Eccentric Brush Seal Assembly for Uniform Circumferential Clearance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Brush seals in gas turbine engines often experience radial offset due to manufacturing and assembly tolerances, leading to non-uniform circumferential clearance, increased fluid leakage, heat generation, and potential instability or failure of rotating components.
Innovation Solution
A brush seal design with an annular plate assembly featuring a bristle pack where the bristle bore central axis is aligned with the inner central axis and offset from the outer central axis, ensuring concentricity with the rotating component's outer diameter, thereby eliminating radial offset and achieving uniform clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the brush seal is designed to operate with radial offset due to manufacturing and assembly tolerances, then the brush seal can be installed with standard tolerances, but non-uniform circumferential clearance is present leading to increased fluid leakage
Solution Approach 1:
The brush seal design introduces asymmetry by offsetting the bristle pack center from the outer diameter center by a specific distance (e.g., 0.5mm). This asymmetric configuration compensates for the radial offset between the seal housing bore and rotating component, ensuring that the bristles maintain uniform clearance with the rotating component outer diameter despite the overall eccentric assembly. The asymmetric design transforms the manufacturing tolerance issue into a controlled geometric feature that achieves both ease of manufacture and reduced fluid leakage.
2Ease of manufacture
If the brush seal is designed to operate with radial offset, then standard manufacturing tolerances can be used, but increased interference between bristles and rotating component leads to increased heat generation
Solution Approach 1:
The asymmetric offset of the bristle pack center relative to the outer diameter center creates a geometric compensation mechanism. This asymmetry ensures that the bristles engage the rotating component with uniform pressure distribution, avoiding localized high-contact-pressure regions that would generate excessive heat. The offset distance is specifically designed to match the expected radial offset in the assembly, thereby eliminating interference and heat generation issues while maintaining standard manufacturing tolerances.
3Ease of operation
If the brush seal operates with non-uniform circumferential clearance, then assembly is simplified, but uniform clearance is required to eliminate regions of increased interference and prevent instability
Solution Approach 1:
The asymmetric design of the brush seal, with the bristle pack center offset from the outer diameter center, provides a built-in compensation mechanism for assembly misalignment. This asymmetric geometry ensures that regardless of small variations in assembly position, the bristles maintain uniform clearance with the rotating component, preventing localized interference regions. The design thus achieves both assembly simplicity and rotating component stability by transforming potential alignment errors into a controlled asymmetric configuration.
Data Source
AI summary
A brush seal includes an annular plate assembly defining a radially inner diameter having an inner central axis and a radially outer diameter having an outer central axis. The inner central axis and the outer central axis are spaced apart from each other by an offset, such that the radially inner diameter and the radially outer diameter are eccentric with respect to each other. The brush seal further includes a bristle pack. The bristle pack includes a plurality of bristles defining a bristle bore having a bristle bore central axis. The bristle bore central axis is aligned with the inner central axis and the bristle bore central axis is offset from the outer central axis. Moreover, the brush seal is disposed around a rotating component. The bristle bore central axis is aligned with a component axis of the rotating component and the bristle pack engages with the rotating component.