Centrifugal Compressor Cover Sealing via Upstream Flange Segmentation
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Solution Overview
Problem
The existing designs for centrifugal compressor covers in turbine engines face challenges in achieving perfect sealing due to mechanical and thermal stresses, leading to pressure loss and reduced performance, especially when accessing fixing means during assembly is restricted by the cover's shape or blocked by other parts.
Innovation Solution
The proposed solution involves an upstream edge cover with pre-positioned fixing means accessible through openings, allowing for clamping and sealing without modifying the turbine engine design, using a screw and nut system with an outer flange that ensures a sealed connection upstream of the offtake openings, and a downstream flange for additional sealing and easy assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover is fixed to the casing by means of an annular flange positioned downstream on the cover, then the sealing of the recovery space downstream of the offtake openings is easily ensured, but the sealing upstream of the offtake openings cannot be ensured, leading to pressure loss and reduced performance
Solution Approach 1:
The flange is divided into two separate flanges: a first flange positioned upstream of the offtake openings and a second flange positioned downstream. This segmentation allows each flange to independently ensure sealing in its respective region, solving the problem of incomplete sealing when using a single downstream flange.
Solution Approach 2:
The first flange is pre-positioned upstream of the offtake openings before assembly, establishing the sealing structure in advance. This preliminary positioning ensures that the upstream sealing surface is ready and properly aligned before the cover is fully assembled, preventing pressure loss in the upstream region.
2Reliability
If a flange is bolted on the upstream portion of the cover to ensure sealing in this region, then perfect sealing can be achieved, but accessibility to the fixing means during assembly is blocked by the cover shape or other parts
Solution Approach 1:
The fixing means are positioned on the peripheral surface of the first flange, utilizing the radial dimension to provide access paths that are not blocked by the cover body. This dimensional arrangement allows fixing tools to reach the fastening elements from the side, overcoming the accessibility problem caused by the cover's geometry.
Solution Approach 2:
The first flange acts as an intermediary structure that provides a accessible surface for the fixing means. By positioning the fastening elements on the flange's peripheral surface rather than directly on the cover body, the flange serves as a mediator that enables tool access while maintaining the sealing function.
3Productivity
If the cover is designed with minimal clearance from rotor blades to optimize compressor efficiency, then performance is improved, but mechanical and thermal stresses cause significant deformation of the cover and rotor blades, compromising sealing
Solution Approach 1:
The sealing system is designed to accommodate dynamic deformations caused by mechanical and thermal stresses. The flexible sealing elements and the two-flange configuration allow the cover to deform within certain limits while maintaining sealing integrity, adapting to the dynamic nature of the compressor operation.
Solution Approach 2:
The sealing surfaces are designed with compensating features that anticipate and cushion against deformation. By pre-designing the sealing geometry to accommodate expected deformations, the system maintains sealing effectiveness despite the minimal clearance and resulting stress-induced shape changes.
Data Source
AI summary
A cover of a centrifugal compressor intended to be rigidly connected to a turbomachine housing, which includes a plurality of ports, is provided. The cover further includes a fastening device for fastening the cover to the housing. A portion of the fastening device is located upstream relative to the ports and can be accessed by a fastening tool through at least one of the ports of the cover. A turbomachine uses this cover to form a sealed space, in particular with a view to collecting air.