An exhaust duct assembly for conveying exhaust gases emanating from a combustion zone to atmosphere is disclosed. The assembly includes: an exhaust gas outlet for exhausting exhaust gas into the atmosphere; and an acoustic duct portion located upstream of the exhaust gas outlet, the acoustic duct portion having a peripheral wall defining a through-passage arranged and constructed to promote propagation of sound there-through. The acoustic duct portion has a length in a flow direction that is at least 50% of an average hydraulic diameter of the through-passage.

An air blower has an inlet muffler and an outlet muffler to reduce the noise of the air blower during operation. Each of the mufflers may have two sections. One section is configured to attenuate high frequency noise and the other section is configured to attenuate lower frequency noise. A tubular internal wall in each of the mufflers defines the through passage for each of the mufflers. A noise absorbent material may be fitted about the tubular wall within each muffler. A plurality of holes are formed along the tubular wall of each through passage to expose the through passage to the noise absorbent material. A heater plenum may be interposed between the blower plenum and the outlet muffler to heat the air from the blower plenum. A filter at the input muffler filters the air sucked into the air blower.

An air dryer includes a supporting base, a drying agent container, and an outer cover. The supporting base includes an inlet for receiving compressed air to be subject to a drying process and an outlet for delivering the processed compressed air that has undergone the drying process. The drying agent container is a container supported on the supporting base, contains a drying agent in the interior, and enables the drying process to be performed by passing the compressed air from the inlet through the drying agent. The outer cover surrounds the outer side of the drying agent container on the supporting base and defines a chamber for storing the compressed air between itself and the drying agent container. The supporting base includes first and second mounting surfaces, which are oriented in different directions, and a plurality of inlets, which are oriented in different directions and receive the compressed air.

An air dryer includes a supporting base, a drying agent container, and an outer cover. The supporting base includes an inlet for receiving compressed air to be subject to a drying process and an outlet for delivering the processed compressed air that has undergone the drying process. The drying agent container is a container supported on the supporting base, contains a drying agent in the interior, and enables the drying process to be performed by passing the compressed air from the inlet through the drying agent. The outer cover surrounds the outer side of the drying agent container on the supporting base and defines a chamber for storing the compressed air between itself and the drying agent container. The supporting base includes first and second mounting surfaces, which are oriented in different directions, and a plurality of inlets, which are oriented in different directions and receive the compressed air.

An aircraft auxiliary power unit sound attenuation apparatus includes a perforated body having a center aperture through which exhaust fluid passes, a backing member outwardly offset from the perforated body, a plurality of connecting members coupling the perforated body to the backing member to form a locally reacting sound attenuation member having a plurality of channels spanning outwardly from the perforated body to the backing member, and a bulk absorber disposed in each of the plurality of channels where the bulk absorber is in fluid communication with the exhaust fluid, where the locally reacting sound attenuation member is in fluid communication with an auxiliary power unit of an aircraft so that the plurality of channels are oriented in a direction crossing a pressure drop direction of an exhaust fluid flow passing through the center aperture and each channel circumscribes the center aperture.

An acoustic attenuator 20 for an engine booster such as a turbocharger 10 for an engine 4 is disclosed in which the acoustic attenuator 20 includes an attenuator chamber 28 in which is located at least one absorption media 140. The acoustic attenuator 20 is located adjacent an inlet port of the turbocharger 10 so as to attenuate any acoustic pressure waves by dissipative reaction with the absorption media 140 before they have chance to reach other components of a low pressure supply system 50 for the engine 4.

An acoustic attenuator 20 for an engine booster such as a turbocharger 10 for an engine 4 is disclosed in which the acoustic attenuator 20 includes an attenuator chamber 28 in which is located at least one absorption media 140. The acoustic attenuator 20 is located adjacent an inlet port of the turbocharger 10 so as to attenuate any acoustic pressure waves by dissipative reaction with the absorption media 140 before they have chance to reach other components of a low pressure supply system 50 for the engine 4.

An air blower has an inlet muffler and an outlet muffler to reduce the noise of the air blower during operation. Each of the mufflers may have two sections. One section is configured to attenuate high frequency noise and the other section is configured to attenuate lower frequency noise. A tubular internal wall in each of the mufflers defines the through passage for each of the mufflers. A noise absorbent material may be fitted about the tubular wall within each muffler. A plurality of holes are formed along the tubular wall of each through passage to expose the through passage to the noise absorbent material. A heater plenum may be interposed between the blower plenum and the outlet muffler to heat the air from the blower plenum. A filter at the input muffler filters the air sucked into the air blower.

The present invention relates to a combined heat exchanger and exhaust silencer for a vehicle, comprising a bypass valve configured to: in a first state, allow a flow path for exhaust gas to be open from an inlet to an outlet via an at least partly perforated bypass pipe, and in a second state, close said flow path, whereby at least a main portion of said exhaust gas is forced through a second flow channel comprising a heat exchanger pipe. The second flow channel is formed by an annular space between an at least partly perforated second pipe and an at least partly perforated third pipe. A sound absorbing material surrounds the bypass pipe and the third pipe, and is further arranged inside the second pipe.

The present invention relates to a combined heat exchanger and exhaust silencer for a vehicle, comprising a bypass valve configured to: in a first state, allow a flow path for exhaust gas to be open from an inlet to an outlet via an at least partly perforated bypass pipe, and in a second state, close said flow path, whereby at least a main portion of said exhaust gas is forced through a second flow channel comprising a heat exchanger pipe. The second flow channel is formed by an annular space between an at least partly perforated second pipe and an at least partly perforated third pipe. A sound absorbing material surrounds the bypass pipe and the third pipe, and is further arranged inside the second pipe.