FIELD

The present subject matter is related to continuous detonation combustion systems for Brayton cycle machines.

BACKGROUND

Propulsion systems, including gas turbines, ramjets, and scramjets, often use deflagrative combustion systems to burn a fuel/oxidizer mixture to produce combustion gases that are expanded and released to produce thrust. While such propulsion systems have reached a high level of thermodynamic efficiency through steady improvements in component efficiencies and increases in pressure ratio and peak temperatures, further improvements are nonetheless welcome in the art.

More particularly, further improvements are desired in stabilization of the combustion process generally. More specifically, further improvements are desired for combustion systems applied in gas turbine augmenter/afterburner or inter-turbine burner systems, ramjets, and scramjets.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

The present disclosure is directed to a Brayton cycle engine and a method for operation. The engine includes a longitudinal wall extended along a lengthwise direction. The longitudinal wall defines a gas flowpath of the engine. An inner wall assembly is extended from the longitudinal wall into the gas flowpath. The inner wall assembly defines a detonation combustion region in the gas flowpath upstream of the inner wall assembly. An actuator configured to adjust a cross sectional area of the gas flowpath adjusts a depth of the detonation combustion region into the gas flowpath. The method for operating the engine includes flowing an oxidizer through a gas flowpath into a combustion section; capturing a portion of the flow of oxidizer via an inner wall extended into a depth of the gas flowpath; flowing a first flow of fuel to the portion of the flow of oxidizer captured via the inner wall; producing a rotating detonation wave of detonation gases via a mixture of the first flow of fuel and the portion of oxidizer upstream of the inner wall; flowing at least a portion of the detonation gases downstream and mixing the detonation gases with the flow of oxidizer; flowing a second flow of fuel to the mixture of detonation gases and the flow of oxidizer; and burning the mixture of the second flow of fuel, the detonation gases, and the flow of oxidizer to produce thrust.

In various embodiments, the method for operating the engine includes adjusting a cross sectional area of the gas flowpath based on an operating condition of the engine. In one embodiment, adjusting the cross sectional area of the gas flowpath includes adjusting one or more of a pressure, flow, or temperature of the first flow of fuel based at least on an operating condition of the engine. In another embodiment, the operating condition of the engine is based at least on a pressure, temperature, or flow rate of the flow of oxidizer at the combustion section. In still various embodiments, adjusting the cross sectional area of the gas flowpath includes adjusting a depth into the gas flowpath of the inner wall based at least on an operating condition of the engine. In one embodiment, adjusting the depth of the inner wall into the gas flowpath is between approximately 0% and approximately 35% of the depth of the gas flowpath. In another embodiment, adjusting the depth of the inner wall into the gas flowpath is further based at least on a desired minimum number of detonation cells to produce the rotating detonation wave.

In one embodiment of the method for operating the engine, burning the mixture of the second flow of fuel, the detonation gases, and the flow of oxidizer to produce thrust includes a deflagrative combustion process.

In another embodiment, the flow of oxidizer at the combustion section defines a supersonic axial velocity through the gas flowpath producing an oblique shockwave from the flow of oxidizer in the gas flowpath.

In various embodiments, the method for operating the engine further includes adjusting a profile of the oblique shockwave based on an operating condition of the engine. In one embodiment, adjusting the profile of the oblique shockwave includes adjusting a depth into the gas flowpath of the inner wall.

In still various embodiments, the actuator is coupled to the inner wall assembly. The actuator adjusts the depth of the inner wall assembly in the gas flowpath. In one embodiment, the actuator extends the inner wall assembly between approximately 0% and approximately 35% of a depth of the gas flowpath. In still other embodiments, the inner wall assembly includes an upstream face extended from the longitudinal wall into the gas flowpath, and a downstream face extended from the longitudinal wall and coupled to the upstream face in the gas flowpath. The downstream face is disposed at an angle relative to the longitudinal wall. In one embodiment, the actuator adjusts the angle of the downstream face relative to the longitudinal wall. In another embodiment, the downstream wall is between approximately 10 degrees and approximately 80 degrees relative to the longitudinal wall. In still another embodiment, the upstream face of the inner wall assembly defines the first fuel injection port providing a first flow of fuel to the detonation combustion region. In still yet another embodiment, the downstream face of the inner wall assembly defines the second fuel injection port providing a second flow of fuel downstream of the detonation combustion region. In various embodiments, the longitudinal wall defines the first fuel injection port providing a first flow of fuel to the detonation combustion region.

These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

