Circumferential Seal Assembly With Adjustable Pressure-Balanced Seating
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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 can result in engine issues like overheating and lubricant loss.
Innovation Solution
A circumferential seal assembly comprising a primary sealing ring, a second sealing ring, and a third sealing ring, along with an insert, which defines cavities to manage pressure forces and fluid flow, minimizing contact forces and allowing for self-adjustment to maintain effective sealing across face and radial surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional circumferential seals with coil springs and garter springs are used to maintain sealing contact, then sealing effectiveness is improved, but excessive wear and heating occur at higher shaft speeds and pressures
Solution Approach 1:
A fluid intermediary is introduced between the seal ring and sealing surfaces. The fluid pressure creates a hydrostatic film that separates the seal ring from the face sealing surface and radial sealing surface, reducing direct contact and thereby minimizing wear and heating while maintaining sealing effectiveness
Solution Approach 2:
The patent utilizes fluid pressure (hydraulic principle) to generate lifting forces on the seal ring. By controlling fluid pressure in cavities behind the seal ring, the system creates hydrostatic support that reduces contact forces between sealing surfaces, solving the contradiction between maintaining seal contact and reducing wear/heating
2Power
If higher shaft speeds and pressures are used to enhance turbine engine performance, then power output is improved, but sealing stability deteriorates leading to fluid mixing between compartments
Solution Approach 1:
The seal ring is designed with dynamic characteristics that allow it to adapt to varying operating conditions. The flexible seal ring can adjust its position and contact pressure in response to changes in shaft speed and pressure, maintaining sealing stability across a wide range of dynamic operating conditions
Solution Approach 2:
The system changes fluid pressure parameters to control seal ring position and contact forces. By adjusting fluid pressure in response to operating conditions, the seal maintains stability even as shaft speed and system pressure vary, preventing fluid mixing between compartments
3Reliability
If increased contact forces are applied to maintain sealing engagement, then sealing effectiveness is improved, but coolant requirements increase
Solution Approach 1:
The patent replaces mechanical contact-based sealing with a fluid-film-based sealing system. Instead of relying on high contact forces between solid surfaces, the system uses fluid pressure to create a separating film, thereby maintaining sealing effectiveness while dramatically reducing the need for coolant to manage frictional heating
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 on sealing surfaces, reduces coolant requirements, and ensures effective fluid separation, enhancing the reliability and efficiency of turbine engines by maintaining balanced pressure forces across varying operating conditions.
Implementation Method 1
A garter spring may be disposed within a groove about the circumference of the circumferential seal
Implementation Method 2
a coil spring disposed within a pocket at one side of the circumferential seal
Implementation Method 3
A forward pressure is communicated across the forward face via a fluid contacting the circumferential seal
Implementation Method 4
An aft pressure is communicated across an aft face via a fluid contacting the circumferential seal
Implementation Method 5
An inward pressure is communicated across an outer circumferential surface via a fluid contacting the circumferential seal
Implementation Method 6
An outward pressure is communicated across the inner circumferential surface via a fluid contacting the circumferential seal
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.