Turbomachine Rotor Elastic Stop Axial Retention
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Solution Overview
Problem
The existing axial retention systems in turbomachine rotors experience wear due to friction between blade roots and downstream flanges, leading to reduced service life, particularly when the turbine engine is stationary and exposed to wind, causing radial movement and subsequent friction.
Innovation Solution
An elastic stop with a U-shaped design is interposed between each blade and the downstream flange to maintain a gap and prevent friction, featuring a base with spikes for better adhesion and branches to clip the blade root, ensuring axial retention without wear during non-operation and dampening axial displacement during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the blade root rests directly on the downstream flange to ensure axial retention, then axial retention is achieved, but wear occurs on the downstream flange due to friction during radial movement
Solution Approach 1:
An elastic stop is introduced as an intermediary element between the blade root and the downstream flange. This elastic stop maintains the blade root in contact with the downstream flange during operation (ensuring axial retention) while preventing direct frictional contact during radial movement (reducing wear). The elastic material absorbs the frictional forces during slow rotation and radial displacement.
Solution Approach 2:
The solution changes the physical state and properties of the retention system by introducing an elastic material with specific mechanical properties (hardness, elasticity). The elastic stop deforms under centrifugal forces during operation to maintain contact, but yields during slow rotation to prevent wear, thus changing the retention mechanism from rigid to flexible.
2Stability of the object's composition
If elastic means are used to maintain blade roots against the downstream flange, then axial retention is improved, but frictional wear still occurs during slow rotation and radial movement
Solution Approach 1:
The elastic stop acts as a flexible element that can deform to accommodate radial movement during slow rotation. This flexibility allows the system to maintain axial retention through elastic deformation rather than rigid contact, thereby reducing frictional wear on the downstream flange during periods of slow rotation or radial displacement.
3Ease of manufacture
If the rotor is designed with axial clearance for assembly reasons, then ease of assembly is improved, but random axial positioning causes unbalance and vibrations during operation
Solution Approach 1:
The elastic stop provides self-aligning properties that allow the blade root to automatically position itself correctly during assembly. The elastic deformation and recovery of the stop guide the blade root into the correct axial position, eliminating random positioning and ensuring rotor balance without requiring precise manual positioning during assembly.
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 elastic stop effectively reduces wear by maintaining a gap between the blade and flange during non-operation and prevents friction-induced wear, while centrifugal forces during operation eliminate radial movement, thus extending the service life of the downstream flange.
Implementation Method 1
the upstream flange is equipped on its downstream face with elastic means, such as elastomer pins, intended to exert on the upstream faces of the blade roots, after assembly, sufficient forces to maintain said blade roots against the downstream flange
Implementation Method 2
the considerable centrifugal forces experienced by the blades can also cause random axial displacement of the blades within this axial clearance
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The rotor has a disk, whose periphery has a set of grooves. A set of movable fan blades (2), each having a blade root (22) housed in the grooves. A downstream flange is integrated to the disk, where each blade root comes to support on the flange. An elastic stop (8) is placed between the blade root and the downstream flange for maintaining a gap between the root and the flange, where the gap is between 0.1 and 0.8 millimeter. The stop is made of polyurethane elastomer or resin Peek(RTM: polyetheretherketone), and is adapted to clip the flange to the head.