Compressor Diffuser Vane Damper for APU Vibration Control
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Solution Overview
Problem
In auxiliary power units, the secure clamping of a shroud housing over fixed radial vanes in a diffuser is challenging, leading to vibrations and potential damage due to uneven engagement, which compromises the air-tight seal and operational stability.
Innovation Solution
A damper, made of flexible polymeric material, is introduced between the shroud housing and vanes to absorb vibrations, ensuring secure engagement and preventing damage by compressing between the vanes and the shroud housing during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shroud housing is bolted to the diffuser to seal the radial vanes, then the air-tight passage is achieved, but vibrations occur between the vanes and shroud housing during operation
Solution Approach 1:
A damper is introduced as an intermediary element between the shroud housing and the radial vanes. This damper serves as a mediator that maintains the air-tight seal while simultaneously absorbing and reducing vibrations, thus resolving the contradiction between achieving a reliable seal and eliminating harmful vibrations during operation.
Solution Approach 2:
The damper is pre-installed between the shroud housing and radial vanes to provide cushioning before vibrations can cause damage. This beforehand cushioning protects the interface from vibration-induced harm while maintaining the air-tight passage, preventing the worsening of vibrations before they can affect the system.
2Reliability
If the shroud housing is secured against the vanes, then the passage is sealed, but uneven engagement causes potential damage to the vanes
Solution Approach 1:
The damper acts as an intermediary between the shroud housing and vanes, distributing the clamping load uniformly across the interface. This prevents uneven engagement that could damage the vanes while still maintaining the required seal integrity, thus protecting vane strength without compromising sealing.
Solution Approach 2:
The damper changes the mechanical parameters at the interface by providing a compliant element that distributes contact pressure evenly. This parameter change in pressure distribution prevents localized stress concentrations that would otherwise damage the vanes, while maintaining sufficient overall compression for seal integrity.
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 damper effectively reduces vibrations between the vanes and shroud housing, maintaining an air-tight seal and preventing damage to the vanes, thereby enhancing the operational stability and longevity of the auxiliary power unit.
Implementation Method 1
A damper is arranged between at least one vane and the shroud housing and configured to damp vibration of the at least one vane relative to the shroud housing during operation of the auxiliary power unit
Implementation Method 2
A damper, made of flexible polymeric material, is introduced between the shroud housing and vanes to absorb vibrations
Data Source
AI summary
An auxiliary power unit is disclosed that includes a compressor section having a compressor inlet and a compressor exit. A turbine section is arranged downstream from the compressor exit. A diffuser is disposed in fluid communication with and between the compressor section and the turbine section. The diffuser has multiple generally radially extending circumferentially arranged vanes. A shroud housing is secured against the vanes. A damper is arranged between at least one vane and the shroud housing and configured to damp vibration of the at least one vane relative to the shroud housing during operation of the auxiliary power unit.