Embedded Steam Turbine Fin Locking for High-Temperature Sealing
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Solution Overview
Problem
Steam turbine rotors with embedded fins face challenges in maintaining sealing performance due to low drawing strength, especially under high temperatures and large rotor shaft diameters, which can lead to fin disengagement and leakage.
Innovation Solution
The embedded fin is enhanced by forming an L-shaped structure from a metal sheet, segmented into multiple tiers and fixed with a locking strip, and surface roughening techniques are applied to increase static friction coefficients, ensuring better adhesion and drawing strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an embedded fin is used in the steam turbine rotor, then the sealing performance can be maintained and the fin is replaceable, but the drawing strength of the fin is insufficient under high centrifugal force
Solution Approach 1:
The embedded fin is divided into multiple tiers along the circumferential direction, with each tier having locking protrusions that engage with corresponding grooves in the rotor. This segmentation allows the fin to be fixed at multiple points, distributing the centrifugal force across several locking interfaces and preventing disengagement even under high-speed rotation.
Solution Approach 2:
The embedded fin is nested within a groove formed in the rotor, with the fin's bottom surface fitting into the groove and locking protrusions extending into locking grooves. This nested configuration ensures the fin remains securely positioned within the rotor structure while maintaining replaceability.
2Power
If the rotor diameter is increased to meet power demand, then the power output increases, but the centrifugal force acting on the embedded fin increases, reducing drawing strength
Solution Approach 1:
By dividing the fin into multiple tiers with intermediate locking positions, the centrifugal force acting on each individual tier is reduced compared to a single large fin. Each tier locks independently at its own groove, creating multiple anchor points that distribute the stress across the entire fin structure, enabling the rotor to achieve larger diameters without compromising fin retention.
Solution Approach 2:
The locking mechanism extends into the circumferential dimension with multiple locking grooves positioned at different circumferential locations. This multi-dimensional locking approach provides redundant fixation points that prevent fin disengagement even when the rotor operates at high speeds and large diameters.
3Use of energy by moving object
If the steam temperature is increased to improve efficiency, then the thermal efficiency increases, but the thermal stress on the embedded fin increases, reducing drawing strength
Solution Approach 1:
The multi-tier structure with intermediate locking positions allows thermal expansion and stress distribution across multiple independent locking interfaces. Each tier can accommodate thermal stress independently, preventing cumulative stress concentration that would occur in a single-piece fin design, thereby maintaining drawing strength even at elevated steam temperatures.
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 significantly enhances the drawing strength of the embedded fin, preventing steam leakage and improving the reliability of the steam turbine by maintaining sealing performance even under increased temperature and rotor diameter conditions.
Implementation Method 1
the embedded fin is fixed in a groove formed in the rotor
Implementation Method 2
surface roughening techniques are applied to increase static friction coefficients, ensuring better adhesion and drawing strength
Data Source
Figure 1~2
Figure 3
AI summary
According to the present invention, the steam turbine rotor includes an embedded fin which includes: a bent bottom part; and an upright part including a fin tip and a fin root, and which is inserted in a fixing groove and fixed in the fixing groove by means of a locking strip, and has an arrangement wherein a static friction coefficient between a side surface of the fixing groove and a side surface of the fin root, a static friction coefficient between a side surface of the locking strip and a side surface of the fin root, and a static friction coefficient between the side surface of the fixing groove and the side surface of the locking strip are increased.