f(...,dp_small,..,dp)";
  input SI.MassFlowRate m_flow_small 
    "Small mass flow rate used for regularization if dp=f_inv(...,m_flow_small,m_flow)";
  output SI.Pressure dp "Pressure loss";
algorithm 
   dp := Modelica.Fluid.Dissipation.PressureLoss.General.dp_volumeFlowRate_DP(
               Modelica.Fluid.Dissipation.PressureLoss.General.dp_volumeFlowRate_IN_con(
                   a=a,
                   b=b,
                   dp_min=dp_small),
               Modelica.Fluid.Dissipation.PressureLoss.General.dp_volumeFlowRate_IN_var(
                   rho=Modelica.Fluid.Utilities.regStep(m_flow, d_a, d_b, m_flow_small)),
               m_flow);

end pressureLoss;