Circumferential Seal Assembly With Self-Adjusting Seating Forces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbine engines face challenges in maintaining effective sealing at higher shaft speeds and pressures, leading to excessive wear, heating, and leakage due to imbalanced seating forces across face and radial sealing surfaces, which can result in engine performance degradation and safety issues.
Innovation Solution
A circumferential seal assembly comprising a primary sealing ring, a second sealing ring, a third sealing ring, and an insert, which are strategically positioned and biased to minimize contact forces and maintain a self-adjusting force balance across the sealing surfaces, using materials like carbon and metal, and incorporating features such as seal bore dams, garter springs, and exhaust ports to manage pressure differentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional circumferential seal designs are used at higher shaft speeds and pressures, then sealing function is maintained, but excessive wear and heating occur due to imbalanced seating forces
Solution Approach 1:
The patent modifies the seating force parameters by introducing adjustable spring mechanisms (garter springs and coil springs) that can be tuned to achieve optimal force balance. The spring rates and preloads are specifically designed to maintain balanced seating forces under varying operating conditions, particularly at higher shaft speeds and pressures, thereby reducing excessive wear and heating while maintaining reliable sealing performance
2Power
If higher shaft speeds and pressures are used to enhance turbine engine performance, then power output increases, but sealing effectiveness deteriorates due to imbalanced forces
Solution Approach 1:
The patent implements dynamic force balancing through spring mechanisms that automatically adjust seating forces in response to varying operating conditions. The springs provide continuous adaptive compensation for changes in shaft speed and pressure, ensuring that sealing effectiveness is maintained across the full operating range without requiring manual intervention or fixed force settings
3Reliability
If increased seating forces are applied to prevent leakage, then sealing performance improves, but wear and heating increase excessively
Solution Approach 1:
The patent employs spring mechanisms that apply counterbalancing forces to achieve equilibrium between seating forces and opposing pressures. The garter springs and coil springs are configured to provide just sufficient seating force to maintain sealing effectiveness while counteracting excessive forces that would lead to wear and heating, creating a self-balancing system
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 effectively minimizes wear and heating along sealing surfaces, reduces coolant requirements, and maintains efficient sealing performance by self-adjusting to balance forces, thereby enhancing turbine engine reliability and safety.
Implementation Method 1
A garter spring is disposed within a groove about the circumference of the circumferential seal and urges the circumferential seal in the direction of a radial sealing surface
Implementation Method 2
A coil spring is disposed within a pocket at one side of the circumferential seal and urges the circumferential seal in the direction of a forward sealing surface
Implementation Method 3
A forward pressure is communicated across the forward face via a fluid contacting the circumferential seal. The forward pressure imparts a forward face force in the direction of the higher pressure side
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 primary sealing ring sealingly engages both a face sealing surface along a housing and a radial sealing surface along a rotatable element. The primary sealing ring, the second sealing ring, and the third sealing ring cooperate, in combination with the housing, the rotatable element, and/or the insert, both to define and to separate a first cavity at the higher pressure side and a second cavity at the lower pressure side. In some embodiments, the second sealing ring sealingly engages a face of the primary sealing ring. In other embodiments, the second sealing ring sealingly engages a circumferential surface of the primary sealing ring.