Centrifugal Blower Wheel Notched Fan Blades
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Solution Overview
Problem
Forward-curved centrifugal blower wheels with reduced leading edge blade angles suffer from buffeting and inefficiency, requiring smaller inlet rings to prevent poor operation, which offsets potential efficiency gains.
Innovation Solution
Incorporating notches on the leading edges of fan blades adjacent the inlet of the blower wheel, with specific notch area and blade angle configurations, to enhance efficiency without buffeting issues and allow for full-sized or oversized housing inlet rings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the leading edge blade angle is reduced to improve efficiency, then energy efficiency is improved, but the blower wheel experiences buffeting and operates poorly
Solution Approach 1:
The patent applies local quality by introducing notches only at specific locations on the fan blades (leading edges and/or trailing edges) rather than modifying the entire blade structure. This localized modification allows the blade angle to be reduced for efficiency while the notched regions provide localized flow control to prevent buffeting, resolving the contradiction between efficiency improvement and operational stability.
2Reliability
If the inlet ring size is reduced to prevent buffeting, then operational stability is improved, but the housing inlet ring cannot be full-sized or oversized
Solution Approach 1:
The patent changes the geometric parameters of the fan blades by introducing notches with specific dimensions (depth, width, positioning) to alter the airflow characteristics. This parameter modification allows the system to maintain stable operation with full-sized or oversized inlet rings, eliminating the need to reduce inlet ring area to prevent buffeting.
3Loss of energy
If longer chord length blades are used with reduced leading edge blade angle, then efficiency is improved, but the blower wheel suffers from buffeting
Solution Approach 1:
The patent applies local quality by introducing notches only at specific locations on the fan blades (leading edges and/or trailing edges) rather than modifying the entire blade structure. This localized modification allows the blade angle to be reduced for efficiency while the notched regions provide localized flow control to prevent buffeting, resolving the contradiction between efficiency improvement and operational stability.
Solution Approach 2:
The patent converts the potentially harmful effect of long chord length blades (which cause buffeting when combined with reduced blade angles) into a benefit by strategically notching these same blades. The notches transform the long blade configuration from a source of instability into an efficient, stable design by using the extended blade length for improved aerodynamic performance while the notched regions control flow separation.
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
The solution achieves higher efficiency and stability by reducing buffeting, enabling operation with larger inlet rings and maintaining pressure generation capabilities, thus improving overall blower wheel performance.
Implementation Method 1
expelling such air or gas through the fan blades via the centrifugal force acting on the air or gas between the fan blades
Data Source
AI summary
A forward curved blower wheel has fan blades having relatively small leading edge blades angles and a relatively lengthy mean camber lines. The blower wheel also comprises leading edge notches adjacent its blower wheel inlet. The leading edge notches eliminate buffeting that would occur with such blades if such notches were not present.