Hydrodynamic Seal Groove Layout for High-Altitude Film Stability
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Solution Overview
Problem
Aerospace sealing systems face challenges in maintaining a hydrodynamic film across varying altitude and pressure conditions, leading to increased wear and potential damage due to reduced source pressure, as shallow grooves are insufficient at high altitudes and deep grooves cause higher liftoff speeds and increased wear during engine startup and shutdown.
Innovation Solution
Incorporating a combination of shallow and deep hydrodynamic grooves in an alternating pattern on a sealing component, allowing for hydrodynamic film generation at low rotor speeds and maintenance at very low source pressures, with groove depths tailored for specific operational conditions and a land-to-groove surface area ratio of 1:1 or less to minimize contact and enhance seal life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shallow hydrodynamic grooves are used, then liftoff speed is reduced and seal wear during normal operation is minimized, but the seal cannot maintain a hydrodynamic film at high altitudes with reduced source pressure
Solution Approach 1:
The sealing component is segmented into multiple groove zones with different depths. Shallow grooves are positioned in regions where they can generate hydrodynamic film at low speeds during normal operation, while deep grooves are positioned to provide fluid reservoir capacity when source pressure is reduced at high altitudes. This spatial segmentation allows the seal to address both contradictory requirements in different locations.
Solution Approach 2:
Different regions of the sealing component are given different groove depths tailored to local operational requirements. The varying groove depths create local variations in fluid storage and hydrodynamic generation capabilities, allowing the seal to adapt to different pressure conditions in different operational phases without compromising overall performance.
2Quantity of substance
If deep hydrodynamic grooves are used, then sufficient working fluid volume is available at reduced source pressure, but liftoff speed increases and seal wear during startup increases
Solution Approach 1:
The groove structure is segmented into shallow and deep zones, where deep grooves provide fluid reservoir capacity without dominating the entire sealing surface. This segmentation ensures that sufficient working fluid volume is available when needed (at high altitude) while limiting the overall groove volume to prevent excessive liftoff speed and startup wear.
Solution Approach 2:
The groove depth parameter is varied across different regions of the sealing component. By changing the groove depth parameter locally rather than uniformly, the design optimizes the balance between fluid storage capacity and hydrodynamic film generation speed, reducing startup wear while maintaining adequate fluid volume for high-altitude operation.
3Reliability
If deep hydrodynamic grooves are used, then hydrodynamic film is maintained at high altitude, but film is lost at higher rotor speeds during shutdown causing increased wear
Solution Approach 1:
The sealing component uses segmented groove depths to balance film maintenance and shutdown performance. Shallow grooves help maintain hydrodynamic film at higher rotor speeds during shutdown by preventing excessive fluid storage that would reduce fluid velocity, while deep grooves ensure adequate fluid supply at high altitudes. This segmentation resolves the contradiction between film maintenance and shutdown durability.
4Adaptability or versatility
If single-depth hydrodynamic grooves are used, then manufacturing is simplified, but the seal cannot optimize performance across wide operational range from sea level to high altitude
Solution Approach 1:
The groove system is segmented into multiple depth zones to provide adaptability across different operational conditions. This segmentation allows the seal to optimize performance for both sea level and high altitude operations, as well as different rotor speeds, without requiring multiple separate sealing components.
Solution Approach 2:
The multi-depth groove configuration serves multiple functions within a single sealing component: it provides hydrodynamic film generation at various speeds, maintains fluid supply at different source pressures, and adapts to different altitude conditions. This multi-functionality achieves wide operational range coverage without proportionally increasing device 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 effectively reduces seal wear and maintains a hydrodynamic film across a wide operational range, preventing sealing interface contact and extending seal life by optimizing groove depth and configuration for aerospace applications.
Implementation Method 1
The source pressure can, inter alia, aid in driving a working fluid into associated hydrodynamic grooves so that there is sufficient volume of a working fluid to create a hydrodynamic effect (e.g., a film).
Data Source
AI summary
A hydrodynamic sealing component includes a land portion and a plurality of hydrodynamic grooves. The hydrodynamic sealing component may include sets of shallow grooves and deep grooves. In embodiments, the hydrodynamic sealing component may include alternating shallow grooves and deep grooves, or alternating pairs of shallow grooves and pairs of deep grooves. In embodiments, a hydrodynamic sealing component may include at least three sets of hydrodynamic grooves, wherein each set of hydrodynamic grooves may have a different depth, which may be configured to create or maintain hydrodynamic forces over a different operational range. In embodiments, a hydrodynamic sealing component may have a surface area of lands-to-grooves is 1:1 or less. A sealing assembly, which may include a rotor with hydrodynamic grooves on a sealing surface, is also disclosed.