Spring Biased Shroud Retention for Gas Turbine Wear Reduction
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Solution Overview
Problem
In gas turbine engines, the radial movement of components coupling the shroud due to thermal expansion can cause wear on the shroud and impact its lifespan.
Innovation Solution
A spring biased retention system is implemented, which includes a load spreader, a locator pin, a lock ring, and a biasing system with a spring arm. This system maintains contact between the load spreader and the shroud, inhibiting radial movement and distributing forces to reduce wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the shroud is coupled to the case using rigid components, then the structural strength is improved, but radial movement during thermal expansion causes wear on the shroud
Solution Approach 1:
The retention system transitions from rigid fixed components to dynamic spring-biased components that can adapt to thermal expansion. The spring arm and biasing member allow radial movement while maintaining contact force, accommodating differential thermal growth between the shroud and case without causing wear
Solution Approach 2:
The system changes the mechanical parameters of the coupling components by using spring-biased elements instead of rigid fixtures. The spring arm provides variable contact force that maintains reliability during thermal cycles, and the wear-resistant coating changes the friction parameters at the contact interface
2Manufacturing precision
If rigid coupling components are used to maintain shroud position, then positioning accuracy is improved, but thermal expansion causes relative movement and wear
Solution Approach 1:
The coupling system becomes dynamic rather than static, allowing the shroud to maintain accurate positioning while accommodating thermal expansion through controlled radial movement of the spring-biased components. The locator pin and lock ring provide precise radial positioning, while the spring arm accommodates axial thermal growth
3Reliability
If the retention system allows radial movement to accommodate thermal expansion, then wear is reduced, but contact force between components decreases
Solution Approach 1:
The spring-biased components change the force parameters by providing continuous contact force through elastic deformation. The spring arm maintains sufficient contact force to prevent excessive wear while allowing the radial movement needed for thermal expansion accommodation
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 spring biased retention system effectively reduces radial movement of components relative to the shroud, thereby minimizing wear and extending the lifespan of the shroud during gas turbine engine operation.
Implementation Method 1
a spring arm configured to apply the force to the load spreader retainer to maintain the spreader surface of the load spreader in contact with the surface of the shroud
Implementation Method 2
The locator pin defines a central cooling bore that is in fluid communication with the plenum and is configured to be coupled to a source of a cooling fluid. The spreader surface defines a plurality of impingement holes configured to direct the cooling fluid onto the surface of the shroud.
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
A system for coupling a shroud to a case associated with a gas turbine engine includes the case having a mounting pad, and the shroud having a surface that faces the case. The system includes a load spreader having a spreader surface in contact with the surface of the shroud and a locator pin coupled to the mounting pad and the load spreader to couple the shroud to the case. The system includes a load spreader retainer coupled to the load spreader. The load spreader retainer is to distribute a force to the load spreader. The system includes a biasing system coupled about the mounting pad that includes a spring arm configured to apply the force to the load spreader retainer to maintain the spreader surface of the load spreader in contact with the surface of the shroud.