Let's say we are testing a jet engine on the ground by keeping it still. We measure the inlet and outlet velocity of the gas at a specific operation point. Let's assume that we attach this engine on a aircraft that is of course moving. In a random time the operation point is the same as before. If we measure the absolute inlet and outlet velocities are the same as before or only the relative ones(aircraft velocity+gas velocity) are the same?
And one more similar question. In the case of the engine attached to the aircraft all the fuel energy that can be used is transformed into changes of the kinetic energy of both the aircraft and the air passing through the engine.Right? In the first case of the test, the kinetic energy of the engine isn't changing, so all the used fuel energy is changing the gas kinetic energy, so in this case the difference in the kinetic energy of the gas is greater. Does this makes sense since we talk for the same operation point?
To conclude, is the thrust the same regardless if the jet engine is moving or not?