How, if at all, does the pressure of the combusting fluid change within a combustion chamber from the injector to the choke? Is it monotonically decreasing in pressure as you go from the injector to the nozzle (which makes sense, given that the fluid is clearly flowing that way)?
Even if so, how uniform is the pressure within the chamber, provided it's properly baffled & there's no combustion instabilities to consider? Is it sufficiently uniform to consider that the fluid is at constant pressure during the entire combustion?