Typically, there are annular ports on the injector plate to introduce fuel to cool the combustion chamber. Why is LOx not used for cooling despite it being extremely cold?

Given there will be a lot of LOx droplets on the inside, will it also impinge and provide additional cooling or the combustion chamber design takes care none of the LOx droplet come in contact with the chamber wall?

Cons of cryogenic LOx are:

  • might cause thermal shocks on the wall
  • oxidation/corrosion of chamber wall

This might end up damaging the chamber.

  • $\begingroup$ Fuel may protect the combustion chamber against oxidation, but LOX does not. Especially when curtain or film cooling is used, see Wikipedia. The specific heat energy needed to evaporate the cooling liquid is more important than a very low temperature. $\endgroup$ – Uwe Aug 25 '18 at 12:38
  • $\begingroup$ @Uwe will the injector design ensure no droplets of LOx impinge on the wall during hot firing? $\endgroup$ – karthikeyan Aug 25 '18 at 12:45
  • $\begingroup$ Reaction Engines have tested both an oxidiser film (atmospheric air) cooled combustion chamber, and an oxidiser (LOX) cooled combustion chamber; it's how they intend to cool their SABRE engines. $\endgroup$ – JCRM Aug 26 '18 at 11:29
  • $\begingroup$ @JCRM But LOx might damage the chamber wall which is of different material compared to the nozzle $\endgroup$ – karthikeyan Aug 26 '18 at 11:30

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