具有分流对冲的穿孔管吸声方法

Sound Absorption Method of Perforated Tube with Airflow Shunt Hedge

发动机的排气气流流速是影响消声器综合性能的重要参数,随着排气气流流速增加消声器内产生的再生噪声增加,使得消声器的吸声效果变差。为解决此问题,提出通过将排气气流进行分流与对冲降低排气气流流速来提高吸声效果的吸声方法。首先通过一个锥形分流单元将进入消声器的气流进行分流,分流后的气流通过穿孔管上的小孔进入到穿孔管内腔,使气流在穿孔管内腔发生对冲,从而降低排气气流流速提高吸声效果。通过对整体结构进行消声子单元划分、传递矩阵计算、传递损失自变量与因变量函数关系分析得到传递损失的影响因素与变化特性,并对理论模型进行实验验证。实验结果表明:提出的吸声方法可在高速排气气流的情况下,使传递损失始终维持在稳定状态,以入口气流流速从15 m/s增加到45 m/s为例,传递损失从26.5 dB降低到24.5 dB,降幅为0.075%,证明了该结构具有良好且稳定的吸声效果。

The exhaust flow velocity of the engine is an important parameter affecting the comprehensive performance of the muffler.With the increase of exhaust flow velocity,the regenerative noise in the muffler increases,which makes the sound absorption effect of the muffler even worse.In order to solve this problem,a sound absorption method is proposed to reduce the flow rate of exhaust air by diverting and hedging the exhaust air so as to improve the sound absorption.The airflow into the muffler is firstly diverted by a conical diverter element,and then the airflow enters the cavity of the perforated tube through the holes on the perforated tube.The airflow impacts in the cavity of the perforated tube,so that the flow rate of the exhaust airflow is reduced and the sound absorption effect is improved.In this paper,the whole structure of the perforated tube is analyzed through acoustic sub-element dividing and transfer matrix calculation.The function relationship between the independent variable and the dependent function of the transfer loss is analyzed.The influence factors and the characteristics of the transfer loss are obtained.And the theoretical model is verified by experiments.The results of the experiment show that the proposed sound absorption method can keep the transmission loss at a stable state under the condition of highspeed exhaust flow.For example,when the inlet flow velocity increases from 15 m/s to 45 m/s,the transmission loss decreases from 26.5 dB to 24.5 dB,the decrease magnitude reaches 0.075%,which proves that this structure has a good effect of sound absorption.