Circumferential Seal Assembly with Hydrostatic Seating Force Balance
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Solution Overview
Problem
Conventional circumferential seals in turbine engines experience excessive wear and heating due to imbalanced seating forces at higher shaft speeds and pressures, leading to leakage and potential mixing of fluids, which can cause engine failures.
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 minimizes seating forces and balances forces hydrostatically or hydrodynamically to maintain effective sealing at radial and face surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional circumferential seals 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 applies hydrostatic and hydrodynamic principles by introducing fluid pressure fields between the seal rings and sealing surfaces. The fluid pressure balances the seating forces on the seal rings, reducing excessive contact forces and resulting wear and heating while maintaining effective sealing at high shaft speeds and pressures
Solution Approach 2:
The patent changes the physical state and distribution of fluid pressure parameters within the seal assembly. By controlling fluid pressure distribution and introducing pressure-balancing channels, the seating forces on seal rings are dynamically adjusted to match operating conditions, preventing excessive wear and heating while maintaining sealing reliability
2Reliability
If seating forces are increased to maintain sealing at high pressures, then sealing effectiveness is improved, but wear and heating increase
Solution Approach 1:
The patent uses hydrostatic pressure fields to balance seating forces on seal rings. Fluid pressure is introduced through channels and passages to create a pressure distribution that maintains sealing effectiveness at high pressures while preventing excessive contact forces that cause wear and heating
Solution Approach 2:
The patent applies counterbalancing forces through fluid pressure to offset excessive seating forces on the seal rings. The hydrostatic pressure field creates opposing forces that balance the contact forces between seal rings and sealing surfaces, reducing wear and heating while maintaining sealing effectiveness
3Temperature
If coolant is increased to reduce heating from excessive wear, then temperature is controlled, but the root cause of imbalanced seating forces remains unresolved
Solution Approach 1:
The patent uses the same fluid system for dual purposes: sealing/force balancing and cooling. The fluid pressure fields that balance seating forces also provide cooling by reducing excessive wear, thereby controlling temperature while minimizing additional coolant requirements and system 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 assembly reduces wear and heating by minimizing contact forces, requiring less coolant and maintaining effective sealing, even at high pressures and speeds, thereby preventing fluid mixing and potential engine failures.
Implementation Method 1
balances forces hydrostatically or hydrodynamically to maintain effective sealing
Implementation Method 2
balances forces hydrostatically or hydrodynamically to maintain effective sealing
Data Source
Figure 1
Figure 2
Figure 3a~3b
AI summary
A circumferential seal assembly (30) for use between a higher pressure side (36) and a lower pressure side (37) is presented. The seal assembly (30) includes a primary sealing ring (31), a second sealing ring (32), a third sealing ring (33), and an insert (34). The primary sealing ring (30) sealingly engages both a face sealing surface (46) along a housing (35) and a radial sealing surface (45) along a rotatable element (52). The primary sealing ring (31), the second sealing ring (32), and the third sealing ring (33) cooperate, in combination with the housing (34), the rotatable element (52), and/or the insert (32), both to define and to separate a first cavity (53) at the higher pressure side (36) and a second cavity (54) at the lower pressure side (37). In some embodiments, the second sealing ring (32) sealingly engages a face (106) of the primary sealing ring (31). In other embodiments, the second sealing ring (32) sealingly engages a circumferential surface of the primary sealing ring (31).