Aeoronautics

CONDOR – Applications

The computation of the thermodynamic properties of air at high temperatures is important for the reentry of manned spacecraft and missiles into the Earth’s atmosphere and has been intensively studied for 45 years. Below is a comparison of CONDOR results with an important early paper by A.R. Hochstim.

Similar types of computations are done for modeling entry of spacecraft into other planetary atmospheres (e.g., the Galileo probe into Jupiter and the Pioneer Venus probes) and for modeling the impact of a large bolide on Earth at the end of the Cretaceous about 65 million years ago.

Equilibrium Abundances in High Temperature Air (7000 K, 3.675 atm)
Calculated Mole Fractions
Gas Hochstim* CONDOR
O 0.2868 0.2871
N 0.3170 0.3149
N2 0.3878 0.3893
O2 1.822×10-4 1.772×10-4
e- 5.03×10-4 4.80×10-4
NO 7.660×10-3 7.578×10-3
S 0.9999 0.9995

* This is the column labelled “Detailed Solution” in Hochstim’s summary table.

CONDOR also found these mole fractions:

O+ 2.86×10-5
N+ 3.34×10-5
N2+ 1.02×10-5
O2+ 4.32×10-7
NO+ 4.094×10-4

This makes SXi = 0.9999. Note that Hochstim’s mole fraction for electrons ranges between (4.53 – 5.03)×10-4 depending on his ionization energy for NO (9.40 – 9.25 eV).

References

  1. Hochstim 1960. Kinetics, Equilibria and Performance of High Temperature Systems: Proceedings of the First Conference, Western States Section, the Combustion Institute, Los Angeles, California, 2-5 November 1959. (G. S. Bahn and E. E. Zukoski, Eds.) Butterworth, Washington, D. C.