Axial Fan Hub with Recessed Diffuser for Static Pressure Recovery
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Solution Overview
Problem
In turbomachinery, axial fan assemblies face dynamic pressure losses and 'hub dead water' issues, which reduce static pressure recovery and efficiency, and existing solutions like guide vanes and diffusers either fail to address backflow or increase system size.
Innovation Solution
An axial fan assembly with a hub having an upstream portion to accelerate fluid flow and a downstream recess configured to diffuse fluid flow, combined with recirculation channels that guide and swirl recirculating flow to convert dynamic pressure into static pressure, reducing backflow and enhancing static efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If guide vanes are disposed downstream of the impeller to redirect circumferentially rotating flow, then static pressure recovery is improved, but system size increases and backflow is not reduced
Solution Approach 1:
The patent combines the guide vane hub with a diffuser structure, merging two separate components into a single integrated hub assembly. The diffuser portion extends axially from the hub and works in conjunction with the guide vanes to redirect flow and reduce backflow, achieving static pressure recovery without requiring additional separate diffuser components that would increase system size.
Solution Approach 2:
The diffuser portion acts as an intermediary element between the guide vanes and the outlet. It receives the flow redirected by the guide vanes and further converts the circumferentially rotating flow into axial flow, reducing backflow and enhancing static pressure recovery before the flow exits the system.
2Stress or pressure
If diffusers are added to decrease velocity and increase uniformity of outlet flow, then static pressure recovery is improved, but system size increases and backflow is not reduced
Solution Approach 1:
The diffuser is integrated into the hub structure itself, forming a unified hub assembly that includes both the guide vane support function and the diffuser function. This merging eliminates the need for separate diffuser components and reduces overall system complexity while maintaining the ability to convert dynamic pressure to static pressure.
3Stability of the object's composition
If hub dead water is present causing back flow, then flow uniformity is reduced, but adding components to address backflow increases system size
Solution Approach 1:
The hub structure itself provides the diffuser function to address backflow and hub dead water issues. By incorporating the diffuser portion into the hub, the system uses its existing structural elements to eliminate the harmful recirculating flow pattern without requiring additional separate components that would increase system size.
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 effectively reduces hub dead water and improves static pressure recovery, achieving higher static efficiency without the need for large diffusers, as demonstrated by improved fan performance in static pressure conversion and flow characteristics.
Implementation Method 1
The upstream portion of the hub is configured to accelerate the flow of fluid towards an outer circumference of the hub
Implementation Method 2
a downstream portion having a recess extending axially into the hub, the downstream portion being configured to diffuse a flow of fluid downstream of the hub
Implementation Method 3
recirculation channels that guide and swirl recirculating flow to convert dynamic pressure into static pressure, reducing backflow and enhancing static efficiency
Data Source
AI summary
A diffuser and method of diffusing a working fluid is disclosed. The assembly includes a shroud, and a hub disposed within the shroud. The hub includes an upstream portion, a downstream portion having a recess extending axially into the hub, the hub being configured to diffuse a flow of fluid downstream of the hub.