Merge pull request #2002 from ibpsa/issue2001_computeFlowResistance

mwetter · web-flow · commit 2bfbb3b6f387 · 2025-05-15T06:37:40.000-07:00
add option to advanced tab. Change one example to indicate if the cha…
diff --git a/IBPSA/Fluid/FixedResistances/HydraulicDiameter.mo b/IBPSA/Fluid/FixedResistances/HydraulicDiameter.mo
@@ -2,7 +2,8 @@ within IBPSA.Fluid.FixedResistances;
 model HydraulicDiameter "Fixed flow resistance with hydraulic diameter and m_flow as parameter"
   extends IBPSA.Fluid.FixedResistances.PressureDrop(
     final deltaM =  eta_default*dh/4*Modelica.Constants.pi*ReC/m_flow_nominal_pos,
-    final dp_nominal=fac*dpStraightPipe_nominal);
+    final dp_nominal=fac*dpStraightPipe_nominal,
+    final disableComputeFlowResistance_internal=disableComputeFlowResistance);
 
   parameter Modelica.Units.SI.Length dh=sqrt(4*m_flow_nominal/rho_default/
       v_nominal/Modelica.Constants.pi)
@@ -24,6 +25,10 @@ model HydraulicDiameter "Fixed flow resistance with hydraulic diameter and m_flo
   parameter Real fac(min=1) = 2
     "Factor to take into account resistance of bends etc., fac=dp_nominal/dpStraightPipe_nominal";
 
+  parameter Boolean disableComputeFlowResistance=false
+    "=false to disable computation of flow resistance"
+    annotation(Dialog(tab="Advanced"), Evaluate=true);
+
   final parameter Modelica.Units.SI.PressureDifference dpStraightPipe_nominal(
       displayUnit="Pa") =
     Modelica.Fluid.Pipes.BaseClasses.WallFriction.Detailed.pressureLoss_m_flow(
@@ -125,6 +130,13 @@ then the pressure drop is computed as a linear function of the
 mass flow rate.
 </p>
 <p>
+If the parameter <code>disableComputeFlowResistance</code> is set to <code>true</code>,
+then the pressure drop is not computed. This allows to aggregate <code>dp_nominal</code>
+in other components such as in an actuator using its parameter <code>dpFixed_nominal</code>.
+See <a href=\"modelica://IBPSA.Fluid.Actuators.UsersGuide\">IBPSA.Fluid.Actuators.UsersGuide</a>
+for further information on <code>dpFixed_nominal</code>.
+</p>
+<p>
 Setting <code>allowFlowReversal=false</code> can lead to simpler
 equations. However, this should only be set to <code>false</code>
 if one can guarantee that the flow never reverses its direction.
@@ -177,6 +189,11 @@ This leads to simpler equations.
 </html>", revisions="<html>
 <ul>
 <li>
+May 07, 2025, by Fabian Wuelhorst and Michael Wetter:<br/>
+Add option to <code>disableComputeFlowResistance</code>.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2001\">#2001</a>.
+</li>
+<li>
 September 21, 2021, by Michael Wetter:<br/>
 Corrected typo in comments.<br/>
 This is for
diff --git a/IBPSA/Fluid/FixedResistances/PressureDrop.mo b/IBPSA/Fluid/FixedResistances/PressureDrop.mo
@@ -14,7 +14,11 @@ model PressureDrop
         m_flow_nominal_pos / sqrt(dp_nominal_pos) else 0
     "Flow coefficient, k=m_flow/sqrt(dp), with unit=(kg.m)^(1/2)";
 protected
-  final parameter Boolean computeFlowResistance=(dp_nominal_pos > Modelica.Constants.eps)
+  parameter Boolean disableComputeFlowResistance_internal=false
+    "=false to disable computation of flow resistance"
+    annotation(Evaluate=true);
+  final parameter Boolean computeFlowResistance=
+    (dp_nominal_pos > Modelica.Constants.eps) and not disableComputeFlowResistance_internal
     "Flag to enable/disable computation of flow resistance"
    annotation(Evaluate=true);
   final parameter Real coeff=
@@ -125,6 +129,9 @@ then the pressure drop is computed as a linear function of the
 mass flow rate.
 </p>
 <p>
+To disable any pressure drop calculation, set <code>dp_nominal = 0</code>.
+</p>
+<p>
 Setting <code>allowFlowReversal=false</code> can lead to simpler
 equations. However, this should only be set to <code>false</code>
 if one can guarantee that the flow never reverses its direction.
@@ -177,6 +184,11 @@ This leads to simpler equations.
 </html>", revisions="<html>
 <ul>
 <li>
+April 25, 2025, by Fabian Wuelhorst and Michael Wetter:<br/>
+Add option to disable <code>computeFlowResistance</code> for extending classes.<br/>
+See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/2001\">#2001</a>.
+</li>
+<li>
 September 21, 2018, by Michael Wetter:<br/>
 Decrease value of <code>deltaM(min=...)</code> attribute.
 See <a href=\"https://github.com/ibpsa/modelica-ibpsa/issues/1026\">#1026</a>.
diff --git a/IBPSA/Fluid/FixedResistances/Validation/PressureDropsParallel.mo b/IBPSA/Fluid/FixedResistances/Validation/PressureDropsParallel.mo
@@ -3,9 +3,9 @@ model PressureDropsParallel
    "Test with multiple resistances in parallel"
   extends Modelica.Icons.Example;
 
