Hydrostatic Seal Shoe and Rail Structure for Low-Leakage Durability
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Solution Overview
Problem
Current hydrostatic seal assemblies in gas turbine engines face challenges in maintaining durability and efficiency due to wear and friction, particularly in adjusting to varying engine operating conditions and pressure differentials, which affects the seal's ability to minimize leakage and maintain optimal gap dimensions.
Innovation Solution
The implementation of a hydrostatic seal assembly with a shoe and rail design, where the shoe has a reduced radial height and a notch for the rail, allowing the rail to provide additional support and sealing, reducing the overall mass of the shoe and increasing its natural frequency to prevent premature failure, while the rail's different material reduces friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shoe structure is made robust to withstand pressure differentials and wear, then durability is improved, but mass increases and natural frequency decreases leading to premature failure
Solution Approach 1:
The shoe structure is segmented into two distinct components: the shoe body and the rail. The rail is a separate element that can be attached to or integrated with the shoe, allowing independent optimization of each component. This segmentation enables the shoe to be lighter while the rail provides the necessary structural support and wear resistance, resolving the contradiction between durability and mass.
Solution Approach 2:
The invention employs composite construction where the rail (made from wear-resistant material) is combined with the shoe structure. This composite approach allows the shoe to achieve required durability through the rail's wear resistance without increasing the shoe's base mass, as the rail serves as a protective and structural add-on component.
2Reliability
If the shoe mass is reduced to increase natural frequency and prevent premature failure, then reliability is improved, but structural support and sealing capability deteriorate
Solution Approach 1:
By separating the shoe into a lightweight shoe body and a separate rail component, the structural support function is assigned to the rail while the shoe body remains light. The rail provides the necessary strength and structural support for withstanding pressure differentials, while the shoe body maintains low mass for high natural frequency, thus resolving the contradiction between reliability and structural support.
Solution Approach 2:
The rail is positioned specifically at the interface with the secondary seal where structural support and sealing capability are most critical. This localized reinforcement provides strength exactly where needed without adding mass throughout the entire shoe structure, allowing the shoe to remain lightweight while maintaining adequate structural support at critical locations.
3Ease of manufacture
If the shoe structure is simplified to reduce complexity, then ease of manufacture is improved, but adaptability to varying engine operating conditions deteriorates
Solution Approach 1:
The rail-shoe assembly is designed to be radially movable, allowing dynamic adjustment of the seal gap in response to varying engine operating conditions and pressure differentials. This dynamic capability is achieved through a relatively simple structural arrangement where the rail can move radially on the shoe, providing adaptability without significant structural complexity.
Solution Approach 2:
The segmented design with the rail as a separate component allows independent optimization of manufacturing simplicity and adaptability. The shoe body can be manufactured as a simple base structure, while the rail provides the adaptive sealing surface that can move radially. This segmentation enables each component to be manufactured separately with simpler processes while the assembled structure achieves the required adaptability.
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 enhances the durability and efficiency of the seal assembly by reducing mass, increasing natural frequency, and allowing for better adjustment to pressure differentials, thereby minimizing leakage and extending operational life.
Implementation Method 1
A radially movable hydrostatic low leakage seal positioned between relative moving parts may be provided to adjust and maintain the desired gap dependent on engine operating conditions
Implementation Method 2
the rail's different material reduces friction and wear
Data Source
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AI summary
A hydrostatic seal assembly (62) for a gas turbine engine (20) includes a shoe (68) movable radially relative to a longitudinal engine axis (A). At least one beam (74) supports radial movement of the shoe (68). A secondary seal (76) is fixed relative to the shoe (68). A rail (78; 110) is attached to the shoe (68) and in sealing engagement with the secondary seal (76). A gas turbine engine (20) and a method of creating a seal with a hydrostatic seal (62) are also disclosed.