An ultra-low-frequency sound absorber and its application in noise reduction in ducts
Yi-jun Guan,
Yong Ge,
Cheng-hao Wu,
Qiao-rui Si,
Yun Lai,
Shou-qi Yuan,
Hong-xiang Sun
Affiliations
Yi-jun Guan
Research Center of Fluid Machinery Engineering and Technology, School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, China
Yong Ge
Research Center of Fluid Machinery Engineering and Technology, School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, China
Cheng-hao Wu
Research Center of Fluid Machinery Engineering and Technology, School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, China
Qiao-rui Si
Research Center of Fluid Machinery Engineering and Technology, School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, China
Yun Lai
National Laboratory of Solid State Microstructures, Department of Physics and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
Shou-qi Yuan
Research Center of Fluid Machinery Engineering and Technology, School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, China
Hong-xiang Sun
Research Center of Fluid Machinery Engineering and Technology, School of Physics and Electronic Engineering, Jiangsu University, Zhenjiang 212013, China
We demonstrate, both numerically and experimentally, an ultra-low-frequency sound absorber and its application in silenced ducts. The absorber comprises an array of resonant dual-spiral channel units (with a thickness of λ/47) backed by a wall, achieving near-perfect sound absorption with a fractional bandwidth of 18.3% around 73 Hz—a hallmark of ultra-low-frequency sound absorption. This characteristic arises from its effective near-zero modulus, with the absorbed energy dissipated through viscous losses in the unit channels. Furthermore, we explore the application of this ultra-low-frequency absorber in silenced ducts. By designing a composite absorber of five units with different parameters, we experimentally demonstrate efficient sound absorption in a duct with an enhanced fractional bandwidth of 60.6%. The average absorptance approaches 0.87. This designed absorber offers the advantages of deep-subwavelength thickness, ultra-low-frequency sound absorption, and broad bandwidth, opening up new possibilities for metamaterial-based absorbers in practical applications.
