Centrifugal fan
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Solution Overview
Problem
Double suction type centrifugal fans experience turbulence and abnormal noise due to increased external static pressure, leading to decreased air volume and efficiency.
Innovation Solution
The design includes a rotatable impeller with first and second inlets and an outlet, featuring a sidewall with convex parts that guide air flow through a scroll-shaped path, reducing turbulence and noise by ensuring uniform airflow and pressure distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If air is extruded in radial direction by rotation of the impeller in a double suction type centrifugal fan, then air volume is increased, but turbulence is generated in the fan housing leading to abnormal noise and decreased static pressure
Solution Approach 1:
The fan housing is divided into separate chambers with partition walls that segment the airflow paths from different inlets. This segmentation prevents mixing of air currents at different pressures and reduces turbulence, allowing high air volume operation without abnormal noise
Solution Approach 2:
Different regions of the fan housing are designed with different structural characteristics - some regions have smooth curved surfaces for gradual flow transition, while other regions have partition walls for flow separation. This local differentiation optimizes airflow in each region to prevent turbulence while maintaining high air volume
2Stress or pressure
If external static pressure is increased, then air blowing capability is improved, but turbulence is generated in the fan housing causing drop in static pressure and air volume
Solution Approach 1:
The inlet passages are designed with gradual expansion sections and smooth transitions before air enters the impeller suction area. This preliminary flow conditioning prevents turbulence generation when external static pressure increases, maintaining stable air volume
Solution Approach 2:
The fan housing incorporates curved and rounded flow passages instead of sharp angles. The curved inlet passages and rounded corners guide air smoothly into the impeller, preventing flow separation and turbulence even under high external static pressure conditions
3Ease of operation
If a scroll-shaped flow path is used to guide air toward the outlet, then airflow is directed efficiently, but turbulence is generated when air currents from both sides are mixed in one space
Solution Approach 1:
The scroll-shaped flow path is divided into separate sections by partition walls, with each section handling air flow from one inlet independently. This prevents mixing of counter-rotating air currents that would cause turbulence, while still providing efficient airflow guidance to the outlet
Solution Approach 2:
The flow path design incorporates asymmetric features that match the rotational direction of the impeller blades. The scroll shape and passage angles are optimized for the specific rotation direction, improving airflow guidance efficiency while minimizing turbulence generation
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 enhances airflow stability, reduces noise, and maintains high air volume under high external static pressure, improving the overall efficiency of the centrifugal fan.
Implementation Method 1
a centrifugal fan rotating at high speed to generate a centrifugal force... air is extruded in a radial direction by rotation of the impeller
Implementation Method 2
as static pressure of air outside the fan housing is increased, turbulence of air is generated in the fan housing
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A centrifugal fan is provided. First blades and second blades are disposed at both sides of a main plate, respectively. A first convex part and a second convex part are formed at a fan housing to correspond to the first blades and the second blades, respectively. Thereby, an airflow generated by the first blades and an airflow generated by the second blades are guided to be divided into the first convex part and the second convex part, respectively.