Segmented Auxiliary Struts for Turbine Exhaust Rotating Stall

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Solution Overview

Problem

Gas turbine engines are susceptible to rotating stall conditions during low-flow operating conditions, which cause asynchronous high cycle fatigue on turbine blades due to the formation of rotating stall cells.

Innovation Solution

The implementation of segmented auxiliary struts and flow control vanes in the turbine exhaust section, which can rotate to angled positions to block reverse flows and mitigate the formation of rotating stall cells by reducing the velocity gradient of the shear layer adjacent the last stage blades.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the gas turbine engine operates in low-flow operating conditions, then the engine can operate at part-load or transient conditions, but rotating stall cells form causing asynchronous high cycle fatigue on turbine blades

Engineering Contradiction:

Improveoperating conditionsVSAvoidturbine blade fatigue

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The exhaust section is divided into multiple compartments by introducing auxiliary struts that segment the flow path. This segmentation prevents the formation of large rotating stall cells by creating smaller, more manageable flow regions, thereby reducing the harmful asynchronous high cycle fatigue on turbine blades while allowing the engine to operate in low-flow conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Auxiliary struts are introduced as intermediary elements between the turbine blades and the exhaust wall. These struts act as mediators that modify the flow characteristics by increasing the tangential velocity of reverse flows and minimizing the velocity gradient in the shear layer, thereby preventing rotating stall formation while maintaining adaptability to low-flow operating conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If auxiliary struts are added to mitigate rotating stall, then the velocity gradient is reduced and rotating stall cells are prevented, but the device complexity increases

Engineering Contradiction:

Improverotating stall mitigationVSAvoidexhaust section structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary struts are designed with rotational capability, allowing them to adjust their position dynamically. The inner and outer portions of the auxiliary struts can rotate to angled positions as needed, providing adaptability to different operating conditions while maintaining a relatively simple structural implementation compared to fully movable complex systems.

Inventive Principle:

Principle #15Dynamics

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 solution effectively reduces the likelihood of rotating stall formation by increasing the tangential velocity of reverse flows and minimizing the velocity gradient, thereby protecting turbine blades from high cycle fatigue.

Implementation Method 1

The auxiliary strut is segmented and includes an inner portion, a central portion disposed radially outward from the inner portion, and an outer portion disposed radially outward from the central portion. The inner portion, the outer portion, or both are configured to rotate to an angled position.

Methodology Applied

Scientific EffectFluid flow control:

Implementation Method 2

mitigate the formation of rotating stall cells by reducing the velocity gradient of the shear layer adjacent the last stage blades

Methodology Applied

Scientific EffectShear layer velocity gradient reduction:

Data Source

PatentUS12428973B2Mitigation of rotating stall in turbine exhaust section using segmented auxiliary struts

Publication Date: 2025.09.30 GE INFRASTRUCTURE TECH LLC

AI summary

A system includes a turbine exhaust section having an exhaust flow path, an inner exhaust wall radially disposed along the exhaust flow path, and an outer exhaust wall radially disposed along the exhaust flow path and radially outward from the inner exhaust wall. The turbine exhaust section includes an auxiliary strut extending from the inner exhaust wall to the outer exhaust wall. The auxiliary strut is segmented and includes an inner portion, a central portion disposed radially outward from the inner portion, and an outer portion disposed radially outward from the central portion. The inner portion, the outer portion, or both are configured to rotate to an angled position. The auxiliary strut is circumferentially disposed between adjacent struts of the turbine exhaust section.