Fix O2+ charge-exchange temperature exponent in air11 Park mechanism

[MaXXe4th]

Summary

Correct the temperature exponent for the charge-exchange reaction

O2+ + O -> O+ + O2

in air11_Park.xml and 'air11_Park_legacy.xml'.

Park (1993), Table 2, gives:

• A = 4.0E12
• n = -0.09
• Ta = 18000 K

The mechanism currently uses n = +0.09.

The corresponding reaction in Mars_19_Park.xml already uses n = -0.09.

air11_Park_legacy.xml contains the same value and is also changed to provide correct results for legacy users.

[mgoodson-cvd]

Definitely looks like a bug to me. Thanks for the PR!

[capriatim]

Hi @MaXXe4th, thanks for reporting this.

I was checking; there are 2 versions of the same paper (Review of Chemical-Kinetic Problems of Future NASA Missions, I: Earth Entries): one with a positive value, one with a negative value.

I see a negative value reported in other codes, and I agree that the modification would be consistent with the Mars mechanism.

Can you please leave the legacy file unchanged, such that if someone has tests built around the old version of the mechanism can still perform them?

‎Thanks, Michele