Hydrostatic Non-Contact Seal Assembly for Rotor-Stator Gaps
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Solution Overview
Problem
Rotational equipment faces inefficiencies and high manufacturing costs due to heat generation from contact seals, which can lead to internal stresses and require specialty materials, while non-contact seals are difficult to configure and may need frequent replacement upon incidental contact.
Innovation Solution
A hydrostatic non-contact seal assembly featuring an annular base, radially arranged shoes, and spring elements connecting the shoes to the base, which creates a controlled leakage and maintains clearance between rotor and stator structures using aerodynamic forces and secondary seals to prevent contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact seal with a seal element is used to seal gaps between rotors and stators, then sealing effectiveness is improved, but heat generation increases significantly reducing efficiency and subjecting components to high temperatures and internal stresses
Solution Approach 1:
The patent replaces the mechanical contact seal system with a hydrodynamic non-contact seal system. Instead of using a seal element that physically contacts the rotor, the invention uses a shoe with a bearing surface that maintains a fluid film between the rotor and stator, eliminating direct mechanical contact and the associated heat generation while maintaining sealing effectiveness
Solution Approach 2:
The patent employs hydrodynamic principles by using a fluid (liquid or gas) to create a pressurized film between the shoe bearing surface and the rotor. This fluid film serves dual purposes: it prevents direct contact between moving and stationary components (reducing heat) and maintains the seal function by preventing leakage across the gap
2Duration of action of stationary object
If specialty high temperature materials are used to accommodate high temperatures from contact seals, then component durability is improved, but manufacturing and servicing costs increase significantly as well as the mass of the rotational equipment
Solution Approach 1:
By replacing the contact seal system with a non-contact hydrodynamic seal system, the patent eliminates the source of high temperatures that would require specialty materials. This substitution allows the use of standard materials with lower manufacturing costs while maintaining or improving component durability through reduced thermal stress and wear
Solution Approach 2:
The patent extracts and removes the heat-generating contact seal element from the system. By eliminating the direct contact mechanism, the source of high temperatures is removed, making specialty high-temperature materials unnecessary and reducing manufacturing costs and equipment mass
3Temperature
If non-contact seals are used to reduce heat within rotational equipment, then heat generation is reduced, but configuration difficulty increases and components may need replacement when incidental contact occurs
Solution Approach 1:
The hydrodynamic non-contact seal is designed to be self-regulating. The shoe automatically adjusts its position relative to the rotor based on the hydrodynamic pressure generated by the fluid flow. When the gap increases, fluid pressure builds up and pushes the shoe closer to the rotor, and vice versa, maintaining optimal clearance without external control mechanisms
Solution Approach 2:
The seal system incorporates dynamic elements including the movable shoe that can adjust its position, spring elements that provide restoring force, and fluid flow that dynamically balances the forces on the shoe. This dynamic design allows the seal to adapt to varying operating conditions while maintaining the non-contact condition and reducing heat generation
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 reduces heat transfer and internal stresses, lowers manufacturing costs, and minimizes the need for replacement by maintaining a consistent seal without direct contact, enhancing the operational efficiency and reliability of rotational equipment.
Implementation Method 1
a plurality of spring elements (232). The shoes (226) may be arranged around and radially adjacent the seal land (84). Each of the spring elements (232) may be radially between and connect a respective one of the shoes (226) to the base (224)
Implementation Method 2
A hydrostatic non-contact seal (78) may be included in the seal assembly (60). The non-contact seal (78) may include an annular base (224), a plurality of shoes (226) and a plurality of spring elements (232)
Data Source
Figure 1
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AI summary
Assemblies are provided for rotational equipment. One of these assemblies includes a rotor disk structure 116, a stator structure 54 and a seal assembly 60. The rotor disk structure 116 includes a rotor disk 120 and a seal land 84 circumscribing the rotor disk 120. The stator structure 54 circumscribes the seal land 84. The seal assembly 60 is configured for sealing a gap between the stator structure 54 and the seal land 84, where the seal assembly 60 includes a noncontact seal 78. A corresponding aircraft propulsion system is also provided.