NASA CEA Tutorial

# NASA CEA Tutorial

## NASA CEA Tutorial

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##### Presentation Transcript

1. NASA CEA Tutorial Problem Types Rocket Examples References Timothée Pourpoint 1

2. Online Access & Documentation • CEA: • calculates chemical equilibrium product concentrations • determines thermodynamic & transport properties • 2 supporting documents: • Detailed analyses of chemical equilibrium calculations • User manual and program description Request a download http://www.grc.nasa.gov/WWW/CEAWeb/ceaWhat.htm 2/15

4. Problem Types (1/2) • Assigned Temperature and Pressure – tp Chemical equilibrium composition and properties will be calculated for selected temperatures and pressures. • Combustion (Enthalpy and Pressure) – hp Enthalpy held constant resulting in an adiabatic flame temperature, equilibrium mixture properties and composition. • Assigned temperatures and volumes – tv Chemical equilibrium composition and properties are calculated for assigned temperatures and a set of either assigned specific volumes or densities. • Combustion (Internal energy and volumes) – uv Chemical equilibrium composition and properties are calculated for assigned internal energies and assigned total reactant specific volumes or densities. • Rocket – rkt Theoretical rocket performance parameters can be calculated for: • infinite-area or finite-area combustors • chemical equilibrium for all points or freeze composition after combustion, throat, or any exit point. • thermal transport properties 4/15

5. Problem Types (2/2) • Shock tube – shock Calculates shock properties in terms of assigned velocities. • Chapman-Jouquet detonation – det Chapman-Jouguet detonation properties are calculated for a set of unburned gaseous reactants at assigned temperatures and pressures. • Assigned entropy and pressures – sp Converges on both the gaseous and condensed products for a reactant mixture with an assigned entropy and set of pressures. • Assigned entropy and either specific volumes or densities – sv Chemical equilibrium composition and properties calculated for assigned entropy and each assigned total reactant specific volume or density. 5/15

6. Rocket Problems • INFINITE-AREA COMBUSTOR • All points are isentropic with respect to the combustion point. • Can assume chemical equilibrium or products frozen after a specified point. • Freeze points selections are combustion, throat, or exit1. • FINITE-AREA COMBUSTOR • In this chamber combustion is a non-isentropic, irreversible process. • During the burning process, part of the energy released is used to raise the entropy, and the pressure drops. • Expansion in the nozzle is assumed to be isentropic. • Can only assume chemical equilibrium. 6/15

7. Example • Continue with our example from class: • Oxidizer: O2(l) • Fuel: CH4(l) • Pc = 1000 psi • O/F = 4.0 (near stoichiometric) • Ac/At = 3.0 • Ae/At = 10.0, 25.0, 50.0 7/15

8. Inputs to Example (1/4) Problem Tab Click • Notes: • Make sure all inputs are validated by clicking outside of input cells • Make sure there is no space before an input 8/15

9. Inputs to Example (2/4) Reactant Tab Reactant Selector • Notes: • Propellants can be in gaseous, condensed (solid/liquid), or atomic form • Use the search function to quickly find desired propellant 9/15

10. Inputs to Example (3/4) Output Tab • Thermal transport properties are very useful for calculations related to cooling requirements in chamber or at nozzle throat. • Parameters typically used in Bartz equation (Ref. 3): • Output properties from CEA include: • Viscosity [millipoise] • Specific heat, [kJ/kg-K] • Thermal conductivity, [mW/cm-K] • Prandtl number 10/15

11. Inputs to Example (4/4) RUN CEA2 • Save input file (File, Save) • View input file • Click on “Activity” • Click on “View Current INPUT file Ctrl+I” 11/15

12. Output from Example (1/3) Equilibrium Frozen 12/15

13. Output from Example (2/3) Equilibrium Frozen 13/15

14. Output from Example (3/3) Equilibrium Frozen 14/15

15. References • Computer Program for Calculation of Complex Chemical Equilibrium Compositions and Applications I. Analysis, Sanford Gordon and Bonnie J. McBride, National Aeronautics and Space Administration - Lewis Research Center, NASA RP-1311 • Computer Program for Calculation of Complex Chemical Equilibrium Compositions and Applications II. User's Manual and Program Description, Bonnie J. McBride and Sanford Gordon, National Aeronautics and Space Administration - Lewis Research Center, NASA RP-1311-P2 • Modern Engineering for Design of Liquid-Propellant Rocket Engines, Dieter K. Huzel and David H. Huang, Progress in Astronautics and Aeronautics, Volume 147, AIAA 15/15