​Noise Reduction Solution for 926 High-Pressure Centrifugal Fan

Noise Reduction Solution for 926 High-Pressure Centrifugal Fan1. Increase cascading air load to reduce peripheral speed. The 926 high-pressure centrifugal fan employs powerful forward-curved blades and multi-segment propellers to enhance cascading aerodynamic load. Under identical airflow and pressure conditions, the peripheral speed of the impeller blades enables significant noise reduction in the 926 high-pressure centrifugal fan. 2. Incorporate zigzag structures on both inlet and outlet sides of the 926 high-pressure centrifugal fan's moving blades. This induces early turbulent flow in the laminar boundary layer over the dynamic blades, preventing vortex shedding caused by unstable fluctuations. Consequently, laminar boundary layer instability and associated noise are minimized. 3. The periodic pulsation of airflow velocity within the cascaded impellers of the inclined Polytan centrifugal fan generates periodic pulsating aerodynamic forces. These forces interact with the Polytan structure to produce rotational noise in the region upstream of the vortex tongue. By tilting the shaft, the area of in-phase pulsating aerodynamic forces is reduced, thereby decreasing radiated noise. 4. Adding turbulence devices (metal mesh) at the inlet (or outlet) of the 926 high-pressure centrifugal fan blades enables the laminar boundary layer on the blade trailing edge to instantly transition into a turbulent boundary layer. This delays or even prevents boundary layer separation. The mesh at the blade trailing edge rapidly and uniformly increases air velocity and pressure gradient downstream. When positioned within vortex regions, the mesh significantly reduces swirling areas, further lowering noise levels. 5. Optimal Convolution Tank Clearance and Radius As airflow moves relative to the blade, the velocity and pressure at the trailing edge are lower than in the main flow region. This creates uneven distribution of airflow velocity and pressure downstream of the cascade. This uneven flow rotates. Since the 926 high-pressure centrifugal fan features a turbine at its air outlet, the interaction between this unstable flow and the turbine generates noise, with intensity increasing closer to the turbine. Generally, a larger tongue radius reduces eccentricity. 6. The 926 high-pressure centrifugal fan incorporates acoustic resonators on the shaft. When sound waves reach these resonators, the gas and cavities at the small aperture openings oscillate back and forth due to the sound wave action. The moving gas possesses mass, which resists the propagation of sound waves. Simultaneously, as sound waves enter the orifice opening, significant acoustic energy is dissipated through friction and thermal loss caused by the neck wall. Additionally, the gas-filled cavity possesses properties that counteract pressure fluctuations originating from the orifice. These combined effects reduce noise generation as gas passes through the resonator.