From 7c878f34583d3bb4152ceaedd9b62b7d100215e6 Mon Sep 17 00:00:00 2001
From: Felix MARSOLLIER <fm4b8dfn@dsp1027505>
Date: Wed, 17 Aug 2022 13:38:01 +0200
Subject: [PATCH] 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
---
.../Components/Orifices/SimpleOpeningComp.mo | 27 +++++++++++--------
1 file changed, 16 insertions(+), 11 deletions(-)
diff --git a/FluidDynamics/Components/Orifices/SimpleOpeningComp.mo b/FluidDynamics/Components/Orifices/SimpleOpeningComp.mo
index c1a4273..4ea3662 100644
--- a/FluidDynamics/Components/Orifices/SimpleOpeningComp.mo
+++ b/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;
--
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