Hydrostatic Seal Housing Structure for Flutter Damping
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Solution Overview
Problem
Hydrostatic seals in gas turbine engines are susceptible to flutter-type events due to reinforcing forces at natural frequencies, leading to premature wear and vibration, which compromises their performance and longevity.
Innovation Solution
A hydrostatic seal design featuring a U-shaped static housing structure with a base and a shoe extending axially, where the axial length of the shoe is less than the base, and optionally includes beams coupling the shoe to the base, to improve damping characteristics and maintain seal integrity by extending the static structure to compensate for reduced shoe length, thereby reducing vibratory responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shoe axial length is reduced, then the seal is less susceptible to flutter-type events and premature wear, but the sealing effectiveness and structural support are compromised
Solution Approach 1:
The patent extends the static housing structure in the radial dimension (creating a U-shaped cross-sectional structure with segments extending radially and axially) to compensate for the reduced axial length of the shoe. This dimensional transition provides additional structural support and maintains sealing effectiveness without requiring a longer shoe, thereby resolving the contradiction between durability and length.
2Object-affected harmful factors
If the shoe axial length is reduced, then vibratory responses and flutter-type events are reduced, but the seal damping characteristics deteriorate
Solution Approach 1:
The extended static housing structure acts as an intermediary element that provides additional damping and structural support to compensate for the reduced shoe length. The U-shaped structure with its extended segments serves as a mediator between the shoe and the base, maintaining seal damping characteristics while allowing the shoe to be shorter and less susceptible to vibratory responses.
3Stability of the object's composition
If the static housing structure is extended, then the shoe can be shorter with improved damping, but the device complexity increases
Solution Approach 1:
The static housing structure is segmented into distinct functional segments: a base, a U-shaped cross-sectional structure with first and second segments extending in different directions, and an extended segment. This segmentation allows each part to serve a specific function while maintaining overall simplicity, resolving the contradiction between improved damping characteristics and device complexity.
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 design enhances aero-mechanical behavior, maintains seal damping, and allows for controlled friction and wear characteristics, improving the overall performance and lifespan of the seal by reducing unwanted vibrations and deflections.
Implementation Method 1
Hydrostatic seals involve motion of a spring-attached shoe whose response is based on 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
Implementation Method 3
EP 3290756 discloses a seal assembly for a gas turbine engine, comprising a floating non-contact seal having a base, shoe and spring
Data Source
Figure 1
Figure 2~3
AI summary
A hydrostatic seal (100) configured to be disposed between relatively rotatable components. The seal (100) includes a base (107). The seal (100) also includes a shoe (108) operatively coupled to the base (107) and extending axially from a forward end to an aft end (124) to define an axial length.