Transition Duct Assembly With Clearance Gaps For Thermal Expansion

Solution Overview

Problem

The connection of off-axis transition ducts in turbomachines to turbine sections is prone to thermal expansion, causing stresses and potential failure due to undesirable shifts, which existing designs fail to adequately address.

Innovation Solution

The implementation of a turbomachine design featuring a plurality of transition ducts in an annular array with offset outlets, supported by a ring assembly with varying bore hole and mating bore hole gaps to accommodate thermal expansion, and connected using mechanical fasteners that allow for movement along radial and tangential axes, thereby mitigating stress and strain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If off-axis transition ducts are used to shift hot gas flow radially and tangentially, then first stage nozzles can be eliminated and efficiency increases, but thermal expansion causes undesirable shifts and stresses that may lead to duct failure

Engineering Contradiction:

Improvepower outputVSAvoidduct connection stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The connection assembly is designed to be dynamic rather than rigid, allowing the transition duct to move relative to the stationary component during thermal expansion. The mechanical fasteners with clearance holes enable the duct to shift position while maintaining connection, accommodating thermal growth without causing failure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The design changes the geometric parameters of the connection, specifically providing clearance between the fastener and the bore hole walls. This parameter change allows for movement in radial and tangential directions, transforming the connection from a fixed-position joint to one that accommodates dimensional changes due to thermal expansion.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If the duct outlet is offset from the inlet along longitudinal and tangential axes, then flow shifting function is achieved, but thermal expansion causes increased stresses and strains within the duct

Engineering Contradiction:

Improveflow direction controlVSAvoidduct structural integrity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The mechanical fastener system acts as an intermediary between the transition duct and the stationary component. Rather than directly constraining the duct, the fasteners with clearance holes provide a buffered connection that allows thermal expansion while maintaining attachment, reducing stress concentration on the duct structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If rigid connection is used to secure transition duct to support ring assembly, then structural stability is improved, but thermal expansion causes stresses and potential failure

Engineering Contradiction:

Improveconnection stabilityVSAvoidduct failure resistance

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The connection assembly is designed to be dynamic rather than rigid, allowing the transition duct to move relative to the stationary component during thermal expansion. The mechanical fasteners with clearance holes enable the duct to shift position while maintaining connection, accommodating thermal growth without causing failure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The design changes the geometric parameters of the connection, specifically providing clearance between the fastener and the bore hole walls. This parameter change allows for movement in radial and tangential directions, transforming the connection from a fixed-position joint to one that accommodates dimensional changes due to thermal expansion.

Inventive Principle:

Principle #35Parameter changes

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 design effectively manages thermal expansion, reducing the risk of duct failure and maintaining structural integrity while eliminating the need for first stage nozzles, thereby increasing efficiency and power output.

Implementation Method 1

thermal expansion of the ducts can cause undesirable shifts in the ducts along or about various axes

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10260360B2Transition duct assembly

Publication Date: 2019.04.16 GE INFRASTRUCTURE TECH LLC

AI summary

A turbomachine includes a plurality of transition ducts and a support ring assembly. The outlet of a transition duct includes an inner flange and an outer flange. The turbomachine includes bore holes defined in the inner flange and outer flange, mating bore holes defined in the support ring assembly, and mechanical fasteners connecting the inner flange and the outer flange to the support ring assembly. A first one of the bore holes or mating bore holes has a first maximum radial gap and a first maximum tangential gap relative to an associated mechanical fastener. A second one of the bore holes or mating bore holes has a second maximum radial gap and a second maximum tangential gap relative to an associated mechanical fastener. The second maximum radial gap is greater than the first maximum radial gap or the second maximum tangential gap is greater than the first maximum tangential gap.