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Numerical Investigation of the Effect of Muffler Geometry on Engine Performance

Muffler is a part of an exhaust system fitted to IC engines for damping noise and to convey hot gases from the combustion chamber. Several research efforts have been put into the study of muffler. This is due to their significant effects on noise reduction, fuel consumption, efficiency and life span of engine. Good muffler minimizes noise, back pressure and engine fuel consumption. Currently, the price of petroleum products in the global market is high and very unstable. Therefore, conservation of fuel is very important, particularly to the end user. This study seeks to examine the effects of baffle holes on the fluid flow characteristics and forces on the baffle walls. Three muffler models were designed using Autodesk Investor 2015. ANSYS 16.0 was used as the CFD working tools to predict the flow characteristics and forces on the walls. Samples A, B and C were modeled to have 7, 13 and 26 holes, respectively while the diameter of the holes for samples A, B and C were 50, 37.5 and 25 mm, respectively. Navier-Stokes and energy transport equations govern the three muffler models. Muffler sample A displayed the lowest backpressure of 20.235 Pa, average wall temperature of 986.311 K and best fuel efficiency characteristics. Sample B had the lowest forces on the wall while Muffler C has the least advantage when compared with other models. Muffler sample B gave the optimum design characteristic considering fuel consumption engine efficiency and muffler durability.