A system for attenuating acoustic energy in machines is provided. The system may include an inner tube disposed about a central axis, an outer tube disposed about the inner tube and the central axis, and a middle tube disposed about the central axis and between the inner tube and the outer tube. The system may also include a first annular ring extending radially from the outer tube and configured to couple the outer tube to the middle tube. The system may further include a second annular ring extending radially from the inner tube and configured to couple the inner tube to the outer tube, such that an acoustic resonator may be formed by the first annular ring, the second annular ring, a portion of the inner tube, a portion of the outer tube, and a portion of the middle tube.

A vascular wall of a combustor that may be for a gas turbine engine includes a first face defining at least in-part a combustion chamber, a second face defining at least in-part a cooling air plenum, and a vascular lattice structure located between the first and second faces for distributing cooling air from the plenum and to the chamber. The vascular lattice structure may be configured to enhance cooling air flow where needed whiling providing structural support. The orientation of the vascular lattice structure may further contribute toward acoustic dampening.

A fireplace system having one or more elements that operate to reduce the energy of acoustic signals propagating through the fireplace system before they are broadcast from a firebox of the fireplace system into a room within which the fireplace system is located. In some examples, a powered exhaust evacuation system is coupled to the fireplace system and an acoustic attenuation element of the fireplace system operates to reduce the acoustic signal of the powered exhaust evacuation system as it propagates through the acoustic attenuation element.

The invention refers to a sequential combustor arrangement including a first burner, a first combustion chamber, a mixer for admixing a dilution gas to the hot gases leaving the first combustion chamber during operation, a second burner, and a second combustion chamber arranged sequentially in a fluid flow connection. The mixer includes a plurality of injection pipes pointing inwards from the side walls of the mixer for admixing the dilution gas to cool the hot flue gases leaving the first combustion chamber with a low pressure drop. The disclosure further refers to a method for operating a gas turbine with such a combustor arrangement.

The invention concerns a gas turbine fuel pipe, having a fuel line, the fuel line having a fuel line volume, a fuel line outer wall and an opening in the fuel line outer wall, a damper having a damper volume and a damper outer wall and attached in fluid communication with the fuel line, wherein the damper covers the opening in the fuel line outer wall, and a perforated lining extending across at least part of the opening in the fuel line outer wall.

The invention refers to a combustor arrangement of a gas turbine engine or power plant, having at least one combustion chamber, at least one mixer for admixing a dilution medium or air to the hot gas flow leaving the combustion chamber. The mixer is configured to guide combustion gases in a hot gas flow path extending downstream of the combustion chamber, wherein the mixer includes a plurality of injection pipes pointing inwards from the side walls of the mixer for admixing the dilution medium or air to cool the hot gas flow leaving combustion chamber. The mixer includes at least one dilution air plenum having at least one pressure-controlled compartment which is directly or indirectly connected to at least one injection pipe.

A sound level reducing apparatus and method for reducing the outdoor sound level produced by a high efficiency gas furnace. The apparatus comprising a muffler having an internal length determined by an identified target pure tone frequency producing an undesirable sound level. The internal length may be optimized to reduce the sound level across a range of operational frequencies.

[Problems to be Solved] An exhaust duct (4) for assembly into a combustion apparatus has: a burner (1) to eject air-fuel mixture downward; and a combustion box (3) disposed on a lower side of the burner (1). The exhaust duct includes: a riser duct section (42) elongated in a vertical direction and having, at a lower portion thereof, an inlet port (41) connected to an exhaust port (35) for combustion gas which is opened in a lower portion of the combustion box (3); and a flat horizontal duct section (43) bent at an upper end of the riser duct section (42) so as to be elongated forward. By restraining the resonance of an upper wall part (431) and a lower wall part (432) of the horizontal duct section (43), noises due to resonance sounds are reduced. [Solving Means] The natural frequencies in an upper wall part (431) and the lower wall part (432) of the horizontal duct section (43) are varied from each other. For example, the lower wall part (432) is fixed to a burner body (11) in order to vary the natural frequencies of the upper wall part (431) and of the lower wall part (432) from each other.

A gas burner system has a gas burner with a conduit through which an air-gas mixture is conducted; a variable-speed forced-air device that forces air through the conduit; a control valve that controls a supply of gas for mixture with the air to thereby form the air-gas mixture; and an electrode configured to ignite the air-gas mixture so as to produce a flame. The electrode is further configured to measure a flame ionization current associated with the flame. A controller is configured to actively control the variable-speed forced-air device based on the flame ionization current measured by the electrode so as to automatically avoid a flame harmonic mode of the gas burner. Corresponding methods are provided.

A combustor including a first perforated layer including a first opening having a first diameter, wherein the first opening is configured to receive a flow of fluid including a fuel and air mixture; and impart a first rotational instability to the flow of fluid that is dependent on the first diameter; and a second perforated layer surrounding a combustion area, wherein the second perforated later includes a second opening having a second diameter, and wherein the second layer is located between the first layer and the combustion area.