Adjustable exhaust nozzle for detonation engines

A rotating detonation engine, comprising:

• an annular combustion chamber configured for the repetitive high frequency combustion of fuel and oxidizer reactants, wherein the annular combustion chamber includes an internal region, an exterior, an inlet and an outlet;
• an adjustable exhaust nozzle coupled to the outlet of the annular combustion chamber and configured to receive exhaust reactants expelled from the annular combustion chamber, the adjustable exhaust nozzle including a plurality of elongated fins arranged in a conical shape and having inner surfaces, outer surfaces, first distal ends, and second distal ends, the plurality of elongated fins being operable to contract toward a closed position and expand toward an open position, wherein the first distal ends of the elongated fins define a circular exhaust nozzle outlet having a first diameter at the closed position and a second diameter at the open position, the first diameter being smaller than the second diameter;
• and
• a nozzle actuator arrangement coupled to the plurality of elongated fins, the nozzle actuator arrangement including one or more fin adjusters coupled to at least one power transmitter, wherein the one or more fin adjusters are configured to adjust the plurality of elongated fins between the closed position and the open position when power is applied to the at least one power transmitter and during operation of the rotating detonation engine.