serverlan wrote:Hi Ed,
I can offer just one piece of info.
The colour of the flame indicates its temperature.
I can't remember the exact figure now, but lets say its about 2100K
If the intake temperature is 300K, then the combustion raises the temperature by a factore of 7:1.
If it burns fast enough to achieve this temperature before the pressure disperses, we could expect a similar increase in pressure above atmospheric.
Thus the initial burn pressure could be up to 700000 whatever-the-metric-units-are.
If the gas were to expand as it is burning (i.e. a slower burn) then that temperature would not be reached (expansion produces cooling) and the temperature would be lower and the colour different. So, at the moment I think that is a reasonable pressure estimate. Most people tell me I'm dreaming, that the measured pressure peaks are much less than that.
700,000 whatevers would be 700,000 Pascals or 700,000 Pa. Or in friendlier terms, 7 atmospheres. Except, no Pjet engine gets the full charge to that temperature. Published figures for the Argus only show a total cycle fluction of around two atmospheres, and part of that is in the negative inflow region (below 1 atmosphere).
Pulse detonation, on the other hand, gets local shock temperatures that are to the moon, but those aren't the same as average temps.