Variable-Stiffness Shroud Assembly for Blade Tip Rub Relief
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Solution Overview
Problem
Existing gas turbine engines experience blade tip rub issues due to insufficient clearance between rotor blades and shrouds, leading to wear and damage, which increases maintenance costs and reduces efficiency.
Innovation Solution
A compliant shroud design with variable stiffness is implemented, featuring segmented shroud arms and pads that move radially outward upon contact with rotor blades, reducing impact and minimizing blade damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid shroud design is used, then structural strength is maintained, but blade tip clearance is insufficient leading to blade damage
Solution Approach 1:
The shroud arm is designed as a compliant, flexible structure that can dynamically deflect radially outward when contacted by rotor blades. This dynamic response allows the shroud to accommodate blade tip clearance variations and prevent blade damage through controlled movement rather than rigid resistance.
Solution Approach 2:
The shroud arm's stiffness parameter is specifically engineered to be compliant rather than rigid. By changing the structural parameter from high stiffness to controlled compliance, the shroud can deflect under blade contact forces, increasing effective clearance and reducing blade tip rub while maintaining overall structural integrity.
2Reliability
If shroud pads are made compliant to reduce blade damage, then blade durability improves, but structural strength of the shroud decreases
Solution Approach 1:
The shroud is segmented into distinct components: a strong outer wall structure and compliant shroud arms with shroud pads. This segmentation allows the outer wall to maintain structural strength while the arms and pads provide compliant blade contact surfaces, resolving the contradiction between strength and compliance.
Solution Approach 2:
Different parts of the shroud have different mechanical properties. The outer wall maintains high strength and rigidity, while the shroud arms and pads are designed with controlled compliance. This local differentiation of material/structural quality allows the shroud to be strong where needed and compliant where it contacts blades.
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 design enhances durability by increasing clearance and reducing blade damage, thereby decreasing repair costs and improving engine efficiency.
Implementation Method 1
at least one of the first shroud pad or the second shroud pad to move radially outward toward the outer wall in response to a rotor blade contacting the at least one of the first shroud pad or the second shroud pad
Data Source
AI summary
Methods, apparatus, systems and articles of manufacture are disclosed. A shroud assembly of a gas turbine engine includes: a first shroud arm having a first end and a second end, the first end to couple to an outer wall and the second end to couple to a first shroud pad, and a second shroud arm having a first end and a second end, the first end to couple to the outer wall and the second end to couple to a second shroud pad, at least one of the first shroud pad or the second shroud pad to move radially outward toward the outer wall in response to a rotor blade contacting the at least one of the first shroud pad or the second shroud pad.