Pulse detonation/deflagration apparatus and related methods for enhancing DDT wave production

Pulse detonation/deflagration apparatus for providing enhanced pressure wave operating frequency and/or magnitude, and methods of increasing the frequency or the magnitude of deflagration to detonation waves, are provided. A pulse detonation/deflagration apparatus can include a main/outer pulse detonation/deflagration actuator/engine (PDA/E) with multiple smaller internal combustion chambers or tubes positioned inside the cavity of the main/outer PDA/E with each performing the function of individual PDA/Es. The output pressure waves created by the internal PDA/Es can be utilized for propulsion or for controlling large scale flows, where needed.