Enhancement: removal reference to state.X that is not present in all media

Error correction: wrong expression for mass fraction in the mass flow vector at ports

FluidDynamics/Components/Orifices/SimpleOpeningComp.mo

@@ -6,6 +6,9 @@ model SimpleOpeningComp
   // User defined parameters
   parameter Real Cd = 0.61 "discharge coefficient";
   parameter Modelica.SIunits.CrossSection A = 1 "Opening cross section";
+  parameter Modelica.SIunits.Length Alt_a = 1.0 "Altitude of port_a";
+  parameter Modelica.SIunits.Length Alt_b = 1.0 "Altitude of port_b";
+  parameter Modelica.SIunits.Length Alt_opening = 1.0 "Altitude at the opening center";
   
   // Internal variables
   Modelica.SIunits.PressureDifference dp;
@@ -20,7 +23,7 @@ model SimpleOpeningComp
   Modelica.SIunits.IsentropicExponent gamma "isentropic exponent";
   Modelica.SIunits.MachNumber M "Mach number at the orifice";
   Modelica.SIunits.Temperature T "Temperature at the orifice";
-  Medium.ThermodynamicState state "State of upstream flow";
+  Medium.ThermodynamicState state_upstream "State of upstream flow";
   Medium.ThermodynamicState state_a, state_b "States at ports";
   
   // Imported modules
@@ -33,20 +36,21 @@ protected
   Modelica.SIunits.SpecificEnthalpy h_a "Specific enthalpy from port_a" ;
   Modelica.SIunits.SpecificEnthalpy h_b "Specific enthalpy from port_b" ;
   parameter Modelica.SIunits.PressureDifference dp_small = 0.001 ;
+  constant Modelica.SIunits.Acceleration g = Modelica.Constants.g_n;
   
 equation
 //
   state_a = Medium.setState_dTX(d = sum(port_a.d), T = port_a.T, X = port_a.d / sum(port_a.d) );
   state_b = Medium.setState_dTX(d = sum(port_b.d), T = port_b.T, X = port_b.d / sum(port_b.d) );  
-  state = Medium.setSmoothState(
+  state_upstream = Medium.setSmoothState(
     x = dp, 
     x_small = dp_small, 
     state_a = state_a, 
     state_b = state_b);
 
 // pressure reconstruction
-  p_a = Medium.pressure(state_a);
-  p_b = Medium.pressure(state_b);
+  p_a = Medium.pressure(state_a) + sum(port_a.d) * g * (Alt_a - Alt_opening);
+  p_b = Medium.pressure(state_b) + sum(port_b.d) * g * (Alt_b - Alt_opening);
   dp = p_a - p_b;
 
 // specific enthalpy reconstruction
@@ -54,20 +58,21 @@ equation
   h_b = Medium.specificEnthalpy(state_b);
   
 // gamma is supposed contant along the flow
-  gamma = Medium.isentropicExponent(state);
+  gamma = Medium.isentropicExponent(state_upstream);
   
 // Mach number calculation: The pressure at the orifice is the downstream node pressure
   M = min(1, (2 / (gamma - 1) * ((min(p_a, p_b) / max(p_a, p_b)) ^ ((1 - gamma) / gamma) - 1)) ^ 0.5);
   
 // Calculation temperature at the orifice
-  T = Medium.temperature(state) / (1 + (gamma - 1) / 2 * M ^ 2);
+  T = Medium.temperature(state_upstream) / (1 + (gamma - 1) / 2 * M ^ 2);
+
+// Calculation density at the orifice
+  d = Medium.density(state_upstream) / (1 + (gamma - 1) / 2 * M ^ 2) ^ (1 / (1 - gamma));
   
 // solution 1: The velocity is computed from the Mach number and the velocity of sound
-  c = Medium.velocityOfSound(Medium.setState_pTX(p = min(p_a, p_b), T = T, X = state.X));
+  //c = Medium.velocityOfSound(Medium.setState_pTX(p = min(p_a, p_b), T = T, X = state.X));
+  c = sqrt(gamma * min(p_a, p_b) / d);
   Vel = M * c * sign(dp);
-  
-// Calculation density at the orifice
-  d = Medium.density(state) / (1 + (gamma - 1) / 2 * M ^ 2) ^ (1 / (1 - gamma));
   m_flow = Vel * A * Cd * d;
   
 // solution 2: The velocity is computed from the compressible Bernoulli relation
@@ -89,7 +94,7 @@ equation
     x = dp, 
     x_small = dp_small, 
     y1 = port_a.d/sum(port_a.d), 
-    y2 = port_a.d/sum(port_a.d));
+    y2 = port_b.d/sum(port_b.d));
   port_a.m_flow + port_b.m_flow = fill(0.0, Medium.nX);
   port_a.H_flow = semiLinear(m_flow, h_a + g*(Alt_a - Alt_b), h_b - g*(Alt_a - Alt_b) );
   port_a.H_flow + port_b.H_flow = 0;