Fine Threads since 2008
- Mar 22, 2008
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Right now the model assumes an isentropic acceleration/deceleration of the flow in the inlet, which is fine for subsonic and near sonic flight, but not at all correct for supersonic flight. A normal shock relation (not isentropic) could probably be implemented to do a better job with this. I'll put it on my to-do list. Oblique shocks are a whole other thing and that's heavily geometry dependent, and that simply isn't going to be done in this model. This model, as advertised, should generally act like a jet engine, and in many instances may yield very good agreement with most jet engines, but it simply cannot cover all the details.What do we do about variable geometry inlets, like on the XB-70 or SR-71?
XB-70 has movable ramps to change the inlet area, SR-71 does the same thing with a movable inlet spike.
If you can find me some flight performance data for these engines that would be helpful in validating whatever I can piece together. Right now the best validation of the models I can do is compare sea level stationary thrust values (which I did) and simply note that the engine model trends as expected for real engines at different flight conditions. If you can find me some usable data from supersonic flight conditions for any real jet engine that would be a help.