.. DO NOT EDIT. .. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY. .. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE: .. "examples/shock_tube/incidentshock.py" .. LINE NUMBERS ARE GIVEN BELOW. .. only:: html .. note:: :class: sphx-glr-download-link-note :ref:`Go to the end ` to download the full example code. .. rst-class:: sphx-glr-example-title .. _sphx_glr_examples_shock_tube_incidentshock.py: .. _ref_incident_shock_reactor: ============================================================== Nitric oxide formation in air heated by an incident shock wave ============================================================== Shock tube experiments are commonly used to study reaction paths and to measure reaction rates at elevated temperatures. You can apply the incident shock reactor model ``IncidentShock()`` to validate the reaction mechanism or kinetic parameters derived from such experiments. The shock tube reactor models, such as the IncidentShcok, the ReflectedShock and the ZNDCalculator models, are initiated by a stream, which is simply a mixture with the addition of the shock wave velocity. You already know how to create a stream if you know how to create a mixture. You can specify the shock wave velocity using the combination of the ``velocity`` method of the initial gas stream and the ``location`` parameter when you instantiate the ``incidentShock`` or the ``ReflectedShock`` object. This example aims to reproduce one of the shock tube experiments done by Camac and Feinberg. Camac and Feinberg measured the production rates of nitric oxide (NO) in shock-heated air over the temperature range of 2300 [K] to 6000 [K]. The NO mole fraction behind the incident shock will be plotted as a function of time (after the passing of the incident shock front). The NO mole fraction profile rapidly rises to a peak value then gradually falls back to its equilibrium level. The predicted peak NO mole fraction is 0.04609 and is in good agreement with the measured and the computed data by Camac and Feinberg. Reference: M. Camac and R.M. Feinberg, Proceedings of Combustion Institute, vol. 11, p. 137-145 (1967) .. GENERATED FROM PYTHON SOURCE LINES 55-57 .. code-block:: Python :dedent: 1 .. GENERATED FROM PYTHON SOURCE LINES 59-61 Import PyChemkin packages and start the logger ============================================== .. GENERATED FROM PYTHON SOURCE LINES 61-83 .. code-block:: Python from pathlib import Path import time import ansys.chemkin.core as ck # Chemkin from ansys.chemkin.core import Color # chemkin plug flow reactor model from ansys.chemkin.core.shock.shocktubereactors import IncidentShock from ansys.chemkin.core.inlet import Stream from ansys.chemkin.core.logger import logger import matplotlib.pyplot as plt # plotting # check working directory current_dir = str(Path.cwd()) logger.debug("working directory: " + current_dir) # set interactive mode for plotting the results # interactive = True: display plot # interactive = False: save plot as a PNG file global interactive interactive = True .. GENERATED FROM PYTHON SOURCE LINES 84-90 Create the hot air dissociation mechanism file ============================================== Create a new mechanism input file 'no_hot_air_chem.inp' that contains the reactions to describe NO formation in heated air. This file is saved to the working directory ``current_dir``. .. GENERATED FROM PYTHON SOURCE LINES 90-119 .. code-block:: Python mymechfile = Path(current_dir) / "no_hot_air_chem.inp" m = mymechfile.open(mode="w") # the mechanism contains only the necessary species # (oxygen, nitrogen, nitric oxide, and major byproducts) # declare elements m.write("ELEMENT O N AR END\n") # declare species m.write("SPECIES\n") m.write("O2 N2 NO N O AR\n") m.write("END\n") # write reactions for N2O dissociation # Reference: # M. Camac and R.M. Feinberg, Proceedings of Combustion Institute, # vol. 11, pp. 137-145 (1967) m.write("REACTIONS\n") m.write("N2+O2=NO+NO 9.1E24 -2.5 128500.\n") m.write("N2+O=NO+N 7.0E13 0. 75000.\n") m.write("O2+N=NO+O 1.34E10 1.0 7080.\n") m.write("O2+M=O+O+M 3.62E18 -1.0 118000.\n") m.write("N2/2/ O2/9/ O/25/\n") m.write("N2+M=N+N+M 1.92E17 -0.5 224900.