Cooling Fan Shroud Serrations for Recirculation Control
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Solution Overview
Problem
Recirculating airflow from the downstream side to the upstream side in cooling fan modules reduces efficiency and causes unwanted noise due to pressure differences, which existing technologies fail to adequately mitigate.
Innovation Solution
The cooling fan module incorporates a shroud with axial and radial serrations on its barrel, designed to generate turbulent airflow and prevent recirculation by redirecting airflow orthogonally, thereby reducing pressure differences and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a cooling fan module uses a smooth barrel surface, then manufacturing is simple, but recirculating airflow causes efficiency loss and noise
Solution Approach 1:
The barrel surface is modified with localized serrations (axial and radial) at specific positions where airflow separation occurs, rather than changing the entire surface. This creates local turbulence zones that prevent recirculating airflow while maintaining simplicity elsewhere in the structure.
Solution Approach 2:
The serrations on the barrel surface manipulate airflow patterns by creating controlled turbulence and preventing smooth recirculating flow. The aerodynamic design of the serrations redirects air molecules to break up eddies and prevent harmful recirculation zones.
2Object-generated harmful factors
If axial and radial serrations are added to the barrel, then recirculating airflow is reduced and noise decreases, but manufacturing complexity increases
Solution Approach 1:
The serrations are divided into two distinct types (axial and radial) positioned at different locations on the barrel, each addressing specific airflow problems. This segmentation allows optimization of each serration type for its specific function while maintaining overall system effectiveness.
Solution Approach 2:
The serrations have specific geometric parameters (depth, spacing, angle) that are optimized to create the desired turbulence effect. By carefully controlling these parameters, the design achieves effective recirculation prevention without excessive manufacturing complexity.
3Ease of operation
If the fan assembly is enclosed in a shroud with opening, then airflow direction is controlled, but pressure differences cause recirculation
Solution Approach 1:
The serrated barrel surface acts as an intermediary element between the fan assembly and the external environment. It modifies the airflow emerging from the opening by creating turbulence that prevents organized recirculating patterns, thus mediating the interaction between the controlled airflow and ambient conditions.
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 increases airflow efficiency by approximately 2% and reduces overall fan noise by up to 2 dBA by effectively blocking recirculating airflow and creating turbulent flow patterns.
Implementation Method 1
The number of surface discontinuities may be collectively configured to generate turbulent airflow within the barrel to mitigate air flow from moving from the downstream side to the upstream side
Data Source
AI summary
A cooling fan module may include a fan assembly and a shroud. The fan assembly including a number of fan blades and the shroud including a first sidewall and a first ring. The first sidewall defining an opening and the first ring extending in an axial direction from the first sidewall. The first ring including an inner periphery provided with a number of first serrations, each serration of the number of first serrations extending in a radial direction. The radial direction is substantially orthogonal to the axial direction.