Exit Guide Vane Mounting for Thermal Expansion in Gas Turbines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing bolted joint and snap connections in gas turbine engines restrict thermal expansion of exit guide vanes, leading to increased stresses and pressure losses due to flow disruption.
Innovation Solution
The exit guide vane is mounted adjacent to a diffuser assembly with connections that do not interfere with airflow, using a thrust balance seal bolted to the diffuser assembly outside of air flows, and secured by tabs and slots or lugs, allowing for thermal expansion without constraining the vane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bolted joint and snaps are used to secure the exit guide vane, then the vane is firmly attached to the diffuser assembly, but the vane is constrained from thermal expansion and airflow is disrupted causing pressure losses
Solution Approach 1:
The mounting system is segmented into three distinct components: the diffuser assembly, the thrust balance seal (which provides the bolted connection), and the exit guide vane. This segmentation allows the bolted joint to be isolated to the thrust balance seal while the vane itself remains free of direct bolted connections to the diffuser assembly, enabling thermal expansion without constraint and eliminating flow disruption from bolts in the airflow path.
Solution Approach 2:
The thrust balance seal acts as an intermediary component between the diffuser assembly and the exit guide vane. It provides the necessary bolted attachment to the diffuser assembly while creating a mounting surface for the vane that does not directly constrain thermal expansion. The intermediary structure includes slots that guide and accommodate thermal movement, mediating between the need for firm attachment and the need for thermal freedom.
2Strength
If a bolted joint and snaps are used to secure the exit guide vane, then the vane is firmly attached to the diffuser assembly, but stresses increase due to restricted thermal expansion
Solution Approach 1:
The mounting system transitions from a static rigid connection to a dynamic system that accommodates thermal movement. The slots in the thrust balance seal create a compliant mounting structure that allows the exit guide vane to move dynamically with thermal expansion while remaining attached. This dynamic capability reduces thermal stresses by allowing natural expansion rather than forcing the vane to remain in a fixed position.
Solution Approach 2:
The system changes the mounting parameters from rigid fixed-position connections to flexible slot-based connections that permit positional changes during thermal expansion. The slots provide a controlled range of motion that accommodates thermal parameter changes while maintaining attachment strength, thereby reducing stress buildup that would occur with rigid fixed-parameter mounting.
3Temperature
If tabs and slots are used to secure the exit guide vane, then the vane can expand thermally unconstrained, but the connection method must prevent rotation while allowing movement
Solution Approach 1:
The tab-slot connection employs asymmetric geometry where the tab has a specific shape that fits into the slot in only one orientation. This asymmetric design prevents rotation by ensuring that the tab cannot be inserted or rotated within the slot except in the correct angular position, while still allowing linear thermal expansion movement along the slot's length.
Solution Approach 2:
The connection is segmented into separate functional elements: tabs that provide rotational constraint and slots that provide translational freedom. This segmentation of constraints allows the system to independently control rotational stability and thermal expansion freedom, with the tab-slot interface providing rotational prevention while the slot geometry permits linear thermal movement.
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 prevents airflow disruptions and allows for unconstrained thermal expansion of the exit guide vane, reducing stress and pressure losses, while maintaining secure attachment and preventing rotation.
Implementation Method 1
the bolted joint and snaps constrains the exit guide vane from expanding thermally. This restriction of thermal expansion can undesirably increase stresses on the exit guide vane and adjoining parts
Data Source
AI summary
An example exit guide vane for a gas turbine engine is mounted adjacent to a diffuser case defining an air flow path. A thrust balance seal is attached to the diffuser and the exit guide vane is mounted adjacent the diffuser case for guiding air flow into the air flow path. The exit guide vane is mounted adjacent to the diffuser without interfering with the air flow path or restricting thermal expansion.