Study On The Noise Reduction Mechanism Of Low Frequency Noise In Substation With New Absorbing Materials

At present,there are many kinds of sound absorbing materials for noise reduction in substations.There are some defects in them,such as insufficient compression and low heat resistance,which can not meet the needs of noise reduction in substations.With the development of sustainable development,industrial solid waste has gained more and more attention,and the possibility of preparing raw materials as sound absorbing materials for substations is also widely studied.The purpose of this study is to prepare a new type of sound absorbing material using modified fly ash as the main raw material to explore its sound absorption property.In this paper,based on the characteristics of fly ash,a suitable chemical modifier is selected.Under the ultrasonic condition,the orthogonal experiment of two factors,temperature and time is set up,and the optimum conditions of ultrasonic combined chemical modification are obtained.With the modified fly ash as the main raw material,the grass wood ash as the foaming agent and the kaolin as the binder,the optimum ratio of the sound absorbing material was studied and the preparation was made.In the end,the sound absorption properties of the materials prepared at different sintering temperatures,different sintering times and different molding pressures are compared,and the effects of three factors on the performance of sound absorbing materials are investigated.The experimental results show that ultrasonic combined with alkali modification is the best modification method,which can make the fly ash have larger specific surface area and smaller pore size.The sound absorption coefficient and scanning electron microscope image of the sample were obtained by controlling the sintering temperature,it is found that the sample increases first and then decreases with the increase of the sintering temperature.By controlling the sintering time,the comparison results show that the sound absorption performance of the sample will increase with the increase of the sintering time of the sample,but the trend is not obvious when the sintering time is more than5h.By controlling molding pressure,the comparison results show that the sound absorption property of the sample increases first and then decreases with the increase of forming pressure.The best condition is the forming pressure is 2Mpa,the sintering temperature is 1100 degrees,and the sintering duration is5h.According to the findings,determine the most suitable conditions to produce finished products.The average volume density of finished products is 0.93g/cm~3,the compressive strength is 1.2Mpa,the average porosity of the porosity is about60%,the average sound absorption coefficient of the sample at low frequency is0.373,and the average sound absorption coefficient is 0.502.Finally,from the two aspects of the noise reduction mechanism and the sound absorption principle of porous materials,the principle of porous sound-absorbing material is introduced.