\n") m.write("N2/2.5/ N/0/\n") m.write("N2+N=N+N+N 4.1E22 -1.5 224900.\n") m.write("NO+M=N+O+M 4.0E20 -1.5 150000.\n") m.write("NO/20/ O/20/ N/20/\n") m.write("END\n") # close the mechnaism file m.close() .. GENERATED FROM PYTHON SOURCE LINES 120-126 Create a chemistry set ====================== The mechanism used here is the air dissociation mechanism. The mechanism will be created in situ in the working directory. The thermodynamic data file is the standard one that comes with the Ansys Chemkin installation in the ``/reaction/data`` directory. .. GENERATED FROM PYTHON SOURCE LINES 126-137 .. code-block:: Python # set mechanism directory (the default Chemkin mechanism data directory) data_dir = Path(ck.ansys_dir) / "reaction" / "data" mechanism_dir = data_dir # create a chemistry set based on the N2O dissociation mechanism MyGasMech = ck.Chemistry(label="NO_from_hot_air") # set mechanism input files # including the full file path is recommended MyGasMech.chemfile = str(mymechfile) MyGasMech.thermfile = str(data_dir / "therm.dat") .. GENERATED FROM PYTHON SOURCE LINES 138-140 Preprocess the hydrogen chemistry set ===================================== .. GENERATED FROM PYTHON SOURCE LINES 140-144 .. code-block:: Python # preprocess the mechanism files ierror = MyGasMech.preprocess() .. GENERATED FROM PYTHON SOURCE LINES 145-149 Instantiate and set up the stream ================================= Create a diluted air stream by assigning the mole fractions of the species. .. GENERATED FROM PYTHON SOURCE LINES 149-158 .. code-block:: Python diluted_air = Stream(MyGasMech) # initial gas state before the incident shock front # 5 [torrs] diluted_air.pressure = 5.0 * ck.P_TORRS # 296 [K] diluted_air.temperature = 296.0 # AR diluted air based on the experiment setup diluted_air.x = [("AR", 0.0093), ("O2", 0.2095), ("N2", 0.7812)] # .. GENERATED FROM PYTHON SOURCE LINES 159-172 Create the shock tube reactor object ==================================== Use the ``IncidentShock()`` method to create an incident shock reactor. The ``IncidentShock()`` method has two required input parameters. The first parameter is the "stream" representing the state of the initial gas mixture. In this case, it is the ``diluted_air``. The second required parameter is the location of the initial gas stream relative to the incident shock front. A value of '1' indicate the initial gas stream is before the incident shock front (state 1), and a value of '2' indicates the gas stream is behind the incident shock (state 2). The gas velocity (same as the incident shock velocity) must be given by the ``velocity`` method for ``IncidentShock()`` model. .. GENERATED FROM PYTHON SOURCE LINES 172-180 .. code-block:: Python # set the incident shock velocity [cm/sec] diluted_air.velocity = 2.8e5 # instantiate the shock tube reactor # the location '1' means the gas stream is before the incident shock front Incident = IncidentShock(diluted_air, location=1, label="incident_shock") .. GENERATED FROM PYTHON SOURCE LINES 181-191 Set up additional reactor model parameters ========================================== For the incident shock model, the required reactor parameters is the total simulation time [sec]. The initial gas mixture conditions are defined by the stream when the ``IncidentShock`` is instantiated. To include the boundary layer correction in the shock tube model, you must specify both the 'shock tube diameter' and the 'gas viscosity' at 300 [k] using the ``diameter`` and the ``set_inlet_viscosity()`` methods, respectively. .. GENERATED FROM PYTHON SOURCE LINES 191-201 .. code-block:: Python # to use the boundary layer correction, both diameter and viscocity must be given # shock tube diameter [cm] Incident.diameter = 3.81 # mixture viscosity [g/cm-sec] at 300 [K] Incident.set_inlet_viscosity(2.0e-4) # set total simulation time (particle time) [sec] Incident.time = 2.0e-3 .. GENERATED FROM PYTHON SOURCE LINES 202-206 Set solver controls =================== You can overwrite the default solver controls by using solver related methods, for example, ``tolerances``. .. GENERATED FROM PYTHON SOURCE LINES 206-210 .. code-block:: Python # tolerances are given in tuple: (absolute tolerance, relative