Centrifugal Fan Noise Reduction via Segmented Casing and Integral Impeller
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Solution Overview
Problem
Centrifugal fans face challenges in reducing high discrete frequency noise and wideband noise, particularly due to turbulent flow, which affects their installation in various apparatuses, and there is a need to improve airflow efficiency and productivity while minimizing noise and power consumption.
Innovation Solution
The design incorporates an open-type casing with an upper and lower casing configuration, featuring an upper shroud and blades that taper outward, an inclined blade shape, and a protrusion on the lower casing to enhance airflow and reduce noise by minimizing backflow and vortex formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If traditional centrifugal fan design is used, then structural simplicity is maintained, but high discrete frequency noise and wideband noise increase due to turbulent flow
Solution Approach 1:
The casing is divided into an upper casing and a lower casing that can be assembled separately. The upper casing includes a bell mouth portion and a body portion, while the lower casing includes a discharge portion. This segmentation allows for optimized airflow control in each section while maintaining overall structural simplicity and reducing noise through improved flow management.
Solution Approach 2:
The bell mouth portion is designed with a curved, bell-shaped inlet that smoothly guides air into the impeller. This curvature eliminates sharp edges and corners that would cause flow separation and turbulence, thereby reducing both high discrete frequency noise and wideband noise while maintaining efficient airflow.
2Productivity
If complex blade shaping is used, then airflow efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The impeller is designed as an integrated component where the blades are directly formed as part of the impeller body structure. The blades feature optimized aerodynamic shapes with proper curvature and thickness distribution to maximize airflow efficiency while being manufacturable as a single piece, thereby combining high performance with manufacturing simplicity.
3Object-generated harmful factors
If gap reduction measures are taken, then backflow suppression improves, but manufacturing precision requirements increase
Solution Approach 1:
A seal member is introduced as an intermediary component between the upper and lower casings to effectively seal the gap without requiring extremely tight manufacturing tolerances. This seal member prevents backflow of air from the discharge side to the suction side while accommodating normal manufacturing variations, thereby suppressing harmful backflow without imposing excessive precision requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves airflow efficiency, reduces noise levels, and maintains high productivity by allowing integral molding of the impeller, thus addressing the noise and efficiency challenges faced by traditional centrifugal fans.
Implementation Method 1
discharges the air outward in the radial direction of the impeller by a centrifugal action from the rotation of the impeller
Data Source
AI summary
A centrifugal fan includes: a casing having an upper casing with an air suction opening, a lower casing, and a plurality of support members disposed between the lower casing and the upper casing with air discharge openings provided between the support members; an impeller disposed between the upper and lower casings, and including an annular upper shroud provided on an upper casing side, a base plate integrally formed with the annular upper shroud, and a plurality of blades arranged along a circumferential direction between the annular upper shroud and the base plate; and a fan motor which rotates the impeller. A plurality of recesses are provided on the upper surface of the upper casing, and formed to surround the air suction opening, and a plurality of ribs are radially provided around the air suction opening and between the adjacent recesses.