Hydrostatic Seal Extended Housing for Flutter-Resistant Clearance Control
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Solution Overview
Problem
Hydrostatic seals in gas turbine engines are susceptible to flutter-type events due to aerodynamic forces that reinforce motion at natural frequencies, leading to premature wear and compromised seal behavior.
Innovation Solution
A hydrostatic seal design with a shoe having an axial length less than the base, coupled to a static housing structure with a U-shaped carrier extending axially forward to abut or be in close proximity to the aft end of the shoe, providing additional structural support and improved damping characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shoe axial length is extended to maintain tight clearances, then sealing performance is improved, but the seal becomes more susceptible to flutter-type events and premature wear
Solution Approach 1:
The seal structure is segmented into two distinct components: a traditional shoe portion and an extended housing portion. The extended housing (216) extends axially beyond the shoe (208) to provide additional structural support and damping without increasing the shoe's axial length, thereby maintaining sealing performance while reducing susceptibility to flutter-type events.
Solution Approach 2:
The extended housing acts as an intermediary structural element that provides additional damping and support. It mediates between the shoe and the external environment, absorbing vibratory energy and reducing the transmission of aerodynamic forces to the shoe, thereby preventing flutter-type events while maintaining the necessary clearance control.
2Object-affected harmful factors
If the shoe axial length is reduced to minimize vibratory responses, then flutter-type events are reduced, but maintaining tight clearances becomes difficult
Solution Approach 1:
The functional responsibilities are segmented between the shoe (208) and the extended housing (216). The shoe maintains the sealing clearance with the rotor, while the extended housing provides the additional axial length for structural support and damping, eliminating the need to compromise clearance control.
Solution Approach 2:
The solution moves from extending the shoe in the axial dimension to extending the housing in the radial dimension. The extended housing protrudes radially beyond the shoe's axial ends, providing the necessary structural support and damping characteristics without interfering with the axial clearance between the shoe and rotor.
3Stability of the object's composition
If additional structural support is added to reduce flutter, then damping characteristics are improved, but device complexity increases
Solution Approach 1:
The extended housing is merged with the existing seal assembly structure, integrating the damping function into the housing rather than adding a separate component. The extended housing (216) is operatively coupled to the shoe (208) and base (212), combining structural support, damping, and sealing functions into a unified assembly.
Solution Approach 2:
The extended housing serves multiple functions simultaneously: it provides additional structural support, enhances damping characteristics, maintains clearance control, and protects the shoe from aerodynamic forces. This multi-functionality reduces the need for additional specialized components, thereby limiting the increase in 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 reduces the likelihood of vibratory responses and promotes positive damping, enhancing the aero-mechanical behavior and extending the seal's life by maintaining tight clearances and controlling friction and wear.
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
the seal is susceptible to flutter-type events should the seal experience forcing that reinforces its motion at seal natural frequencies. Such events will compromise the behavior of the seal and lead to premature wear
Data Source
AI summary
A hydrostatic seal configured to be disposed between relatively rotatable components. The seal includes a base. The seal also includes a shoe operatively coupled to the base and extending axially from a forward end to an aft end to define an axial length.