Gas Turbine Surge Bumper Assembly Design

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Solution Overview

Problem

Gas turbine engines face challenges in accurately controlling the position of variable guide vanes due to excessive radial deflections of synchronizing rings during surge conditions, leading to stress issues beyond the yield strength of typical composite bumpers.

Innovation Solution

A surge bumper assembly is introduced, comprising a bracket and a composite pad connected by rivets, which is disposed adjacent a split in the synchronizing ring and extends axially to contact the engine case, minimizing excessive radial deflection and providing precise alignment and reduced stress on the synchronizing ring assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If typical composite bumpers mounted on the inner diameter of the synchronizing ring are used to limit radial deflection, then the synchronizing ring stiffness is increased, but under surge conditions the deflections still exceed the yield strength of the synchronizing ring and splice brackets

Engineering Contradiction:

Improvesynchronizing ring stiffnessVSAvoidability to control vane position accurately

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The bumper assembly is divided into separate components: a bracket attached to the synchronizing ring and a pad attached to the bracket. This segmentation allows each component to be optimized independently for its specific function, with the bracket providing structural attachment and the pad providing the necessary compliance to absorb surge energy without exceeding yield strength.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The pad is made from a compliant material that provides both structural support and energy absorption capability. This composite approach allows the bumper assembly to withstand surge loads without causing excessive deflection or stress in the synchronizing ring and splice brackets, while maintaining the stiffness needed for normal operation.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If adjustable composite bumpers are used to limit radial deflection during normal operation, then the synchronizing ring deflection is reduced, but the constrained space in gas turbine engines prevents accommodation of typical composite bumper designs

Engineering Contradiction:

Improvesynchronizing ring deflection controlVSAvoidspace required for bumper assembly

Core Design Contradiction:

Stability of the object's compositionVSVolume of moving object

Solution Approach 1:

The pad is attached to the bracket such that it extends axially adjacent to the inner radial surface of the synchronizing ring, nesting the bumper assembly within the existing structural envelope. This nested configuration allows the bumper to provide deflection control without requiring additional radial space that would interfere with other engine components.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

Instead of increasing radial thickness to accommodate a larger bumper, the design extends the bumper assembly axially along the length of the synchronizing ring. This dimensional transition from radial to axial direction allows the bumper to fit within the constrained radial space while maintaining sufficient size to absorb surge energy.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Manufacturing precision

If high synchronizing ring stiffness is used to control deflection, then the vane position control is improved, but stresses exceeding yield strength occur during surge conditions

Engineering Contradiction:

Improvevane position control precisionVSAvoidstress capacity during surge

Core Design Contradiction:

Manufacturing precisionVSStrength

Solution Approach 1:

The compliant pad is positioned in advance to contact the engine case during surge conditions, providing cushioning before excessive stresses can develop. This preemptive energy absorption prevents the synchronizing ring and splice brackets from experiencing stresses that would exceed their yield strength, while maintaining precision during normal operation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The bumper assembly changes its effective stiffness parameter based on operating conditions. During normal operation, the rigid bracket and pad provide sufficient stiffness for precision control. During surge conditions, the compliant pad deforms to absorb energy, effectively changing the system's stiffness parameter to prevent excessive stress while maintaining vane position control.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9353644B2Synchronizing ring surge bumper

Publication Date: 2016.05.31 RTX CORP

AI summary

A bumper assembly includes a bracket and a pad. The pad is connected to the bracket by a first rivet. Additionally, a synchronizing ring assembly for a gas turbine engine includes a ring section and a bumper assembly. The bumper assembly is connected to a side surface of the ring section and extends axially adjacent an inner radial surface of the ring. The bumper assembly is disposed adjacent a gap at an end of the ring section.