Broadband metamaterial silencer for ventilation duct, and design method and application thereof

A broadband metamaterial silencer for a ventilation duct, wherein the broadband metamaterial silencer is a duct-outside broadband metamaterial silencer, or a duct-inside shunted broadband metamaterial silencer, or a broadband metamaterial degenerate sound absorber;

• the duct-outside broadband metamaterial silencer comprises a broadband sound insulator arranged outside the duct, a broadband sound absorber arranged outside the duct, or a combination of the broadband sound insulator arranged outside the duct and the broadband sound absorber arranged outside the duct;
• the duct-inside shunted broadband metamaterial silencer comprises a broadband sound insulator arranged inside the duct, a broadband sound absorber arranged inside the duct, or a combination of the broadband sound insulator arranged inside the duct and the broadband sound absorber arranged inside the duct;
• and
• the broadband metamaterial degenerate sound absorber comprises a plurality of perforated acoustic plates that are perpendicular to an airflow direction in the duct, and the duct-outside broadband metamaterial silencer, or the duct-inside shunted broadband metamaterial silencer, or a combination of the duct-outside broadband metamaterial silencer and the duct-inside shunted broadband metamaterial silencer;
• wherein the broadband sound insulator arranged outside the duct consists of a plurality of resonance units that are arranged in parallel and mutually independent, resonance behaviors of each resonance unit are single-frequency resonance behaviors and correspond to a specific frequency band of broadband noise to be reduced, and the resonance units achieve a sound insulating effect by reflecting sound waves at resonance frequencies and frequencies adjacent thereto;
• each resonance unit is arranged on a side wall of the ventilation duct and provided with an opening on the duct wall of the ventilation duct, or, each resonance unit is arranged on the side wall of the ventilation duct and provided with an opening on the duct wall of the ventilation duct, wherein a mesh covering material is provided at the opening of each resonance unit;
• the broadband sound absorber arranged outside the duct consists of a plurality of resonance units that are arranged in parallel and mutually independent, resonance behaviors of each resonance unit are single-frequency resonance behaviors and correspond to a specific frequency band of broadband noise to be reduced, and the resonance units achieve a sound absorbing effect by converting noise energy into heat energy and dissipating the heat energy;
• each resonance unit is arranged on the side wall of the ventilation duct and provided with an opening on the duct wall of the ventilation duct, or, each resonance unit is arranged on the side wall of the ventilation duct and provided with an opening on the duct wall of the ventilation duct, wherein a mesh covering material is provided at the opening of each resonance unit;
• the broadband sound insulator arranged inside the duct consists of a plurality of resonance units that are arranged in parallel and mutually independent, resonance behaviors of each resonance unit are single-frequency resonance behaviors and correspond to a specific frequency band of broadband noise to be reduced, and the resonance units achieve a sound insulating effect by reflecting sound waves at resonance frequencies and frequencies adjacent thereto;
• each resonance unit is arranged inside the ventilation duct and provided with an opening inside the ventilation duct, or, each resonance unit is arranged inside the ventilation duct and provided with an opening inside the ventilation duct, wherein a mesh covering material is provided at the opening of each resonance unit;
• the broadband sound absorber arranged inside the duct consists of a plurality of resonance units that are arranged in parallel and mutually independent, resonance behaviors of each resonance unit are single-frequency resonance behaviors and correspond to a specific frequency band of broadband noise to be reduced, and the resonance units achieve a sound absorbing effect by converting noise energy into heat energy and dissipating the heat energy;
• each resonance unit is arranged inside the ventilation duct and provided with an opening inside the ventilation duct, or, each resonance unit is arranged inside the ventilation duct and provided with an opening inside the ventilation duct, wherein a mesh covering material is provided at the opening of each resonance unit;
• and
• for the broadband metamaterial degenerate sound absorber, each perforated acoustic plate and the duct-outside broadband metamaterial silencer and/or the duct-inside shunted broadband metamaterial silencer corresponds to a specific frequency band of the broadband noise to be reduced;
• wherein each resonance unit comprises a rigid housing with an opening and the air in a cavity of the rigid housing;
• and
• the plurality of resonance units are arranged into geometric shapes with cavities of identical or different cross-sections, and each cavity is bent and folded on a certain plane, or on a curved surface, or in a three-dimensional space.