Originally Posted by
NutLoose
Err from my Aircraft Engine training in the RAF and yes I did Pulse Jets on the course, gawd knows why, ( mind you we did all the piston engine stuff as well, sleeve valves, radials, rotary's, the lot), you need shutters at the front that move, when the fuel lights the shutters close, then when it goes out and the pressure drops they open allowing air in. Hence the pulses...so it actually has moving parts, otherwise it would be a ramjet.
"The second type of pulsejet is known as the valveless pulsejet.[5] Technically the term for this engine is the acoustic-type pulsejet, or aerodynamically valved pulsejet."
I believe these are the ones where the inlet & outlet face the same way.
From Wikipedia.