Turbine Inner Shell Support for Roundness

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Solution Overview

Problem

The existing gas turbine designs face issues with maintaining roundness and concentricity of the inner shell relative to the outer shell due to thermal expansion and torque loading, leading to inefficiencies and pinching of the inner shell between support pins, which reduces turbine performance.

Innovation Solution

The configuration includes an outer shell with brackets and an inner shell having recesses and radial projections, with pins and compliant supports that maintain specific clearances to allow differential growth and contraction, ensuring concentricity and roundness by managing torque and gravitational loads, and using arcuate contact surfaces to minimize radial force components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If support pins are used to hold the inner shell, then the inner shell is supported against gravitational loading, but the pins cause loss of roundness and concentricity when exposed to both gravitational and torque loadings

Engineering Contradiction:

Improvegravitational loading supportVSAvoidroundness and concentricity

Core Design Contradiction:

ForceVSShape

Solution Approach 1:

The support function is divided between multiple elements: support pins handle gravitational loading while arcuate contact surfaces handle torque loading. This segmentation allows each element to specialize in one type of load, preventing the concentration of multiple load types on single pins that causes deformation and loss of roundness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Arcuate contact surfaces act as intermediaries between the inner shell and the torque loading from nozzles. These surfaces provide a distributed contact area that smoothly transfers torque loads around the circumference, preventing the pinching effect that occurs when discrete pins resist torque forces.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If the inner shell is constrained to maintain roundness and concentricity, then turbine efficiency is improved, but thermal expansion and contraction cause pinching between support pins

Engineering Contradiction:

Improveturbine efficiencyVSAvoidpinching during thermal expansion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The geometry of support elements is changed from straight pins to arcuate contact surfaces. This parameter change allows the support structure to accommodate thermal expansion by providing a curved contact path that naturally absorbs dimensional changes without creating pinching forces on the inner shell.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The support system transitions from rigid pin contacts to dynamic arcuate contact surfaces that can adapt their contact points during thermal expansion and contraction. This dynamic adaptation allows the inner shell to change dimensions thermally while maintaining roundness and concentricity without pinching.

Inventive Principle:

Principle #15Dynamics

3Manufacturing precision

If clearances between pins and inner shell are reduced to maintain precision, then roundness and concentricity are improved, but thermal expansion causes binding and loss of movement freedom

Engineering Contradiction:

Improveroundness and concentricityVSAvoidthermal expansion freedom

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The contact geometry transitions from point contacts (pins) to line/surface contacts (arcuate surfaces). This dimensional change provides additional degrees of freedom for thermal expansion, as the arcuate contact can slide along its curved path rather than being constrained to a fixed pin location, accommodating thermal growth while maintaining precision.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

This configuration improves turbine efficiency by reducing the loss of roundness and concentricity, allowing for effective thermal expansion and contraction while maintaining alignment, resulting in enhanced performance by maintaining clearances and using compliant supports to counteract inertial and torque loads.

Implementation Method 1

enables thermal expansion and contraction of the inner shell relative to the outer shell in both the radial and circumferential directions

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The arcuate contact surfaces minimize radial force components

Methodology Applied

Scientific EffectForce distribution through geometry: Geometry

Data Source

PatentUS8182207B2Inner turbine shell support configuration and methods

Publication Date: 2012.05.22 GE INFRASTRUCTURE TECH LLC

AI summary

Embodiments of the present disclosure relate to a turbine which includes an outer shell, an inner shell connected to and surrounded by the outer shell in generally concentric relation therewith, at least one turbine rotor housed within the inner shell, a plurality of nozzles and shrouds carried by the inner shell, a plurality of connecting elements engaging between the inner and outer shells aligning the inner shell about the rotor, and at least one compliant support. Embodiments of the present disclosure also relates a method of configuring the securing arrangement between the inner shell and the outer shell of a turbine.