- package Medium = IBPSA.Media.Water "Medium model";
+  package Medium = IBPSA.Media.Water "Medium model";
 
-    Modelica.Blocks.Sources.Ramp P(
+  Modelica.Blocks.Sources.Ramp P(
       duration=1,
       height=20,
       offset=101315) "Signal source"
@@ -22,19 +22,18 @@ model PressureDropsParallel
 
   IBPSA.Fluid.Sources.Boundary_pT sou1(
     redeclare package Medium = Medium,
-    nPorts=2,
+    nPorts=3,
     use_p_in=true,
     T=293.15) "Pressure boundary condition"
     annotation (Placement(transformation(extent={{-60,28},
             {-40,48}})));
 
   IBPSA.Fluid.Sources.Boundary_pT sin1(
     redeclare package Medium = Medium,
-    nPorts=2,
+    nPorts=3,
     p(displayUnit="Pa") = 101325,
     T=283.15) "Pressure boundary condition"
-    annotation (Placement(transformation(extent={{80,28},
-            {60,48}})));
+    annotation (Placement(transformation(extent={{80,30},{60,50}})));
 
   IBPSA.Fluid.FixedResistances.PressureDrop res2(
     redeclare package Medium = Medium,
@@ -52,12 +51,40 @@ model PressureDropsParallel
     message="Inputs differ, check that lossless pipe is correctly implemented.",
       threShold=1E-4)
     "Assert equality of the two mass flow rates"
-    annotation (Placement(transformation(extent={{40,60},{60,80}})));
+    annotation (Placement(transformation(extent={{70,60},{90,80}})));
 
   IBPSA.Fluid.Sensors.MassFlowRate masFlo1(redeclare package Medium = Medium)
     "Mass flow rate sensor" annotation (Placement(transformation(extent={{20,30},
             {40,50}})));
 
