Gas Turbine Vane Grommet Isolation Design
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Solution Overview
Problem
Existing gas turbine engine vane assemblies are prone to damage from foreign object impact, and the use of grommets to isolate vanes from shrouds complicates installation and airflow, leading to performance issues and the need for adhesives.
Innovation Solution
A vane assembly with a flexible grommet system where grommets are integrated into the shroud openings, forming a continuous gas path surface to secure them in place without adhesives, using flexible materials to dampen vibrations and reduce the risk of damage from foreign objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If grommets are inserted in shroud slots to isolate vane tips, then vane tip isolation from shroud is improved, but grommets can be cut by sharp vane edges during foreign object damage and damage surrounding components
Solution Approach 1:
A compliant retainer material is introduced as an intermediary between the vane tip and shroud slot. This retainer provides cushioning and compliance to prevent the sharp vane edge from cutting the grommet during foreign object impact, while still maintaining the isolating function. The retainer acts as a protective mediator that absorbs impact forces.
Solution Approach 2:
The solution uses composite construction by combining the original grommet with an additional compliant retainer material. This layered composite structure provides both the isolation function of the grommet and the protective cushioning of the retainer, creating a multi-functional assembly that addresses both isolation and impact protection needs.
2Stability of the object's composition
If adhesive is used to secure grommets in place, then grommet displacement is prevented, but installation and replacement of vanes is complicated
Solution Approach 1:
The compliant retainer is designed to be self-securing through friction and compliance with the shroud slot, eliminating the need for adhesive. The retainer's material properties allow it to grip the slot and maintain position through its own mechanical characteristics, providing self-service retention without additional fastening materials.
Solution Approach 2:
The solution changes the physical parameters of the retention system by using a compliant material with specific friction and elasticity properties. This allows the retainer to secure itself in the slot through mechanical interference and friction rather than chemical bonding, enabling easy removal and reinstallation while maintaining position stability during operation.
3Reliability
If grommets protrude to isolate vanes, then vane isolation is achieved, but airflow is disturbed and engine performance is altered
Solution Approach 1:
The compliant retainer is designed as a flexible, thin-walled structure that can deform with airflow rather than rigidly protruding into the flow path. This flexible shell design allows the retainer to maintain isolation functionality while minimizing disruption to the surrounding airflow, as the flexible material can conform to flow patterns rather than creating fixed obstructions.
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 enhances vane stability, reduces the risk of damage, simplifies installation and maintenance, and improves airflow by eliminating the need for adhesives and minimizing disruption to the engine's performance.
Implementation Method 1
each said grommet being made of a flexible material to dampen vibrations of the vane assembly
Implementation Method 2
isolate the vane extremity from the shroud ring
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A vane assembly (20) for a gas turbine engine including a shroud ring (34) with openings (54) and isolating means (28) isolating a vane extremity (24) within each opening (54), the isolating means (28) cooperating to form a continuous gas path surface (52) completely covering at least an axial portion of a surface (37) of the shroud ring (34).