Design and Optimization of a Muffler Integrated with an Adaptive Quarter Wave Tube for Noise Reduction in Commercial Vehicles

With rising concerns on internal combustion engine noise levels in commercial vehicles, it is necessary to attenuate noises present in specific frequency bands. This can be achieved with the implementation of a quarter wave tube on the present exhaust system. Historically such passive attenuators have been efficient only at specific engine speeds and exhaust gas temperatures. A new folded adaptive quarter wave tube design is proposed here which can give significant noise attenuation at various engine operating conditions. The proposed design eliminates the requirement of complex electronic actuating mechanisms for the adaptive quarter wave tubes and replaces the same by perforated diaphragms and adjustable end plates, which are more robust and effective. The module can replace the turbo S-flow single chambered muffler which is installed on most of the commercial vehicles. A design is conceptualized and developed using CAD tools. The performances for various combinations of quarter wave tube and muffler lengths are compared using analytical solutions and Finite Element Analysis/CFD. A comparative study on the transmission losses achieved by the current muffler design and the proposed design is also carried out. After comparison of the results, an optimum design for an integrated muffler system is proposed.