Research On Exhaust Noise Characteristics Of Loder And Optimization Design Of Muffler

With the rapid development of our country industry, the loader has been widely used, but the problem of exhaust noise, which seriously affects driver's comfort and reduce work efficiency,is becoming more and more serious. It is of great significance to take effective measures to control exhaust noise. This dissertation is aimed at optimizing the exhaust noise characteristics of the loader and muffler.Based on the loader exhaust noise in the experiment, and the spectrum of exhaust noise composition and properties were studied. It was concluded that the fundamental frequency and gas column resonance noise was the major source of noise, and concentrated in low and middle frequency, and resistant muffler was mainly used to control the low and middle frequency noise. To establish the basic structure of resistant muffler model in this dissertation, such as the length of expansion cavity, the diameter of expansion cavity, the cavity number and two cavity muffler under different cavity length, different position offset outlet pipe, intubation tube, import and export side.Using LMS.Virtural.Lab and Fluent software to analysis the acoustics performance and fluid performance, this study provides a new way of optimization design of the muffler. The transfer matrix method in acoustic performance calculation is adopted to establish the numerical model of muffler transmission loss and semi-empirical calculation method in fluid mechanics performance calculation is adopted to establish the numerical model of muffler pressure loss, and the model was validated. The muffler structure parameters were generated by Latin hypercube design,based on the design of experiment(DOE),thecontributionHthe main effectH interaction effect of the muffler structure parameters were analyzedbthis study provides a basis for muffler further numerical optimization.In the study of muffler optimization design, usethe results of finite element simulation of muffler to guide structure design and use adaptive simulated annealing algorithm(ASA) and multi-objective simulated annealing algorithm(MOSA) in the numerical method to optimize and design the muffler.The intubation tube structure can increase the transmission loss of muffler and reduce the pressure loss in the simulation analysis, the intubation tube structure was used in the new design of muffler,the results showed that the acoustic performance and fluid mechanical performance of muffler were improved effectively.The DOE method can effectively identify the parameters which affect muffler performance in the numerical optimization method, and simplify the optimization model of muffler.The single objective and multi-objective optimization model were established respectively in the exhaust noise of peak frequency as the goal of transmission loss,the muffler were optimized by ASA and MOSA in single objective and multi-objective optimization respectively,which in the process of multi-objective optimization, to optimize the double goals and three goals.The results showed that the transmission loss of muffler corresponding to the peak frequency through single objective optimization can reach maximum, while multi-objective optimization can make overall optimization results better,but the three goals of Pareto optimal solutions was more than the double goals, while the final optimization results were similar to those of the double goals, considering the practical engineering application, double target should be choosed to optimize the muffler. The results and methods of this study are helpful for optimization design of muffler.