added C++ combustor example

Cantera/cxx/demos/combustor.cpp

@@ -0,0 +1,136 @@
+
+// A combustor. Two separate stream - one pure methane and the other
+// air, both at 300 K and 1 atm flow into an adiabatic combustor where
+// they mix. We are interested in the steady-state burning
+// solution. Since at 300 K no reaction will occur between methane and
+// air, we need to use an 'igniter' to initiate the chemistry. A simple
+// igniter is a pulsed flow of atomic hydrogen. After the igniter is
+// turned off, the system approaches the steady burning solution."""
+
+#include <cantera/Cantera.h>
+#include <cantera/zerodim.h>
+#include <cantera/IdealGasMix.h>
+
+void runexample() {
+
+    // use reaction mechanism GRI-Mech 3.0
+    IdealGasMix gas("gri30.cti", "gri30");
+    int nsp = gas.nSpecies();
+
+    // create a reservoir for the fuel inlet, and set to pure methane.
+    Reservoir fuel_in;
+    gas.setState_TPX(300.0, OneAtm, "CH4:1.0");
+    fuel_in.insert(gas);
+    double fuel_mw = gas.meanMolecularWeight();
+
+    // create a reservoir for the air inlet
+    Reservoir air_in;
+    IdealGasMix air("air.cti");
+    gas.setState_TPX(300.0, OneAtm, "N2:0.78, O2:0.21, AR:0.01");
+    double air_mw = air.meanMolecularWeight();
+    air_in.insert(gas);
+
+    // to ignite the fuel/air mixture, we'll introduce a pulse of radicals.
+    // The steady-state behavior is independent of how we do this, so we'll
+    // just use a stream of pure atomic hydrogen.
+    gas.setState_TPX(300.0, OneAtm, "H:1.0");
+    Reservoir igniter;
+    igniter.insert(gas);
+
+
+    // create the combustor, and fill it in initially with N2
+    gas.setState_TPX(300.0, OneAtm, "N2:1.0");
+    Reactor combustor;
+    combustor.insert(gas);
+    combustor.setInitialVolume(1.0);
+
+
+    // create a reservoir for the exhaust. The initial composition
+    // doesn't matter.
+    Reservoir exhaust;
+    exhaust.insert(gas);
+
+
+    // lean combustion, phi = 0.5
+    double equiv_ratio = 0.5;
+
+    // compute fuel and air mass flow rates
+    double factor = 0.1;
+    double air_mdot = factor*9.52*air_mw;
+    double fuel_mdot = factor*equiv_ratio*fuel_mw;
+
+    // create and install the mass flow controllers. Controllers
+    // m1 and m2 provide constant mass flow rates, and m3 provides
+    // a short Gaussian pulse only to ignite the mixture
+    MassFlowController m1;
+    m1.install(fuel_in, combustor);
+    m1.setMassFlowRate(fuel_mdot);
+
+    // Now create the air mass flow controller.  Note that this connects
+    // two reactors with different reaction mechanisms and different
+    // numbers of species. Downstream and upstream species are matched by
+    // name.
+    MassFlowController m2;
+    m2.install(air_in, combustor);
+    m2.setMassFlowRate(air_mdot);
+
+
+    // The igniter will use a Guassiam 'functor' object to specify the
+    // time-dependent igniter mass flow rate.
+    double A = 0.1;
+    double FWHM = 0.2;
+    double t0 = 1.0;
+    Gaussian igniter_mdot(A, t0, FWHM);
+    
+    MassFlowController m3;
+    m3.install(igniter, combustor);
+    m3.setFunction(&igniter_mdot);
+
+    // put a valve on the exhaust line to regulate the pressure
+    Valve v;
+    v.install(combustor, exhaust);
+    double Kv = 1.0;
+    v.setParameters(1, &Kv);
+
+    // the simulation only contains one reactor
+    ReactorNet sim;
+    sim.addReactor(&combustor);
+
+    // take single steps to 6 s, writing the results to a CSV file
+    // for later plotting.
+    double tfinal = 6.0;
+    double tnow = 0.0;
+    double tres;
+    int k;
+
+    ofstream f("combustor_cxx.csv");
+
+    while (tnow < tfinal) {
+        tnow = sim.step(tfinal);
+        tres = combustor.mass()/v.massFlowRate();
+        f << tnow << ", "
+          << combustor.temperature() << ", "
+          << tres << ", ";
+        ThermoPhase& c = combustor.contents();
+        for (k = 0; k < nsp; k++) {
+            f << c.moleFraction(k) << ", ";
+        }
+        f << endl;
+    }
+    f.close();
+}
+
+int main() {
+
+    try {
+        runexample();
+        return 0;
+    }
+    // handle exceptions thrown by Cantera
+    catch (CanteraError) {
+        showErrors(cout);
+        cout << " terminating... " << endl;
+        appdelete();
+        return 1;
+    }
+}