高声强下多狭缝共振腔的吸声性能

为深入理解高入射声强下多狭缝共振腔吸声机理,采用低频散低耗散的计算气动声学方法对二维多狭缝共振腔开展直接数值模拟研究.首先对标准单狭缝共振腔计算结果进行验证,随后相同的数值模拟方法被应用于相同穿孔率的多狭缝共振腔的数值模拟中.结果显示:高声强下涡脱落对吸声系数的贡献占据了主导地位,各入射频率下均超过68%.多狭缝低频时会导致脱落涡总能量的下降,而高频时升高;而黏性耗散作用随着共振腔狭缝数目的增加而增强.因此综合作用下低频时多狭缝共振腔对吸声效果影响不大,但在高频时多狭缝共振腔有更好的吸声效果. 

Sound absorption characteristics of resonator with multi slits under high sound pressure level

For better understanding of the sound absorption mechanism of resonator with multi slits under high incident sound pressure level(SPL), direct numerical simulation(DNS) using low dispersion and low dissipation computational aeroacoustics(CAA) method was carried out to deal with 2-D resonator with multi slits. Good agreement was first found in validation of standard resonator with single slit through comparison. Then the same numerical methods were applied in numerical simulation of multi slits resonators with the same perforation ratio. Results show that under high SPL, vortex shedding contributes dominantly to the sound absorption coefficient, over 68% in each incident frequency. Multi slits could enhance the viscous dissipation of acoustic energy while vortex shedding was suppressed in low frequencies and strengthened in high frequencies, resulting in better sound absorption capability of resonator with multi slits in relatively higher incident frequencies, but with weak influence on low incident frequencies.