Turbomachine Compressor Ring Sector Locking
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Solution Overview
Problem
The existing turbomachine designs experience increased stress and reduced service life due to radial temperature gradients causing 'straightening' of ring sectors, which leads to increased curvature and stress concentration in locking mechanisms.
Innovation Solution
The turbomachine design employs C-shaped elastic locks engaged only on the end portions of ring sectors and the casing rail, allowing the middle parts of the ring sectors to move radially freely, reducing stress on the locks and using fewer, narrower locks that are circumferentially spaced, with optional circumferential locking systems for additional immobilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If locks are arranged circumferentially end to end forming continuous annular locking means, then radial immobilization of ring sectors is secure, but mass of locking system increases and service life reduces due to stress concentration
Solution Approach 1:
The continuous annular locking system is segmented into discrete locks spaced circumferentially apart. Each lock engages only with the end portions of ring sectors rather than forming a continuous 360° locking means. This segmentation reduces stress concentration in individual locks while maintaining sufficient radial immobilization security through the distributed arrangement of multiple locks around the circumference.
Solution Approach 2:
The locking system transitions from uniform continuous engagement to localized engagement at specific circumferential positions. Locks are positioned to engage only with end portions of ring sectors, creating localized locking zones rather than continuous engagement. This local quality approach allows the middle parts of ring sectors to move freely while end portions remain securely locked, reducing overall stress in the locking system.
2Force
If locks have width equal to ring sector width for full engagement, then radial holding is maximized, but stress concentration in middle part of locks increases due to temperature gradients
Solution Approach 1:
The engagement zone of each lock is segmented to cover only the end portions of ring sectors rather than the full width. This creates discrete engagement zones at the ends of ring sectors, avoiding stress concentration in the middle parts of locks that would result from full-width engagement. The segmented engagement maintains sufficient radial holding force through the cumulative effect of multiple locks.
Solution Approach 2:
The locking engagement is made non-uniform with respect to the ring sector width. Locks engage locally at the end portions of ring sectors rather than uniformly across the full width. This local quality differentiation allows the middle parts of ring sectors to accommodate thermal expansion and contraction freely, reducing stress concentration in the locks while maintaining adequate radial holding force at the engaged end portions.
3Stability of the object's composition
If continuous annular locking means are used over 360°, then complete radial constraint is achieved, but mass of locking system increases
Solution Approach 1:
The continuous 360° annular locking system is replaced by a segmented arrangement of discrete locks spaced circumferentially apart. Each lock has a width less than the ring sector width, creating gaps between locking zones. This segmentation significantly reduces the mass of the locking system while maintaining sufficient radial constraint through the distributed arrangement of locks around the circumference.
Solution Approach 2:
Radial constraint is applied locally at the end portions of ring sectors rather than uniformly across the entire circumference. The locking system provides localized constraint zones at discrete circumferential positions, allowing the middle parts of ring sectors to move freely in the radial direction. This local quality approach maintains adequate overall radial constraint while minimizing locking system mass by eliminating material in the non-engaged regions.
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 reduces stress on locking mechanisms, extends their service life, and minimizes mass while maintaining secure radial immobilization of ring sectors, even under temperature gradients.
Implementation Method 1
an elastic latch with a substantially C-section, which is engaged axially on the casing rail and on the circumferential rim of the ring sector
Implementation Method 2
there appears a relatively large temperature gradient in the radial direction in each ring sector, which leads to a 'straightening' of this ring sector. This phenomenon essentially results in an increase in the radius of curvature of the ring sector
Data Source
Figure 1~3
Figure 4~6
AI summary
Turbine or turbomachine compressor stage, comprising a blade wheel surrounded by a sectored ring carried by a casing, each ring sector (22) comprising a circumferential rim (34) radially clamped on a casing rail by two C-section locks (240) which are engaged on the circumferential end portions of the rim of that ring sector and on corresponding portions of the casing rail.