Turbine Stator Vane Insert for Stress Reduction
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Solution Overview
Problem
Prior stator designs for turbine engine compressors suffer from high mechanical and vibrational stresses at the leading and trailing edges of vanes, leading to potential damage or breakage due to inadequate stress distribution and damping.
Innovation Solution
Incorporation of an abutment-forming insert within the outer shroud cavity, which acts as a rigid spacer between radially-inner and -outer tongues, allowing for controlled micromovements and modifying vibratory behavior to reduce stress and prevent resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the leading and trailing edges of the vanes are connected to very thick and stiff portions of the outer shroud, then the structural strength is improved, but the mechanical stresses and vibrational damage risk at the connection zones increases
Solution Approach 1:
The patent applies local quality by creating zones of different stiffness within the outer shroud. The mounting tabs remain stiff for structural support, while the leading and trailing edge connection zones are designed with reduced stiffness to distribute stresses more evenly and reduce vibrational damage risk.
Solution Approach 2:
The outer shroud is segmented into distinct functional zones: stiff mounting tab portions for structural support and reduced-stiffness connection portions for stress distribution. This segmentation allows each zone to perform its specific function optimally without compromising the entire structure.
2Stress or pressure
If the leading and trailing edges of the vanes are connected to less rigid zones of the outer shroud, then the stress distribution is improved, but the damping of vibrational movements at the connection zones is insufficient
Solution Approach 1:
The patent introduces an intermediary element (such as a damping insert or viscoelastic material) between the vane connection zone and the outer shroud. This intermediary provides both stress distribution and vibrational damping, resolving the contradiction between reduced stiffness for stress distribution and sufficient damping for reliability.
3Stability of the object's composition
If the outer shroud is made thicker and stiffer to reduce vibrational movements, then the structural stability is improved, but the weight and complexity of the stator sector increases
Solution Approach 1:
Instead of making the entire outer shroud thicker and stiffer, the patent applies local quality by concentrating additional stiffness and damping properties only in specific zones where they are needed - namely the mounting tab areas and the connection zones - while keeping the rest of the shroud lighter and simpler.
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 limits mechanical stresses on the vanes, reducing the risk of breakage from vibrational fatigue and allowing for easy monitoring and maintenance of the outer shroud.
Implementation Method 1
said abutment-forming insert being suitable for limiting the radial movements of the radially-inner tongue by contact and thus for modifying the vibratory behavior of said radially-inner tongue
Data Source
AI summary
A stator angular sector for a turbine engine compressor and including: an outer shroud and an inner shroud; and at least one vane extending radially between the shrouds and connected thereto at its radial ends. At one of its axial ends the outer shroud includes a cavity opening out to the axial end and extending between a radially-inner tongue of the outer shroud to which the radially-outer end of the vane is connected and a radially-outer tongue of the outer shroud carrying a mounting mechanism for mounting the stator angular sector to a casing of the engine. An abutment-forming insert is housed at least in part in the cavity, the abutment-forming insert configured to limit radial movements of the radially-inner tongue by contact and thus to modify vibratory behavior of the radially-inner tongue.