Aqua silencer
Chapter 1
Introduction
1. Introduction
1.1EXHAUST SILENCERS
Engine exhaust noise is controlled through the use of silencers and mufflers. Generally speaking, there is no technical distinction between a silencer and muffler and the terms are frequently used interchangeably. A silencer has been the traditional name for noise attenuation devices, while a muffler is smaller, mass-produced device designed to reduce engine exhaust noise.
1.2 SILENCER SELECTION FACTORS
The use of an exhaust silencer is prompted by the need to reduce the engine exhaust noise. In most applications the final selection of an exhaust silencer is based on a compromise between the predicted acoustical, aerodynamic, mechanical and structural performance in conjunction with the cost of the resulting system.
1.2.1 Acoustical performance
The acoustical performance criterion specifies the minimum Insertion Loss (IL) of the silencer, and is usually presented in IL values for each octave band as well as an overall expected noise reduction value. The insertion loss is determined from the free-field sound pressure levels measured at the same relative locations with respect to the outlet of the un silenced and silenced systems. The IL of a silencer is essentially determined by measuring the noise levels of piping systems before and after the insertion of a silencer in the exhaust stream. IL data presented by most manufacturers will typically be based upon insertion of the silencer into a standard piping system consisting of specified straight runs of piping before and after the silencer. Exhaust system configurations as well as mechanical design can have a substantial impact on the performance of and exhaust silencer and should be considered at the time of specification. Raw exhaust noise levels should be obtained from the engine manufacturer to determine the necessary noise reduction requirements of the proposed silencer. Specific installation conditions and exhaust noise levels will aid the
Introduction
1. Introduction
1.1EXHAUST SILENCERS
Engine exhaust noise is controlled through the use of silencers and mufflers. Generally speaking, there is no technical distinction between a silencer and muffler and the terms are frequently used interchangeably. A silencer has been the traditional name for noise attenuation devices, while a muffler is smaller, mass-produced device designed to reduce engine exhaust noise.
1.2 SILENCER SELECTION FACTORS
The use of an exhaust silencer is prompted by the need to reduce the engine exhaust noise. In most applications the final selection of an exhaust silencer is based on a compromise between the predicted acoustical, aerodynamic, mechanical and structural performance in conjunction with the cost of the resulting system.
1.2.1 Acoustical performance
The acoustical performance criterion specifies the minimum Insertion Loss (IL) of the silencer, and is usually presented in IL values for each octave band as well as an overall expected noise reduction value. The insertion loss is determined from the free-field sound pressure levels measured at the same relative locations with respect to the outlet of the un silenced and silenced systems. The IL of a silencer is essentially determined by measuring the noise levels of piping systems before and after the insertion of a silencer in the exhaust stream. IL data presented by most manufacturers will typically be based upon insertion of the silencer into a standard piping system consisting of specified straight runs of piping before and after the silencer. Exhaust system configurations as well as mechanical design can have a substantial impact on the performance of and exhaust silencer and should be considered at the time of specification. Raw exhaust noise levels should be obtained from the engine manufacturer to determine the necessary noise reduction requirements of the proposed silencer. Specific installation conditions and exhaust noise levels will aid the
References: FROM NET 29) 1) Beranek, L. L. and Ver, I. L. Noise and Vibration Control Engineering, John Wiley & Sons Inc, 1992. 30) 2) Bradley, D. On-Site Power Generation, A Reference Book, Chapter 19 Exhaust silencers, Third Edition, Electrical Generating Systems Association, 2000. 31) 3) Internal Combustion of Engines - M. L. Mathur R.P. Shrma .P. Shrma . 32) 4) Environmental Pollution Analysis - Khopkar 33) 5) Engg. Chemistry - Jain & Jain 34) 6) Scribd.comScribd.com 35) 7) Freepatentsonline.comFreepatentsonline.com 36) 8) En.wikipedia.org , En.wikipedia.org