Flow Diverter for Gas Turbine Air Separator Cooling
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Solution Overview
Problem
Conventional gas turbines experience thermal stress and cracking issues in the torque tube due to insufficient and mal-distributed cooling, leading to vibration events and forced outages, which existing solutions like relief grooves and increased thickness have failed to adequately address.
Innovation Solution
The introduction of a flow diverter for the air separator, which redirects cooling air flow from a radial to an axial direction through the use of cylindrical bodies with flow vents and a collapsible region to prevent dislodgment, ensuring effective cooling of the torque tube without requiring rotor disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is directed radially through the air separator, then cooling is provided to the torque tube, but thermal stress and cracking occur due to insufficient and mal-distributed cooling
Solution Approach 1:
The patent applies local quality by redirecting cooling air specifically to the intermediate section of the torque tube that is prone to thermal stress and cracking. The flow diverter component modifies the cooling air distribution locally at the critical area (intermediate section between forward and aft ends) rather than uniformly across the entire torque tube, providing enhanced cooling precisely where needed to prevent cracking while maintaining overall cooling effectiveness.
Solution Approach 2:
The flow diverter acts as an intermediary component between the cooling air supply system and the torque tube. It intercepts the radially flowing cooling air and redirects it axially along the torque tube, particularly toward the vulnerable intermediate section. This intermediary device modifies the cooling air flow pattern without requiring changes to the main cooling system architecture, effectively resolving the mal-distribution issue.
2Stress or pressure
If relief grooves are added to reduce thermal stress, then stress concentration is reduced, but the solution proves unsuccessful in preventing cracking
Solution Approach 1:
The patent extracts the cooling function from the general radial cooling pattern and directs it specifically to the problem area through the flow diverter. Rather than relying on geometric modifications like relief grooves that proved insufficient, the solution extracts and concentrates cooling resources at the intermediate section where thermal stress causes cracking, addressing the root cause through improved cooling distribution rather than stress redistribution.
3Strength
If the thickness of the torque tube is increased, then structural strength is improved, but the solution proves unsuccessful in preventing cracking
Solution Approach 1:
The patent changes the thermal parameter (cooling distribution) rather than the structural parameter (torque tube thickness). Instead of increasing thickness which failed to prevent cracking, the solution modifies the cooling air flow parameters - redirecting it axially to the intermediate section - thereby changing the thermal field distribution to prevent the thermal stress that causes cracking, maintaining structural integrity without additional material.
4Temperature
If direct impingement of cooling air is used, then cooling efficiency is improved, but thermal stress is exacerbated
Solution Approach 1:
The patent inverts the cooling air flow direction from radial (perpendicular to torque tube axis) to axial (parallel to torque tube axis). This inversion changes how the cooling air interacts with the torque tube surface - instead of direct impingement that creates localized thermal stress, the axial flow provides more distributed cooling along the length of the torque tube, particularly at the intermediate section, reducing thermal stress while maintaining cooling efficiency.
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 solution effectively mitigates thermal stresses and delays cracking in the torque tube, enhancing its durability and extending its operational life while minimizing downtime for maintenance.
Implementation Method 1
air flows through the open end in a radial direction and exits through the air flow vents in an axial direction
Implementation Method 2
This cooling air 72 impinges directly on the aft end 56 of the torque tube 50. It has been observed that the torque tube 50 may experience thermal stress due to the insufficient and mal-distributed cooling
Data Source
AI summary
A flow diverter for an air separator of a gas turbine includes a cylindrical body configured to fit within a cooling hole of the air separator. One or more air flow vents are defined through and around a partial circumference of the cylindrical body. A bottom panel closes the cylindrical body at one end. A mounting flange surrounds the cylindrical body at an open end and extends radially outward from the cylindrical body. When the flow diverter is installed, air flows through the open end in a radial direction and exits through the air flow vents in an axial direction. The cylindrical body may include a collapsible region that collapses to engage the air separator and prevent the flow diverter from being dislodged. The air separator may additionally or alternately include supplemental cooling holes in a recessed area proximate to its mounting flange.