Hydrostatic Seal Assembly With Rail Interface for Low-Wear Turbine Sealing
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Solution Overview
Problem
Gas turbine engines face challenges in maintaining efficient sealing between rotating and stationary parts, leading to leakage and reduced durability and thermal efficiency due to wear and friction at the interface of hydrostatic low leakage seals and secondary seals.
Innovation Solution
A hydrostatic seal assembly featuring a radially movable shoe supported by beams, with a rail attached to the shoe that provides a sealing engagement with a secondary seal, allowing for reduced mass and increased natural frequency to prevent premature failure, and utilizing a different material for the rail to reduce friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hydrostatic low leakage seal is used to maintain the desired gap between rotating and stationary parts, then sealing efficiency is improved, but wear and friction at the interface with the secondary seal reduce durability
Solution Approach 1:
The seal structure is divided into two distinct components: the hydrostatic low leakage seal and the secondary seal. This segmentation allows each component to perform its specific function independently, with the secondary seal absorbing wear while the hydrostatic seal maintains the precision gap, thereby resolving the contradiction between sealing efficiency and durability
Solution Approach 2:
The secondary seal acts as an intermediary element between the hydrostatic low leakage seal and the stationary part. It provides a wear-resistant interface that protects the main sealing surface, allowing the hydrostatic seal to maintain optimal performance without suffering from wear-induced degradation
2Duration of action of stationary object
If the structure and mass of the hydrostatic low leakage seal are increased to compensate for wear and friction, then durability is improved, but natural frequency decreases leading to premature failure
Solution Approach 1:
By separating the wear-compensation function (secondary seal) from the gap-maintenance function (hydrostatic seal), the hydrostatic seal can be designed with optimized mass and structure for high natural frequency, while the secondary seal handles wear compensation without compromising the dynamic characteristics of the main sealing system
Solution Approach 2:
The secondary seal serves as a sacrificial copy or substitute for the wear interface, allowing the hydrostatic seal to maintain its precise geometric relationship and optimal mass properties while the secondary seal absorbs the wear effects
3Duration of action of stationary object
If a fixed secondary seal is provided relative to the moving hydrostatic seal, then wear compensation is improved, but friction at the interface reduces thermal efficiency
Solution Approach 1:
The secondary seal is designed as a thin, flexible element that can deform to accommodate relative motion between the rotating and stationary parts. This flexibility reduces friction and allows for smoother operation, thereby improving thermal efficiency while still providing wear compensation functionality
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 solution enhances the durability and thermal efficiency of gas turbine engines by reducing leakage, increasing the natural frequency of the seal system, and extending the operational life through improved sealing and reduced wear, while allowing for more compact packaging and easier maintenance.
Implementation Method 1
A rail is attached to the shoe and is in sealing engagement with the secondary seal
Implementation Method 2
A radially movable hydrostatic low leakage seal positioned between relative moving parts may be provided to adjust and maintain the desired gap
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.