结构化的复合声场及其操纵颗粒有效性的实验研究

Experimental study on structured complex acoustic field and its effectiveness of particle manipulation

基于装置各部件固有频率相等的方法,设计制作了一种在平面声腔侧壁离散对称布置16极Helmholtz声源的实验装置,研究了平面声腔内由16极Helmholtz声源构造的复合声场及其对颗粒的操纵特性.通过理论和实验研究了Helmholtz声源的频率特性、平面声腔的谐振特性、平面声腔内复合声场的时空变化特性以及复合声场对平面声腔内充注的烟气颗粒操纵的有效性.结果表明:运行频率为1.805 k Hz时,16极Helmholtz声源耦合的平面声腔能够实现同步谐振;平面声腔内形成了声压幅度逐渐衰减的环形复合声场;烟气颗粒被聚集在靠近壁面约0.5个波长的环形区域内,在平面声腔的中部形成了无颗粒区,颗粒聚集区与无颗粒区的面积比约为16∶9.

Based on the method with equal natural frequencies for all equipment components,an experimental device symmetrically and discretely distributed by 16 Helmholtz sound sources（ HSSs） on the sidewall of a planar acoustic cavity was designed and fabricated. The complex acoustic field created by 16 HSSs in the cavity and its manipulation on particle were studied. The frequency characteristics of HSS,the resonance of planar acoustic cavity,the time-space variation feature of acoustic field and its manipulating effectiveness on filling smoke particles in planar acoustic cavity were theoretically and experimentally researched. The results showthat the synchronization resonance of planar acoustic cavity coupled to 16 HSSs occurs at the working frequency 1. 805 k Hz. An amplitudedecaying annular complex acoustic field is generated in planar acoustic cavity. Smoke particles are gathered in the annular region about 0. 5 a wavelength near the wall. There forms a particle-free zone in cavity central,and the area ratio of particle clusters to no particles is about 16∶ 9.