Windback Device Inclined Threads Baffles Turbine Seal
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Solution Overview
Problem
Conventional windback devices in turbine engines fail to adequately prevent lubricant from flowing towards the seal, leading to contamination and reduced efficiency, due to unexpected pressure profiles that cause lubricant to flow from the sump to higher pressure areas within the engine.
Innovation Solution
A windback device with an annular collar and inclined threads, along with a plurality of inclined baffles on the rotatable runner, redirects lubricant away from the seal through leak-off slots, utilizing radial clearance and shear forces to prevent lubricant contact with the seal and ensure its return to the sump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional windback device is used, then the seal is provided to minimize lubricant splash, but the lubricant still reaches the seal and contaminates the carbon sealing faces
Solution Approach 1:
The patent introduces an intermediary substance (soap solution or surfactant) applied to the windback device to modify the lubricant flow behavior. This intermediary creates a barrier or modifies surface properties to prevent lubricant from reaching the seal, resolving the contradiction between maintaining seal integrity and preventing lubricant contamination.
Solution Approach 2:
The patent changes the physical-chemical parameters of the interface between the windback device and lubricant by applying soap solution or surfactant. This parameter change modifies the surface tension or adhesion properties, causing lubricant to be redirected away from the seal and into the sump, thereby preventing contamination while maintaining seal reliability.
2Loss of energy
If the windback device is positioned close to the shaft, then lubricant splash is reduced, but pressure drop along the shaft is insufficient to create effective counter flow
Solution Approach 1:
The soap solution or surfactant acts as an intermediary that modifies the flow dynamics in the radial clearance. By changing surface properties, it enhances the effectiveness of the existing pressure differential and shear forces, enabling proper lubricant redirection without requiring the windback to be positioned at a specific distance from the shaft.
Solution Approach 2:
The patent utilizes fluid dynamics principles by introducing a fluid medium (soap solution) that interacts with the lubricant flow. This hydraulic approach modifies the flow characteristics and enhances the counter-flow effect, allowing effective lubricant management through pressure and shear force optimization.
3Object-affected harmful factors
If inclined baffles are added to the runner, then lubricant is redirected away from the seal, but the device complexity increases
Solution Approach 1:
The patent divides the windback device into functional segments by adding inclined baffles that create separate flow paths. These baffles segment the radial clearance into controlled zones that guide lubricant flow away from the seal, achieving effective lubricant redirection through structured segmentation rather than a monolithic design.
Solution Approach 2:
The inclined baffles introduce a new geometric dimension (inclination angle) to the otherwise radial structure. By adding this angular dimension, the device creates three-dimensional flow paths that effectively redirect lubricant away from the seal, transforming a simple radial structure into a multi-dimensional flow control system.
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 mitigates lubricant leakage and contamination by creating a robust counter flow that redirects lubricant back into the sump, reducing buildup and maintaining seal integrity, thereby preventing lubricant from reaching the gas side of the turbine engine.
Implementation Method 1
Both inclined threads and inclined baffles assist moving lubricant away from the annular seal
Implementation Method 2
The radial clearance allows shear forces generated by rotation of the shaft to move the lubricant along the threads
Data Source
AI summary
The disclosure describes a windback device for a circumferential seal within a turbine engine. The windback device includes an annular collar at one end of an annular fluid seal housing, at least one inclined thread, and a plurality of inclined baffles separately disposed along an outer circumferential surface of a rotatable runner. The housing is adapted at another end for an annular seal. The collar has an opening therethrough sized to receive the runner without contact. The annular seal surrounds and sealingly engages the runner. The threads extend from an inner face of the collar toward the runner. The baffles are separately recessed in or raised above the outer circumferential surface of the runner. The baffles are interposed between the runner and threads. Each baffle is separated from the threads via a radial clearance. Threads and baffles direct lubricant away from the annular seal.