Design And Study Of A New Micro-Perforated Tube Muffler

As the global economy continues to grow and people’s living standards continue to improve,the issue of noise pollution is receiving more and more attention.In today’s world,how to effectively reduce noise has become an important topic of academic research.When consumers are shopping for air conditioners,the amount of noise is often seen as a very important selection indicator.For the noise problem generated by the compressor ventilation ducts in air conditioning systems,the addition of mufflers is generally used to reduce the noise.At present,the muffling band of traditional micro-perforated tube mufflers is not wide enough to meet engineering requirements,and low frequency noise reduction has been a challenging problem.To address these problems,this study proposes two new micro-perforated tube muffler structures and analyses them in detail as follows:Firstly,with reference to the existing research results and aiming at improving the muffling performance,two structural solutions of micro-perforated tube muffler were proposed,namely honeycomb sandwich micro-perforated tube muffler and layered micro-perforated tube muffler with built-in spiral plate.The muffler’s sound dissipation characteristics were studied in depth by means of finite element analysis software,and the transmission loss curve and sound pressure level distribution diagram were derived.The influence of structural parameters on the transmission loss of the micro-perforated tube muffler was analysed,including the micro-perforated aperture diameter,micro-perforated tube wall thickness,perforation rate and expansion chamber diameter.Next,the orthogonal experimental method was used to optimise the structural parameters of the layered micro-perforated tube muffler with built-in spiral plates.The experimental factors and levels were determined to obtain the best combination of structural parameters affecting the muffling performance.The muffling performance of the muffler before and after optimization was compared,and the transmission loss of the optimized muffler in the frequency range of 0-3000Hz was obviously improved.Finally,the performance of the two new micro-perforated tube mufflers was compared with that of the existing micro-perforated tube muffler structures with a spacer plate in the expansion chamber in the literature.Micro-perforated tube muffler specimens were machined and the transmission loss of the new micro-perforated tube muffler was measured at different frequencies using the two-load method to verify the accuracy of the simulation results.After the above simulation analysis and experimental verification,the layered micro-perforated tube muffler with built-in spiral plate shows good noise reduction performance for low frequency broadband noise and can achieve the expected effect.