Angled Pin Fastening for Turbomachine Stator Shrouds
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Solution Overview
Problem
Conventional fastening systems for turbomachine stator shrouds are inefficient as the number of vanes increases, leaving less space for fastening arrangements, necessitating an improved method for securing shroud portions around stator vane assemblies.
Innovation Solution
A shroud design featuring pin holes in two portions that are angled relative to the axial turbomachine direction, allowing pins to be inserted and press-fitted for secure assembly, with the pins made of material with equal or greater thermal expansion to prevent slippage, enabling secure and thermally stable attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fastening systems are used with increasing number of vanes, then sealing and gas path efficiency are improved, but available space for fastening arrangements decreases
Solution Approach 1:
The pin holes are oriented at an angle relative to the axial direction, transitioning from a conventional axial fastening approach to an angled configuration. This dimensional change in hole orientation allows the fastening system to utilize previously unavailable spatial dimensions, enabling secure attachment while accommodating higher vane counts with reduced circumferential spacing.
2Area of stationary object
If pin holes are oriented at an angle relative to axial direction, then space efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The shroud is divided into two separate portions that are joined together using the angled pin holes. This segmentation allows each portion to be manufactured independently with standard drilling and tapping operations, avoiding the need for complex angled hole machining in a single monolithic structure. The modular approach simplifies manufacturing while achieving the space-efficient angled configuration.
3Reliability
If pins are made of material with equal or greater thermal expansion, then thermal stability is improved, but pin slippage risk increases
Solution Approach 1:
The pin material is specifically selected to have equal or greater thermal expansion coefficient than the shroud portions. As the assembly heats up during operation, the pin expands more than or equal to the surrounding material, maintaining constant contact pressure and preventing slippage. This thermal expansion matching ensures the pin remains securely retained throughout the thermal cycle.
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 provides a secure, thermally stable, and space-efficient assembly method for turbomachine stator shrouds, offering simplified assembly, reduced size, and lighter weight while maintaining structural integrity under thermal expansion.
Implementation Method 1
The pin can be made of a material with equal or greater thermal expansion than the first and second portions such that the pin is prevented from slipping out of the first and second pin holes when heated.
Data Source
AI summary
A shroud for a turbomachine stator includes a first portion and a second portion configured to sandwich around at least a portion of a stator vane assembly, a first pin hole defined in the first portion at an angle relative to an axial direction of the turbomachine, and a second pin hole defined in the second portion at the angle of the first portion, wherein the first pin hole is aligned and in communication with the second pin hole to accommodate a pin configured to be seated in the first and second pin holes.