【摘要】 吸声材料吸声、穿孔板吸声、阻抗复合吸声等被动吸声方法无法根据噪声频率的改变而对其吸声系数进行相应调整。为解决此问题，提出通过向消声器内部引入定量气流来调节吸声系数的主动吸声方法。首先通过一个驱动装置对穿孔板背后空腔的容积进行调整，使穿孔板先达到共振状态，然后在穿孔板背后的空腔内引入定量的气流，使引入的气流与排气气流在穿孔板背后的空腔内形成复合流场，在复合流场中，声波与气流的相互作用会产生非定常的脱落涡环现象，引起能量的转换和改变消声器内壁的阻抗性质，从而改变消声器的吸声系数。实验结果表明：提出的方法可在噪声频率不断改变的情况下有效地对吸声系数进行相应调整，使吸声系数始终维持在最大值。更多还原

【Abstract】 Passive sound absorption methods, such as sound absorption material, perforated panel and impedance compound sound absorption, cannot adjust the acoustic absorption coefficient according to the change of noise frequency. In order to solve this problem, an active sound absorption method is proposed to adjust the acoustical absorption coefficient by introducing quantitative airflow into the muffler. First of all, the volume of the cavity behind the perforated panel is adjusted by a driving device, so that the perforated panel achieves resonance. Then, the airflow with a certain speed is introduced into the cavity behind the perforated panel, and the introduced airflow gets together with the exhaust airflow to form a complex flow field inside the cavity. In the complex flow field, sound waves interacts with the airflow to generate an unsteady shedding vortex ring phenomenon, which causes energy conversion and the impedance characteristics change of the muffler wall so as to change the acoustical absorption coefficient of the muffler. The experimental results show that the proposed method can effectively adjust the acoustical absorption coefficient under the condition that the noise frequency changes constantly,so that the acoustical absorption coefficient can always keep the maximum.更多还原