有源吸声尖劈的实验研究

Experimental study of active acoustic wedge

提出了一种利用有源控制改善吸声尖劈低频声吸收的方法。实验研究了正入射下,有源控制系统对吸声尖劈低频段吸声性能的补偿效果;比较了用有源控制分别对吸声尖劈正面和背面声阻抗与空气阻抗进行匹配两种误差策略,发现将误差传声器放置在尖劈前更合理,既能保证较好的低频吸声效果,又能占用较少的空间。实验结果表明,有源控制系统与20cm长的传统尖劈相结合所构成的总长约40cm的有源吸声尖劈,在100-1000Hz频率段,吸声系数可以达到0.98-1.00,和80cm长的传统尖劈的吸声性能相当。

An approach to improving the low-frequency sound absorption of acoustic wedges is proposed by using active control of sound. Active compensation on low-frequency sound absorption of acoustic wedges under normal incident is studied experimentally in a square duct. By comparing two different strategies of implementing the impedance-matching boundary condition in front and at back of the acoustic wedge, it is found that the error microphones had better be put in front of the acoustic wedge. This can not only improve sound absorption at low frequencies but also save more space. For the 40 cm long active acoustic wedge which consists of a 20 cm long traditional acoustic wedge and an active control system, the sound absorption coefficients can be from 0.98 to 1.00 in the frequency range from 100 Hz to 1000 Hz. To achieve the same low frequency sound absorption with the traditional acoustic wedge, the length of the wedge needs to be about 80 cm long.