tolerance) Incident.tolerances = (1.0e-8, 1.0e-4) .. GENERATED FROM PYTHON SOURCE LINES 211-219 Run the ZND analysis ==================================================== Use the ``run()`` method to start the ZND analysis. .. note :: You can use two ``time`` calls (one before the run and one after the run) to get the simulation run time (wall time). .. GENERATED FROM PYTHON SOURCE LINES 219-235 .. code-block:: Python # set the start wall time start_time = time.time() # run the ZND model runstatus = Incident.run() # compute the total runtime runtime = time.time() - start_time # check run status if runstatus != 0: # Run failed. print(Color.RED + ">>> Run failed. <<<", end=Color.END) exit() # run succeeded. print(Color.GREEN + ">>> Run completed. <<<", end=Color.END) print(f"Total simulation duration: {runtime * 1.0e3} [msec]") .. GENERATED FROM PYTHON SOURCE LINES 236-254 Postprocess the solution ======================== The postprocessing step parses the solution and packages the solution values at each time point into a mixture. There are two ways to access the solution profiles: - The raw solution profiles (value as a function of time) are available for distance, temperature, pressure, velocity, density, and species mass fractions. - The mixtures permit the use of all property and rate utilities to extract information such as viscosity, density, total thermicity, speed of sound, Mach number, and mole fractions. You can use the ``get_solution_variable_profile()`` method to get the raw solution profiles. You can get solution mixtures using either the ``get_solution_stream_at_index()`` method for the solution mixture at the given saved location or the ``get_solution_stream()`` method for the solution mixture at the given distance. (In this case, the mixture is constructed by interpolation.) .. GENERATED FROM PYTHON SOURCE LINES 254-281 .. code-block:: Python # postprocess the solution profiles Incident.process_solution() # get the number of solution time points solutionpoints = Incident.get_solution_size() print(f"number of solution points = {solutionpoints}") # get the time profile [sec] timeprofile = Incident.get_solution_variable_profile("time") # convert to [msec] timeprofile *= 1.0e3 # get the temperature profile [K] tempprofile = Incident.get_solution_variable_profile("temperature") # get the velocity profile [cm/sec] velprofile = Incident.get_solution_variable_profile("velocity") # convert to [m/sec] velprofile *= 1.0e-2 # get the NO mass fraction profile [-] no_profile = Incident.get_solution_variable_profile("NO") # get the O mass fraction profile [-] o_profile = Incident.get_solution_variable_profile("O") # clean up if mymechfile.exists and mymechfile.is_file(): mymechfile.unlink() .. GENERATED FROM PYTHON SOURCE LINES 282-287 Plot the solution profiles ========================== Plot the temperature, the velocity, and the NO and the O species mass fraction profiles as a function of time. .. GENERATED FROM PYTHON SOURCE LINES 287-313 .. code-block:: Python plt.subplots(2, 2, sharex="col", figsize=(12, 6)) plt.suptitle("Incident Shock", fontsize=16) plt.subplot(221) plt.plot(timeprofile, tempprofile, "r-") plt.ylabel("Temperature [K]") plt.subplot(222) plt.plot(timeprofile, velprofile, "b-") plt.ylabel("Velocity [m/sec]") plt.subplot(223) plt.plot(timeprofile, no_profile, "g-") plt.xlabel("time [msec]") plt.ylabel("NO Mass Fraction [-]") plt.subplot(224) plt.plot(timeprofile, o_profile, "m-") plt.xlabel("time [msec]") plt.ylabel("O Mass Fraction [-]") # clean up ck.done() # plot results if interactive: plt.show() else: plt.savefig("plot_incident_shock.png", bbox_inches="tight") .. _sphx_glr_download_examples_shock_tube_incidentshock.py: .. only:: html .. container:: sphx-glr-footer sphx-glr-footer-example .. container:: sphx-glr-download sphx-glr-download-jupyter :download:`Download Jupyter notebook: incidentshock.ipynb ` .. container:: sphx-glr-download sphx-glr-download-python :download:`Download Python source code: incidentshock.py ` .. container:: sphx-glr-download sphx-glr-download-zip :download:`Download zipped: incidentshock.zip ` .. only:: html .. rst-class:: sphx-glr-signature `Gallery generated by Sphinx-Gallery `_