The exhaust silencer plays a very important role to muffle the noise coming in the blasts inside a combustion engine .It is also used to cleanse the exhaust gases with the aid of a catalytic converter. Get a lot more information regarding thermal insulation blankets
The exhaust design,as you might have noticed,features a bulge towards the end. The reason behind developing this bulge will be to supply a bigger cavity for the exhaust gases to flow,this mellows the sound coming directly from the engine and performs on the principle of a Helmholtz resonator.
One other design kind, that my physics teacher taught me about ,consists of splitting the exhaust stream into two with the enable of a secondary channel emerging from the pipe and after that reconnecting it back .the length of this secondary channel is such that when the two sound streams meet again ,they may be 180 degrees out of phase with respect to each other,this causes destructive interference at this junction! Hence muffling the sound.
The catalytic converter catalyzes the redox reaction of ‘carbon monoxide-hydrocarbons’(ox) and ‘nitrogen oxides’(red) ,which primarily helps in converting pollutants to less damaging gases.