Performance Evaluation of Tractor Mufflers for Human Comfort

Tractor mufflers constructed with amalgamation of perforated ducts, baffles or perforated baffles and expansion chambers for acoustic attenuation are commonly used. Poorly designed mufflers provide limited noise reduction and high back pressure, resulting in low fuel efficiency. Sound pressure mapping technique was adopted to identify major contributor of noise for a 47.6 PS tractor. An experiment was carried out to evaluate different muffler designs with regard to sound pressure levels and exhaust back pressure at varying operating conditions. Each muffler design produced noise greater that 90 dBA Leq at operator’s ear level at rated engine speed, and was more than the exposure limit of noise for 8-h work day recommended by ISO and OSHA. Long exposure of this noise might cause occupational disease to operator. Noise reduction was observed in one of the mufflers near rated engine speed with low back pressure with better fuel efficiency. Sound pressure at operator ear level, back pressure and fuel consumption were found within 90.3-92.8 dBA, 1.765-2.157 kPa and 2.65-3.35 l.h-1, respectively, near engine rated speed.