Compressor Disk Blade Lock Assembly for Stress Reduction
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Solution Overview
Problem
Turbine engine rotor disks experience fatigue and stress concentration issues due to thermal cycles, leading to potential cracking at loading and locking slots, which are prone to failure under compressive and tensile forces.
Innovation Solution
A blade loading and locking system that eliminates the need for traditional loading and locking slots by using a lock assembly with a dovetail and slider seals to secure blades onto the disk, allowing for 90-degree rotation and interference within the blade slot to prevent removal, with additional slider seals and spacer seals to manage slack and prevent air leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional loading and locking slots are used in the rotor disk, then blades can be assembled and secured to the disk, but stress concentrations occur at the slots leading to fatigue and potential cracking under thermal cycles
Solution Approach 1:
The patent removes the traditional loading and locking slots from the rotor disk by extracting this function to a separate lock assembly. The lock assembly is inserted into a simple blade slot, and the locking mechanism is taken out of the disk structure itself, eliminating the stress-concentrating slots from the critical rotating component.
Solution Approach 2:
The lock assembly serves as an intermediary component that mediates between the blade and the rotor disk. Instead of the blade directly interacting with the disk through slots, the lock assembly is inserted into the blade slot and engages with the blade's dovetail, providing the loading and locking functions without requiring slots in the disk.
2Reliability
If loading and locking slots are eliminated from the rotor disk, then stress concentrations are reduced and durability is improved, but a new assembly mechanism is required to secure blades to the disk
Solution Approach 1:
The blade assembly system is segmented into distinct functional components: the blade slot in the disk, the lock assembly with its set screw and locking features, and the blade itself with its dovetail. This segmentation allows the complex locking function to be isolated in a separate assembly unit rather than being integrated into the disk structure.
Solution Approach 2:
The lock assembly is pre-positioned in the blade slot before the blade is fully installed. The set screw is preliminarily positioned to engage with the blade's dovetail, and the locking features are prepared in advance, allowing for a streamlined assembly process where components are sequentially engaged without requiring complex in-situ adjustments.
3Stability of the object's composition
If the lock assembly uses a set screw to engage with the blade slot depression, then rotation of the lock assembly is prevented, but additional assembly steps are required to tighten and secure the connection
Solution Approach 1:
The lock assembly utilizes asymmetric geometry where the set screw has a rounded end that fits into a specifically shaped depression in the blade slot. This asymmetric interface provides inherent anti-rotation capability, as the curved surfaces can only engage in one orientation, preventing the lock assembly from rotating once assembled.
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 enhances the durability of rotor disks by reducing stress concentrations and preventing blade movement, while maintaining efficient assembly and operation by minimizing the number of seals and maintaining structural integrity under thermal cycles.
Implementation Method 1
The dovetail interferes with the blade slot to prevent removal of the blade from the blade slot
Implementation Method 2
Slider seals are then inserted on each side of the blade slot, between the blade and the disk to limit air from entering the blade slot
Implementation Method 3
a spacer seal is placed across the blade slot at the location of each lock assembly to take up the slack
Implementation Method 4
The lock assemblies can be moved from the released position, to a locked position. A set screw on each lock assembly is tightened to move the lock assembly into the lock position
Data Source
Figure 1
Figure 2~3
Figure 4~6
AI summary
A compressor disk (26) for a turbine engine includes a plurality of blades (28) mounted about the circumference. To assemble the blades (28) onto the disk (26) a lock assembly (46) is inserted within a blade slot (36) on the disk (26). A blade (28) is assembled into the blade slot (36) and slider seals (40) are inserted between the blade (28) and the disk (26) to limit air from entering the blade slot (36). Additional blades (28) are assembled until the end of the slider seals (40) are reached. The process is repeated until all the blades (28) have been assembled onto the disk (26). After the last blade (28) has been assembled a spacer seal (54) is placed at each lock assembly (46) to take up the slack. Once all the blades (28) and spacer seals (54) are assembled the lock assemblies (46) can be moved to a locked position.