Car exhaust muffler performance simulation of fluid flow and acoustic

Vehicle noise, exhaust noise as an important part of the NVH performance of the vehicle significantly, muffler exhaust noise is the main means of control. Design of high performance muffler, low pressure loss of the muffler car noise control system is an important topic in the field. Traditional design methods and test according to the designer experience, the basis of one-dimensional plane wave theory is difficult to correctly simulate the actual three-dimensional fluctuations and other factors, and long cycle, high cost and low efficiency. In recent years, based on numerical simulation of the muffler design improvements began to be used, in which three-dimensional finite element method because of its high accuracy and simulate the effect of three-dimensional fluctuations and other factors become more accurate muffler design an effective method for improvement. Acoustic performance and aerodynamic performance is to evaluate the two main aspects of the muffler. In this paper, the basic muffler muffler on the basis of theory, using three-dimensional acoustic finite element method and finite volume method, respectively, in SYSNOISE software and FLUENT software to complete the acoustic characteristics of the muffler and the flow field of numerical simulation. Sound field simulation by muffler transmission loss, and to consider the outside temperature, flow rate, the tail pipe reflection practical factors on the muffler performance; flow field simulation has been within the system flow rate, temperature, pressure, turbulent kinetic energy distribution of the flow characteristics and regeneration noise, and the calculated pressure loss. The simulation results analysis and comparison of engine exhaust noise source identified improvement goals, to retain the original muffler dimensions, the internal structure of the muffler to improve design. Actual improvement process, the muffler unit to do all further simulation analysis to calculate the transmission loss and sound mode and the combined pressure of chart analysis, concrete improvements, and then make the overall program. Overall program, considering the acoustic and aerodynamic performance, to further improve the program, the basic objective to improve. Finally, numerical simulation based on improved muffler design was summarized and presented the basic process improvement and general methods. In this paper, the numerical simulation of the exhaust muffler to provide reference for the trial, and to improve the design of the muffler has accumulated some experience and methods can be used as future muffler noise prediction and design improvement of a reference. Keywords: exhaust muffler, finite element, acoustic characteristics, flow characteristics, improved design