Hydraulic Seal Oil Retention via Segmented Weir Design
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Solution Overview
Problem
Existing hydraulic seal arrangements face issues where the seal collapses under gravity at engine shutdown, leading to oil loss and potential leakage upon restart, and balancing weir size to retain oil at shutdown increases heat transfer during operation.
Innovation Solution
The hydraulic seal arrangement incorporates a hydraulic trap with pockets and strategically positioned weirs to retain oil during shutdown and prevent leakage, ensuring an immediate effective seal upon engine restart without excessive immersion during normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the weir diameter is made smaller to retain more oil at shutdown, then the seal can be remade more quickly upon restart, but the web becomes more deeply immersed in oil during normal running, which increases heat transfer to the oil
Solution Approach 1:
The weir is divided into two distinct segments: a first weir positioned at a first radius that remains submerged during operation, and a second weir positioned at a second radius that extends further radially inward to retain oil at shutdown. This segmentation allows each weir to perform its specific function without interfering with the other, resolving the contradiction between oil retention and heat transfer.
Solution Approach 2:
Different portions of the seal arrangement have different functions: the first weir area is optimized for heat transfer during operation by maintaining web immersion, while the second weir area is optimized for oil retention at shutdown by extending radially inward. This local differentiation of quality and function allows the system to achieve both objectives simultaneously.
2Reliability
If the web is deeply immersed in oil during normal running to ensure seal formation, then the seal is effective, but excessive heat is transferred to the oil
Solution Approach 1:
The weir structure is segmented into two radial positions, allowing the first weir to maintain adequate web immersion for seal effectiveness while the second weir provides oil retention capability without requiring excessive immersion depth during operation.
Solution Approach 2:
The relative immersion depth of the web changes dynamically between operation and shutdown states due to the dual-weir configuration. During operation, the first weir maintains sufficient immersion for sealing while the second weir remains higher. At shutdown, centrifugal forces subside and the second weir retains oil to remade the seal quickly.
3Loss of substance
If the weir extends further radially inward to retain more oil, then oil loss at shutdown is reduced, but the device complexity increases
Solution Approach 1:
The weir is segmented into two distinct radial levels, creating a stepped configuration that provides oil retention capability without requiring a completely new structural design. This segmentation achieves the oil loss reduction goal while maintaining relative structural simplicity.
Solution Approach 2:
The dual-weir structure serves multiple functions: the first weir provides heat transfer and seal formation during operation, while the second weir provides oil retention at shutdown. This multi-functionality reduces the need for separate systems, thereby limiting the increase in 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
This design effectively retains sufficient oil to re-establish a hydraulic seal quickly at startup while minimizing heat transfer during operation by utilizing a hydraulic trap with pockets and optimized weir placement.
Implementation Method 1
the centrifugal effects arising out of the rotation of the shafts 12, 14
Implementation Method 2
creating an optimum siphon-type hydraulic seal as shown
Data Source
AI summary
A hydraulic seal arrangement for a rotating machine, particularly a gas turbine engine, comprises a hydraulic seal and a hydraulic trap. When the machine is shut down, oil is retained in the hydraulic trap. When the machine is restarted, the oil from the hydraulic trap is available to re-make the hydraulic seal, thereby reducing or avoiding the leakage that typically occurs in such seal arrangements until the flow of oil through the seal arrangement is re-established.