Design Of Pipeline Muffler And Research On Its Acoustic Performance

As a result of the continuous improvement of the power of various machines,noise pollution is increasingly common and serious.Aerodynamic noise generated by devices such as exhaust gas turbochargers and air compressors is a common type of noise.In the traditional design concept,the noise problem is often ignored,resulting in the discovery of excessive noise after the completion of product development,loss of competitive advantage,and even being unable to meet regulations and being forced to rectify.Therefore,it has certain significance in research on the de-noising of diesel exhaust turbochargers and the control of air compressor exhaust noise.The main work of this article is as follows:(1)Analyze the acoustic performance of several types of basic silencing units to obtain the effect of structural parameters of each silencing unit on its transmission loss.(2)Taking the intake muffler of a certain compressor as the research object,establish the geometric model and the finite element model.On the professional acoustic software Virtual.Lab Acoustics platform,the acoustic performance of the intake muffler was simulated and its transmission loss was obtained.Then,the muffler was subjected to a transmission loss experiment to verify the simulation results.Based on the simulation and experimental results of the muffler,an improved design was made.The change in the transmission loss of the intake muffler when the perforated plate was arranged on both sides of the sound-absorbing plate was studied.As a result,it was found that the arrangement of perforated plates on both sides of the sound-absorbing plate improved the transmission loss of the muffler by about 5 dB in the range of 800 to 2500 Hz.(3)Measure the exhaust noise of a certain type of compressor,analyze the frequency spectrum of exhaust noise,and according to the basic knowledge and design concept of the muffler,design three solutions for the exhaust muffler of this type of compressor.Using Virtual Finite Element software Virtual.Lab simulation results,the results show that: due to the limitation of the linear shape of the compressor volute structure,a single expansion chamber muffler has a small expansion ratio and results in unsatisfactory attenuation.The perforated pipe mufflerof scheme two has an average noise reduction amount of 3.4 dB in the range of800-3000 Hz in the high-frequency range,which still cannot meet the requirements.The third solution is a resonance chamber muffler,whose noise reduction is almost zero in the low frequency range of 20~800Hz,but the average noise reduction amount reaches 5.2dB in the middle to high frequency range of 800~3000Hz,and the maximum noise reduction is 32.7dB.The peak frequency distribution 1080 Hz,to meet the requirements of the project partners.(4)Aiming at the air exhaust noise of a certain air compressor is relatively large,which has an impact on the physical and mental health of the workers.The modeling and calculation of the original muffler exhaust muffler was carried out.It was found that the original muffler was unreasonable in design,its noise reduction effect was not ideal in the frequency range of 20~3000 Hz,and the average noise attenuation was only 7.8dB.Therefore,an improved design was needed.Achieve better noise reduction.Three mufflers were designed using a combination of throttling buck plate,chip silencer channel and small hole injection layer.They were simulated and analyzed respectively,and the admittance relationship was transmitted through the grid definition on both sides of the perforated plate to simulate the muffler.The acoustic properties of the perforated plate inside the muffler can simplify the finite element mesh processing of the muffler.Comparing and analyzing the anechoic effects of the three schemes,scheme 3 has the best effect.Then empirical formulae were estimated for scheme 3 to verify the simulation results.The results show that the acoustic finite element simulation result of scheme 3 is similar to the transmission loss estimated by the empirical formula.It has an ideal noise cancellation effect in a wide frequency range of 20~3000 Hz.Noise reduction can reach 57 dB.In summary,this paper separately studied three typical types of mufflers.The first type is a resistive muffler.The simulation and experiment of the resistive muffler are compared and analyzed,and an improved design is made.Good results have been achieved.The second type is the impedance composite muffler.The first type of resistive muffler is used for research,and the air compressor is designed and empirically evaluated for comparative analysis.The third type is the resonance muffler,which has the characteristic of a typical resonance muffler,that is,it has a strong frequency selectivity.The study of three types of mufflers has certain representativeness and significance.