Cantilevered Hydrostatic Seal Shoe to Prevent Lock-Up and Wear
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Solution Overview
Problem
Hydrostatic seals in gas turbine engines experience friction-related issues and locking-up during high pressure differentials, leading to accelerated wear and excessive heat generation due to immobilization, especially during rotor movement.
Innovation Solution
A cantilevered hydrostatic seal design with a shoe secured at one end and free at the other, allowing for pivoting movement without a spring element, utilizing aerodynamic forces to maintain seal integrity and reduce friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-attached shoe is used in a hydrostatic seal, then the seal can maintain tight clearances across the operating range, but the friction can cause the seal to lock-up and become immobilized during high pressure differentials
Solution Approach 1:
The patent removes the spring element from the hydrostatic seal shoe, eliminating the source of friction that causes locking-up. The shoe is instead cantilevered to the seal housing, allowing it to pivot freely in response to aerodynamic forces without the harmful friction effects of a spring attachment.
Solution Approach 2:
The patent makes the shoe dynamically responsive by cantilevering it to the seal housing, allowing the shoe to pivot freely in response to changing aerodynamic forces during rotor movement. This dynamic configuration eliminates the static friction constraints imposed by spring attachment while maintaining sealing effectiveness.
2Reliability
If the hydrostatic seal maintains tight clearances during operation, then sealing performance is improved, but accelerated wear and excessive heat generation occur during maneuver operations with rotor movement
Solution Approach 1:
The cantilevered shoe configuration allows the seal to dynamically adapt to rotor movement during maneuver operations. The shoe can pivot and adjust its position in response to changing aerodynamic forces, maintaining effective sealing while reducing friction-induced wear and heat generation compared to spring-attached designs.
Solution Approach 2:
The hydrostatic seal uses the aerodynamic forces generated during operation to automatically position and adjust the shoe, eliminating the need for external spring forces. This self-adjusting mechanism maintains tight clearances and effective sealing while avoiding the friction and wear problems associated with spring attachment.
3Device complexity
If a spring element is used to attach the shoe to the seal housing, then the seal structure is complete, but the friction from the spring attachment causes the seal to lock-up during high pressure differentials
Solution Approach 1:
The patent extracts and removes the spring element from the seal structure, retaining only the essential cantilevered attachment of the shoe to the seal housing. This simplification eliminates the harmful friction and locking effects while preserving the functional completeness of the seal through the aerodynamic force-based operation.
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 cantilevered design enhances seal robustness, reduces wear, and prevents immobilization, maintaining effective sealing despite rotor movement and pressure differentials.
Implementation Method 1
aerodynamic forces developed between the seal shoe and a rotor surface during operation
Implementation Method 2
when a pressure differential is developed across the seal
Data Source
Figure 1
Figure 2~5
Figure 6~7
AI summary
A hydrostatic seal (100, 200, 300) configured to be disposed between relatively rotatable components is provided. The seal (100, 200, 300) includes a seal housing (107, 207, 307). The seal (100, 200, 300) also includes a shoe (108, 208, 308) extending axially from a forward end to an aft end to define an axial length, the shoe (108, 208, 308) cantilevered to the seal housing (107, 207, 307) at one of the forward end and the aft end, the shoe (108, 208, 308) free at the other end.