+  IBPSA.Fluid.FixedResistances.PressureDrop res3(
+    redeclare package Medium = Medium,
+    m_flow_nominal=5,
+    dp_nominal=10,
+    deltaM=0.3,
+    linearized=false,
+    from_dp=true) "Flow resistance"
+    annotation (Placement(transformation(extent={{-28,-90},{-8,-70}})));
+  IBPSA.Fluid.Sensors.MassFlowRate masFlo3(redeclare package Medium = Medium)
+    "Mass flow rate sensor" annotation (Placement(transformation(extent={{0,-90},
+            {20,-70}})));
+  IBPSA.Utilities.Diagnostics.AssertEquality assEqu1(
+    message="Inputs differ, check that lossless pipe is correctly implemented.",
+    threShold=1E-4)
+    "Assert equality of the two mass flow rates"
+    annotation (Placement(transformation(extent={{70,-40},{90,-20}})));
+  IBPSA.Fluid.FixedResistances.HydraulicDiameter noRes(
+    redeclare package Medium = Medium,
+    m_flow_nominal=5,
+    linearized=false,
+    from_dp=true,
+    length=10,
+    disableComputeFlowResistance=true)
+    "Flow resistance with computeFlowResistance set to false" annotation (
+      Placement(transformation(
+        extent={{-10,-10},{10,10}},
+        rotation=90,
+        origin={-32,-42})));
 equation
   connect(P.y, sou1.p_in) annotation (Line(points={{-71,46},{-62,46}},
                     color={0,0,127}));
@@ -67,33 +94,54 @@ equation
   connect(res1.port_b, masFlo1.port_a)
     annotation (Line(points={{-8,40},{20,40}},color={0,127,255}));
   connect(sou1.ports[1], res1.port_a) annotation (Line(
-      points={{-40,40},{-28,40}},
+      points={{-40,36.6667},{-34,36.6667},{-34,40},{-28,40}},
       color={0,127,255}));
   connect(sou1.ports[2], res2.port_a) annotation (Line(
-      points={{-40,36},{-34,36},{-34,6.10623e-16},{-28,6.10623e-16}},
+      points={{-40,38},{-34,38},{-34,0},{-28,0}},
       color={0,127,255}));
   connect(sin1.ports[1], masFlo1.port_b) annotation (Line(
-      points={{60,40},{40,40}},
+      points={{60,38.6667},{50,38.6667},{50,40},{40,40}},
       color={0,127,255}));
   connect(sin1.ports[2], masFlo2.port_b) annotation (Line(
-      points={{60,36},{52,36},{52,6.10623e-16},{20,6.10623e-16}},
+      points={{60,40},{52,40},{52,0},{20,0}},
       color={0,127,255}));
   connect(masFlo2.m_flow, assEqu.u1) annotation (Line(
-      points={{10,11},{10,76},{38,76}},
+      points={{10,11},{10,20},{46,20},{46,76},{68,76}},
       color={0,0,127}));
   connect(masFlo1.m_flow, assEqu.u2) annotation (Line(
-      points={{30,51},{30,64},{38,64}},
+      points={{30,51},{30,64},{68,64}},
       color={0,0,127}));
 
+  connect(sou1.ports[3], noRes.port_b) annotation (Line(points={{-40,39.3333},{
+          -40,38},{-32,38},{-32,-32}},
+                                   color={0,127,255}));
+  connect(noRes.port_a, res3.port_a) annotation (Line(points={{-32,-52},{-32,-80},
+          {-28,-80}}, color={0,127,255}));
+  connect(res3.port_b, masFlo3.port_a)
+    annotation (Line(points={{-8,-80},{0,-80}}, color={0,127,255}));
+  connect(masFlo3.port_b, sin1.ports[3]) annotation (Line(points={{20,-80},{56,
+          -80},{56,41.3333},{60,41.3333}},
+                                      color={0,127,255}));
+  connect(masFlo2.m_flow, assEqu1.u1) annotation (Line(points={{10,11},{10,20},
+          {46,20},{46,-24},{68,-24}},color={0,0,127}));
+  connect(masFlo3.m_flow, assEqu1.u2)
+    annotation (Line(points={{10,-69},{10,-36},{68,-36}}, color={0,0,127}));
 annotation (experiment(Tolerance=1e-6, StopTime=1.0),
 __Dymola_Commands(file="modelica://IBPSA/Resources/Scripts/Dymola/Fluid/FixedResistances/Validation/PressureDropsParallel.mos" "Simulate and plot"),
     Documentation(info="<html>
 <p>
 This model tests two resistances in parallel.
+The flow path at the bottom of the model also has one additional hydraulic diameter
+model, but it has <code>noRes.disableComputeFlowResistance=true</code>, thereby
+removing the calculation of the flow resistance in that model.
 </p>
 </html>", revisions="<html>
 <ul>
 <li>
+April 25, 2025, by Michael Wetter and Fabian Wuellhorst:<br/>
+Expanded model to include a component with <code>disableComputeFlowResistance=true</code>.
+</li>
+<li>
 July 20, 2007 by Michael Wetter:<br/>
 First implementation.
 </li>
