I'm working through Sutton's "Rocket Propulsion Elements," (8th Ed.) and it is mostly gibberish. However, I understand a little bit. Anyways, the question is: When using RP-1 as a fuel, your oxidizer shipment contains 15% nitrogen by mistake. What effects would this have on performance, combustion gasses, etc? What would the optimum mix ratio be?
So, for performance, I can only assume that specific impulse would lessen due to unburnt nitrogen conveying heat to the supersonic gas flow in the nozzle. Combustion gasses would ultimately have a concentration of nitrogen, monatomic nitrogen, nitrous oxide and nitric acid, and possibly some nitrogen tetroxide, as well as the typical combustion gasses (I'm bad at chemistry...). For ratios, I am guessing that the optimum of 2.3 or 2.5 would need to be adjusted to be more oxidizer rich due to nitrogen being inert.
Thoughts? Suggestions? Anything?
EDIT: For the mix ratio, I did a simple calculation accounting for the decrease in oxidation efficiency and came up with a new ratio of 2:1 (for frozen equilibrium).
I also should have pointed out that these ratios are: 2.3:1 for frozen equilibrium expansion and 2.5:1 for shifting equilibrium expansion with gas expansion to sea-level pressure.