A silencer

A silencer comprises a duct 14 having an inner surface 16 defining a bore 18, an outer surface 20 exposed to the external atmosphere, and a plurality of micropassages for converting acoustic energy within the gas flow into thermal energy. Micropassages are defined as having a width w, as measured al...

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Bibliographische Detailangaben
Hauptverfasser:	William John Lamb, Ignacio Justo Perez Pablos
Format:	Patent
Sprache:	eng
Schlagworte:	ACOUSTICS ACOUSTICS NOT OTHERWISE PROVIDED FOR BLASTING ENGINE PLANTS IN GENERAL ENGINEERING ELEMENTS AND UNITS GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNALCOMBUSTION ENGINES GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES ORENGINES IN GENERAL GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVEFUNCTIONING OF MACHINES OR INSTALLATIONS HEATING JOINTS OR FITTINGS FOR PIPES LIGHTING MACHINES OR ENGINES IN GENERAL MEANS FOR THERMAL INSULATION IN GENERAL MECHANICAL ENGINEERING METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING,NOISE OR OTHER ACOUSTIC WAVES IN GENERAL MUSICAL INSTRUMENTS PHYSICS PIPES SOUND-PRODUCING DEVICES STEAM ENGINES SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING THERMAL INSULATION IN GENERAL WEAPONS
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Beschreibung
Zusammenfassung:	A silencer comprises a duct 14 having an inner surface 16 defining a bore 18, an outer surface 20 exposed to the external atmosphere, and a plurality of micropassages for converting acoustic energy within the gas flow into thermal energy. Micropassages are defined as having a width w, as measured along the longitudinal axis A of the bore, of less than one millimetre, eg 0.1mm. The micropassages may be microslits 22, or microperforations. The depth d of the micropassages, orthogonal to the axis A, is preferably less than 2mm, eg 1mm. The microslits 22 may extend partially or fully around the longitudinal axis A. If annular microslits 22 are provided, joints are formed between adjacent duct sections. Each micropassage (i) is disposed at one of a plurality of axial locations which are spaced apart along the axis A, and (ii) extends between the inner and outer surfaces 16, 20 of the duct 14. The axial locations register with pressure maxima of a plurality of resonant frequencies of sound waves generated by the source, eg a motor of a fan, fan heater, humidifier, vacuum cleaner or hairdryer.