A pulse combustor system for reducing noise and/or vibration levels. The system includes a pulse combustor including a combustion chamber, an inlet pipe, an exhaust pipe, and a first fuel injector for injecting fuel into the combustion chamber. The pulse combustor has a fundamental oscillation mode and one or more additional oscillation modes. The system includes at least one pressure sensor for measuring a pressure inside the fuel combustor and/or a at least one fluid velocity sensor for measuring fluid velocity at the inlet pipe or at the exhaust pipe. A controller adjusts a rate of fuel supply to the pulse combustor if the measured pressure and/or the measured velocity is above a predetermined threshold value to reduce excitation of the one or more additional oscillation modes.

A pulse combustor system for reducing noise and/or vibration levels. The system includes a pulse combustor including a combustion chamber, an inlet pipe, an exhaust pipe, and a first fuel injector for injecting fuel into the combustion chamber. The pulse combustor has a fundamental oscillation mode and one or more additional oscillation modes. The system includes at least one pressure sensor for measuring a pressure inside the fuel combustor and/or a at least one fluid velocity sensor for measuring fluid velocity at the inlet pipe or at the exhaust pipe. A controller adjusts a rate of fuel supply to the pulse combustor if the measured pressure and/or the measured velocity is above a predetermined threshold value to reduce excitation of the one or more additional oscillation modes.

A method for operating a rotating detonation engine, having a radially outer wall extending along an axis; a radially inner wall extending along the axis, wherein the radially inner wall is positioned within the radially outer wall to define an annular detonation chamber having an inlet and an outlet, wherein the method includes flowing liquid phase fuel along at least one wall of the radially inner wall and the radially outer wall in a direction from the outlet toward the inlet to cool the at least one wall and heat the liquid fuel to provide a heated liquid fuel; flowing the heated liquid fuel to a mixer at the inlet to reduce pressure of the heated liquid fuel, flash vaporize the heated liquid fuel and mix flash vaporized fuel with oxidant to produce a vaporized fuel-oxidant mixture; and detonating the mixture in the annular detonation chamber.

A diffuser may comprise an inlet and an outlet. The inlet may comprise an arcuate shape. The outlet may comprise an annular shape. The diffuser may transition from the arcuate shape at the inlet to the annular shape at the outlet. The diffuser may comprise a radially inner wall and a radially outer wall disposed opposite the radially inner wall. The radially inner wall and the radially outer wall may partially define a duct.

A diffuser may comprise an inlet and an outlet. The inlet may comprise an arcuate shape. The outlet may comprise an annular shape. The diffuser may transition from the arcuate shape at the inlet to the annular shape at the outlet. The diffuser may comprise a radially inner wall and a radially outer wall disposed opposite the radially inner wall. The radially inner wall and the radially outer wall may partially define a duct.

An internal combustion engine wherein a thermo potential heat flow in combustion is maximized by providing a feedback of an optimized amount of thermo potential heat flow that is modulated in the exhaust media, into the air intake, and a method of providing feedback comprises producing a shock wave of pulse of exhaust media and pulse of intake air on the opposite side of a high temperature shock tube thereby transferring the thermo potential heat energy flow from the exhaust media to the air intake.

An internal combustion engine wherein a thermo potential heat flow in combustion is maximized by providing a feedback of an optimized amount of thermo potential heat flow that is modulated in the exhaust media, into the air intake, and a method of providing feedback comprises producing a shock wave of pulse of exhaust media and pulse of intake air on the opposite side of a high temperature shock tube thereby transferring the thermo potential heat energy flow from the exhaust media to the air intake.

A propulsion system defining a longitudinal centerline extended along a longitudinal direction is provided. The propulsion system includes an inlet section configured to provide an oxidizer to a rotating detonation combustion system positioned downstream of the inlet section. The rotating detonation combustion system includes a nozzle assembly positioned to provide a flow mixture of oxidizer and fuel to a combustion chamber, a centerbody forming an inner wall of the combustion chamber, an outer wall at least partially surrounding the centerbody, wherein the inner wall and the outer wall define a volume of the combustion chamber; and an actuation structure coupled to the nozzle assembly. The actuation structure is configured to expand and contract to displace the nozzle assembly along the longitudinal direction to alter the volume of the combustion chamber.

A pulse combustor system for efficiently operating a pulse combustor. The pulse combustor system includes the pulse combustor and a duct. The pulse combustor has a combustion chamber defining an internal space, a conduit having a first end in fluid communication with the internal space and a second end in fluid communication with an environment outside of the pulse combustor system, and a fuel injector configured to inject fuel into the internal space of the combustion chamber. The duct has two openings, with one opening disposed adjacent to the second end of the conduit. The pulse combustor system has an average operating frequency, and the duct has a length that is about one quarter of a wavelength corresponding to the average operating frequency. The pulse combustor and the duct each has a central longitudinal axis, and the two axes are substantially aligned.

A pulse combustor system for efficiently operating a pulse combustor. The pulse combustor system includes the pulse combustor and a duct. The pulse combustor has a combustion chamber defining an internal space, a conduit having a first end in fluid communication with the internal space and a second end in fluid communication with an environment outside of the pulse combustor system, and a fuel injector configured to inject fuel into the internal space of the combustion chamber. The duct has two openings, with one opening disposed adjacent to the second end of the conduit. The pulse combustor system has an average operating frequency, and the duct has a length that is about one quarter of a wavelength corresponding to the average operating frequency. The pulse combustor and the duct each has a central longitudinal axis, and the two axes are substantially aligned.