A muffler includes a muffler housing having an exhaust gas inlet port adapted for securing to an exhaust pipe of an automobile so that exhaust gases from an internal combustion engine of the automobile are directed through the muffler housing from the exhaust gas inlet to an exhaust gas outlet. The muffler housing includes a plurality of rigid surfaces that form an exhaust gas pathway including a plurality of turns and lead from the exhaust gas inlet port to the exhaust gas outlet port. A photocatalyst coating is secured to an area of the rigid surfaces, and a light source is secured to the muffler housing and positioned to direct light onto the photocatalyst coating. The exhaust gases come into contact with the photocatalyst coating and reactive species generated by the photocatalyst coating decompose one or more pollutants in the exhaust gas.

A muffler includes a muffler housing having an exhaust gas inlet port adapted for securing to an exhaust pipe of an automobile so that exhaust gases from an internal combustion engine of the automobile are directed through the muffler housing from the exhaust gas inlet to an exhaust gas outlet. The muffler housing includes a plurality of rigid surfaces that form an exhaust gas pathway including a plurality of turns and lead from the exhaust gas inlet port to the exhaust gas outlet port. A photocatalyst coating is secured to an area of the rigid surfaces, and a light source is secured to the muffler housing and positioned to direct light onto the photocatalyst coating. The exhaust gases come into contact with the photocatalyst coating and reactive species generated by the photocatalyst coating decompose one or more pollutants in the exhaust gas.

A road vehicle comprising: a passenger compartment; an internal combustion engine; an exhaust system, which releases into the atmosphere the gases generated by the combustion, is connected to the internal combustion engine, and ends with at least one silencer having at least one outlet pipe; and an exhaust noise transmission device, which is provided with a transmission conduit, which originates close to the outlet pipe of the silencer, ends in the area of a wall of the passenger compartment, and is provided, on the inside, with at least one insulating element, which is arranged inside the transmission conduit so as to tightly seal the transmission conduit.

The present application provides a muffler-heat exchanger (15) for an engine exhaust. The muffler-heat exchanger comprises a chamber (16) having an inlet (17) and an outlet (18) arranged such that during use exhaust gases flow through from the inlet to the outlet through the chamber. The muffler-heat exchanger also has at least one heat exchange baffle (25) disposed in the chamber to recover heat energy from the exhaust gases during use. The at least one heat exchange baffle is configured to reflect acoustic waves in the exhaust gases towards the inlet to generate destructive interference and impede incoming acoustic waves at the inlet. The present application also provides an exhaust system and an engine system.

The present application provides a muffler-heat exchanger (15) for an engine exhaust. The muffler-heat exchanger comprises a chamber (16) having an inlet (17) and an outlet (18) arranged such that during use exhaust gases flow through from the inlet to the outlet through the chamber. The muffler-heat exchanger also has at least one heat exchange baffle (25) disposed in the chamber to recover heat energy from the exhaust gases during use. The at least one heat exchange baffle is configured to reflect acoustic waves in the exhaust gases towards the inlet to generate destructive interference and impede incoming acoustic waves at the inlet. The present application also provides an exhaust system and an engine system.

Disclosed herein is a meta-muffler for reducing broadband noise. The meta-muffler includes: a flow pipe through which a fluid flows; an outer barrel disposed outside the flow pipe to be spaced apart from the flow pipe; and multiple metastructures arranged in a flow direction of the fluid and each comprising an opening opened parallel to the flow direction of the fluid, a resonance chamber disposed between the flow pipe and the outer barrel and communicating with the flow pipe through the opening, and a neck adjustment member extending from the outer barrel toward the flow pipe to be spaced apart from the opening in the flow direction of the fluid. The meta-muffler can increase transmission loss of noise flowing through the flow pipe through maximization of energy loss of sound waves entering the resonance chamber of the metastructure and can effectively attenuate noise over a wide band ranging from low frequencies to high frequencies.

The resonator is configured to attenuate the noise in a duct delimiting an internal channel for the flow of a fluid according to a reference axis, of the type including an annular compartment configured to extend around the channel and provided with at least one orifice forming a neck for communication with the flow channel so as to form a resonance chamber. Accordingly, the compartment has an inner structure with a geometry shaped so as to produce a revolution annular asymmetry of the resonance chamber about the reference axis, adapted to generate a phase shift of an acoustic pressure wave reflected inside the chamber relative to an acoustic pressure wave incident from the main flow.

A sound suppressor for use in firearms, internal combustion engines, and numerous other sound-generating devices includes a structure having a plurality of ports, openings, or orifices which function as whistles and which suppress sound from a source of the sound using destructive interference. A combination of varying distances between components is configured for delaying the wave from one port or whistle to the next, so that the whistles are partially out of phase with respect to time, and placing the orifices of the whistles a certain distance apart to compensate for the remaining phase difference in order to create the desired destructive interference.

A muffler including a double-pipe structure to muffle sounds in two or more frequencies is provided. The muffler includes an inner and outer pipes with a clearance therebetween. The inner pipe includes a first and second outer surfaces, and, at one end, an opening communicating with the outer pipe. The clearance communicates with an exhaust passage via the opening. The second outer surface forms the opening and is situated closer to the center of the inner pipe than the first outer surface is. A space between the inner and outer pipes is closed due to a contact between the first outer surface and an inner-circumferential surface of the outer pipe. A part of the clearance is formed between the first outer surface and the inner-circumferential surface. The outer-circumferential surfaces of the inner pipe include at least one communication hole that communicates the inner pipe with the clearance.

The present disclosure provides a gas turbine combustor including a combustion structure (10) having a combustor liner (14) and a flow sleeve (12). The combustor liner (14) includes inner and outer surfaces (31, 30) and defines a combustion zone (15). The gas turbine combustor further includes a plurality of hollow airfoil-shaped structures (22) affixed to the combustor liner (14) and extending radially outwardly into an airflow space (18) defined radially between the flow sleeve (12) and the combustor liner (14). Each hollow structure (22) includes at least one metering tube (26) providing acoustic communication between the combustion zone (15) and the hollow structure (22). The metering tubes (26) are detachably coupled to the combustor liner (14) for permitting interchanging of the metering tube (26) with at least one additional metering tube having at least one different dimension to effect a change in an acoustic characteristic of the hollow structure (22).