added combustor example

Cantera/python/examples/reactors/combustor.py

@@ -0,0 +1,83 @@
+""" 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."""
+
+from Cantera import *
+from Cantera.Reactor import *
+from Cantera.Func import *
+
+# use reaction mechanism GRI-Mech 3.0
+gas = GRI30()
+
+# create a reservoir for the fuel inlet, and set to pure methane.
+gas.set(T = 300.0, P = OneAtm, X = 'CH4:1.0')
+fuel_in = Reservoir(gas)
+fuel_mw = gas.meanMolarMass()
+
+# use predefined function Air() for the air inlet
+air = Air()
+air_in = Reservoir(air)
+air_mw = air.meanMolarMass()
+
+# 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.set(T = 300.0, P = OneAtm, X = 'H:1.0')
+igniter = Reservoir(gas)
+
+
+# create the combustor, and fill it in initially with N2
+gas.set(T = 300.0, P = OneAtm, X = 'N2:1.0')
+combustor = Reactor(contents = gas, volume = 1.0)
+
+# create a reservoir for the exhaust
+exhaust = Reservoir(gas)
+
+# lean combustion, phi = 0.5
+equiv_ratio = 0.5
+
+# compute fuel and air mass flow rates
+factor = 0.1
+air_mdot = factor*9.52*air_mw
+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
+m1 = MassFlowController(upstream = fuel_in,
+                        downstream = combustor, mdot = fuel_mdot)
+
+# note that this connects two reactors with different reaction
+# mechanisms and different numbers of species. Downstream and upstream
+# species are matched by name.
+m2 = MassFlowController(upstream = air_in,
+                        downstream = combustor, mdot = air_mdot)
+
+# The igniter will use a Guassiam 'functor' object to specify the
+# time-dependent igniter mass flow rate.
+igniter_mdot = Gaussian(t0 = 1.0, FWHM = 0.2, A = 0.1)
+m3 = MassFlowController(upstream = igniter,
+                        downstream = combustor, mdot = igniter_mdot)
+
+# put a valve on the exhaust line to regulate the pressure
+v = Valve(upstream = combustor, downstream = exhaust, Kv = 1.0)
+
+# the simulation only contains one reactor
+sim = ReactorNet([combustor])
+
+# take single steps to 6 s, writing the results to a CSV file
+# for later plotting.
+tfinal = 6.0
+tnow = 0.0
+f = open('combustor.csv','w')
+while tnow < tfinal:
+    tnow = sim.step(tfinal)
+    tres = combustor.mass()/v.massFlowRate()
+    writeCSV(f, [tnow, combustor.temperature(), tres]
+             +list(combustor.moleFractions()))
+f.close()
+