APU Support Tube Anti-Vortex Shedding Design
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Solution Overview
Problem
Gas turbine engines, particularly aircraft auxiliary power unit (APU) turbine engines, face noise challenges due to vortex shedding and swirl effects caused by aerodynamic struts, which are not effectively mitigated by existing noise attenuation systems.
Innovation Solution
The implementation of a passive anti-vortex shedding apparatus with tubular support members and flow-modifying structures, such as discrete elliptical elements or helically wrapped strakes, positioned on the exterior of support tubes to reduce vortex shedding and straighten exhaust flows, thereby minimizing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If aerodynamic struts with separate lubricant conduits are used, then structural support and lubrication are provided, but noise is generated by vortex shedding
Solution Approach 1:
The patent combines the support tube and lubricant conduit into a single integrated tubular support member. The lubricant conduit is formed within the wall structure of the support tube itself, eliminating the need for separate conduits and reducing overall structural complexity while maintaining both support and lubrication functions
Solution Approach 2:
The patent introduces flow-modifying structures (such as vortex generators or strakes) as intermediary elements attached to the exterior surface of the tubular support members. These intermediaries alter the fluid flow pattern around the support tubes to reduce vortex shedding and associated noise without compromising the structural support function
2Weight of moving object
If traditional aerodynamic struts are used, then mounting support is provided, but weight is increased
Solution Approach 1:
By merging the support and lubrication functions into a single tubular structure, the patent eliminates redundant materials and manufacturing steps associated with assembling separate struts and conduits, thereby reducing overall weight while maintaining structural reliability
Solution Approach 2:
The patent optimizes the geometric parameters of the tubular support members, including wall thickness, diameter, and the configuration of flow-modifying structures, to achieve the lightest possible weight that still provides adequate structural support and reliable lubrication delivery
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 solution reduces noise levels by minimizing pressure pulses, swirl angles, and shear effects, while also offering weight reduction over traditional aerodynamic struts with separate lubricant conduits, enhancing the efficiency of noise attenuation in APU exhaust systems.
Implementation Method 1
reduce vortex shedding of a passing fluid
Implementation Method 2
straighten exhaust flows
Data Source
AI summary
An assembly for use with a power-producing unit includes an annular case, a hub positioned radially inward of the case, a fluidic flow path defined between the case and the hub, a plurality of support tubes each extending between the case and the hub, and a flow modifying structure positioned on an exterior surface of at least a first one of the support tubes and configured to reduce vortex shedding of a passing fluid.