Circumferential Seal Assembly With Adjustable Pressure Forces
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Solution Overview
Problem
Turbine engines face challenges in maintaining effective sealing at higher shaft speeds and pressures, leading to excessive wear, heating, and potential fluid mixing between compartments, which compromises performance and safety.
Innovation Solution
A circumferential seal assembly comprising a primary sealing ring, a second sealing ring, and a third sealing ring, along with an insert, that defines separate cavities to manage pressure forces and minimize leakage across face and radial sealing surfaces, utilizing features like vertical feed grooves, vent channels, and hydrodynamic grooves to redirect fluid flow and adjust pressure forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional circumferential seals are used in turbine engines operating at higher shaft speeds and pressures, then sealing function is maintained, but excessive wear and heating occur leading to reduced reliability
Solution Approach 1:
The seal assembly is divided into multiple sealing rings (primary, second, third sealing rings) with distinct functions. The primary sealing ring handles the main sealing function, while the second and third sealing rings manage pressure forces and fluid redirection, distributing the mechanical stress and reducing wear on any single component
Solution Approach 2:
The insert acts as an intermediary element between the housing and the sealing rings. It provides a stable mounting surface and helps manage pressure forces, reducing the direct mechanical stress and heating on the primary sealing ring while maintaining effective sealing
2Power
If higher shaft speeds and pressures are used to enhance turbine engine performance, then power output increases, but fluid mixing between compartments occurs compromising safety
Solution Approach 1:
The patent utilizes fluid pressure dynamics by creating cavities that redirect fluid flow. The vent channels and hydrodynamic grooves use pressure differentials to redirect fluid away from sealing surfaces, maintaining fluid isolation integrity even at higher operating pressures and speeds
Solution Approach 2:
The patent introduces vertical feed grooves and vent channels that create three-dimensional fluid management pathways. This multi-dimensional approach to fluid redirection prevents fluid mixing between compartments by providing alternative flow paths that bypass potential leakage points
3Reliability
If multiple sealing rings and cavities are added to manage pressure forces, then sealing efficiency improves, but device complexity increases
Solution Approach 1:
Each component in the seal assembly serves multiple functions. For example, the primary sealing ring both seals the interface and manages fluid flow through its grooves. The insert both provides structural support and creates cavities for pressure management. This multi-functionality reduces the need for additional separate components, balancing improved sealing efficiency with controlled 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 solution minimizes wear and heating, reduces contact forces, and prevents fluid mixing, thereby enhancing the sealing efficiency and reliability of turbine engines operating under extreme conditions.
Implementation Method 1
The garter spring 2 urges the circumferential seal 1 in the direction of a radial sealing surface 19
Implementation Method 2
The coil spring 8 urges the circumferential seal 1 in the direction of a forward sealing surface 11
Implementation Method 3
The forward pressure 7 imparts a forward face force FF in the direction of the higher pressure side 21
Implementation Method 4
The aft pressure 10 imparts an aft face force FA in the direction of the lower pressure side 22
Implementation Method 5
The inward pressure 14 imparts an inward radial force F1 in the direction of the radial sealing surface 19
Implementation Method 6
The outward pressure 18 imparts an outward radial force FO in the direction away from the radial sealing surface 19
Data Source
AI summary
A circumferential seal assembly for use between a higher pressure side and a lower pressure side is presented. The seal assembly includes a primary sealing ring, a second sealing ring, a third sealing ring, and an insert. The segmented primary sealing ring sealingly engages both a face sealing surface along a housing and a radial sealing surface along a rotatable element. The insert is disposed within and directly contacts the housing. The second sealing ring is adjacent to the primary sealing ring and sealingly engages both the primary sealing ring and the insert. The segmented third sealing ring contacts and sealingly engages the primary sealing ring opposite the housing. The insert, the second sealing ring, and the third sealing ring cooperate to form a first cavity adjacent to the second sealing ring and the third sealing ring. The primary sealing ring, the second sealing ring, the insert, and the housing cooperate to form a second cavity adjacent to the primary sealing ring. The insert and the second sealing ring separate the first cavity from the second cavity.