An acoustic damper includes a low porosity layer section and a housing. The low porosity layer section is formed in a liner of a gas turbine combustor and has an arrangement of elongated generally S-shaped slots formed therein. The housing has a plurality of feed apertures. The housing is coupled to the low porosity layer section thereby defining a cavity such that air outside the housing is configured to flow through the apertures and through the elongated generally S-shaped slots in the low porosity layer section, thereby transforming acoustic energy into thermal energy and aiding in providing an acoustic dampening effect for the gas turbine combustor during operation thereof.

There is provided a muffler structure of a saddle-type vehicle. The muffler structure is disposed at a downstream side of an exhaust pipe extending from an exhaust port of a cylinder head. A pipe is connected to the exhaust pipe and inserted into a muffler main body. The pipe is provided with an expansion chamber having an inner diameter that is larger than an inner diameter of the exhaust pipe. At least a part of the expansion chamber is disposed in the muffler main body, and a plurality of through holes are formed on an outer peripheral surface of the expansion chamber disposed in the muffler main body.

There is provided a muffler structure of a saddle-type vehicle. The muffler structure is disposed at a downstream side of an exhaust pipe extending from an exhaust port of a cylinder head. A pipe is connected to the exhaust pipe and inserted into a muffler main body. The muffler main body includes a cylindrical portion and a reduced diameter portion joined to a downstream side end portion of the cylindrical portion and having a diameter reduced toward the downstream side thereof. The pipe includes a center pipe passing through the cylindrical portion, and a tail pipe disposed in the reduced diameter portion. An expansion chamber is formed by a space in the reduced diameter portion in the vicinity of the tail pipe.

The disclosed inventive concept provides a further achievement in efforts to produce a tunable exhaust sound for a vehicle. The system provides a tunable exhaust system including a tunable resonator and a pair of tunable mufflers. The tunable resonator includes a housing including first, second and third expansion chambers. A pair of bank-by-bank exhaust conduits extends through the housing. At least one of the conduits includes a band of peripheral perforations within the first expansion chamber. The band is formed at an angle relative to the long axis of the conduit on which it is formed. The mufflers include inlet and outlet pipes. At least one of the outlet pipes includes a variable exhaust gas flow assembly. The variable exhaust gas flow assembly includes a vane shaft, an exhaust gas regulating vane attached to the vane shaft, and a vane actuator for regulating the position of the vane shaft.

A muffler, connected to an engine through an exhaust pipe, includes a shell serving as a muffler body, an inlet pipe configured to introduce exhaust gas from the engine into the shell, an outlet pipe configured to discharge the exhaust gas out of the shell, and a cap configured to be attached to a narrowed portion of the inlet pipe and control the direction in which the exhaust gas flows out. The cap is provided with an opening through which the exhaust gas passes and which regulates the direction in which the exhaust gas flows out.

A muffler may include a shell, first and second baffles, an inlet pipe, first and second outlet pipes, and a communication pipe. The first and second baffles cooperate with the shell to define first, second and third chambers. The first inlet pipe may extend through the shell and may provide exhaust gas to at least one of the first and second chambers. Exhaust gas in the first chamber exits the muffler through the first outlet pipe. Exhaust gas in the second chamber exits the muffler through the second outlet pipe. The communication pipe may include first, second and third openings. The first opening is in communication with the first chamber. The second opening is in communication with the second chamber. The third opening is in communication with the third chamber. The first and second chambers may be in communication with the third chamber through the communication pipe.

An air exhausting device includes a muffler internally divided into a plurality of chambers by a separator, an inlet pipe that couples an exhaust pipe of an engine to the muffler, and an outlet pipe that is a path to discharge an exhaust gas inside the muffler to outside air. The muffler is configured of an expansion chamber to which a downstream end of the inlet pipe opens, and a resonator chamber communicated with only the expansion chamber via a plurality of resonator pipes. Any of or both of lengths and thicknesses of the plurality of resonator pipes are different.

A combined exhaust gas noise silencer consisting of a system of hollow elements with a mutual housing comprising a front face of the silencer connected to the supply pipe of exhaust gases, and a rear face of the silencer with an outlet from the rear face of the silencer, where the originalinlet exhaust gas (?.sub.p) carrying a noise wave is divided into at least two flowsan exhaust gas flow (?.sub.z) carrying a shifted noise wave with delayed wave length, and an exhaust gas flow (?.sub.n) carrying a non-shifted noise wave, which are subsequently combined into a common exhaust gas flow (?.sub.s).

An exhaust after-treatment assembly for an engine system is provided. The exhaust after-treatment assembly includes a housing having an inlet port, an outlet port, a catalyst disposed within a cavity defined by the housing, and a muffler assembly disposed within the cavity downstream of the catalyst. The muffler assembly includes one or more baffle plates disposed longitudinally spaced from one another within the housing to define at least a first resonator chamber and a second resonator chamber. Each of the baffle plates defines an openings aligned to one another about a longitudinal axis of the housing. Further, a resonator tube extends through the openings of the baffle plates and includes an inlet, a perforated portion and one or more outlet ports formed in a wall of the resonator tube. The perforated portion and the outlet ports, respectively in fluid communication with the second resonator chamber and the first resonator chamber.

A silencer includes conduit with a downstream end portion configured from a tubular member which includes a conduit discharge port extending through a silencer main body and discharges exhaust gas to the outside therethrough. The tubular member includes a resonance communication hole communicating with a resonance chamber and an upstream side communication hole and a downstream side communication hole communicating with a second chamber. A barrier wall serving as a throttle portion for throttling an exhaust path at an intermediate location of the tubular member is provided in the inside of the tubular member and between the upstream side communication hole and the downstream side communication hole.