Flanged Joint Fastener Cover With Balance and Windage Shielding
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Solution Overview
Problem
Gas turbine engines experience aerodynamic drag and frictional heating due to the interaction of air flow with exposed bolts in flanged joints, leading to inefficiencies and potential damage from windage losses.
Innovation Solution
A fastener cover with annular, axially-extending walls and radial interconnections forms a cavity to shield fasteners, incorporating balancing, sealing, and damping features, including balance weight receptacles and labyrinth seals, to reduce windage and frictional contact while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If arcuate covers (windage shields) are provided over the bolts, then aerodynamic drag and frictional heating are reduced, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into a single integrated fastener cover structure. The cover simultaneously provides windage shielding, fastener retention through pockets, balance weight accommodation, and sealing capabilities, eliminating the need for separate components for each function and thereby reducing overall device complexity while maintaining energy efficiency benefits
Solution Approach 2:
The fastener cover is designed as a multi-functional component that performs windage shielding, fastener support, balance weight accommodation, and sealing operations. This universal design allows a single component to address multiple previously separate requirements, reducing the number of parts needed and simplifying the overall assembly
2Ease of operation
If balance weights are integrated into the fastener cover, then balance adjustments can be made without disassembly, but the manufacturing precision requirements increase
Solution Approach 1:
The fastener cover is divided into functional segments including dedicated balance weight receptacles that are separately manufacturable. These receptacles can be precision-crafted as discrete elements and then integrated into the overall cover structure, allowing for high precision in critical balancing areas without requiring the entire component to be manufactured with uniform high precision
Solution Approach 2:
Balance weight receptacles are pre-formed within the fastener cover structure during manufacturing. This preliminary creation of receptacles allows for precise positioning and dimensional control of balance weight locations, ensuring accurate balancing capability while simplifying the overall manufacturing process through staged production
3Reliability
If the fastener cover includes sealing features, then leakage is prevented, but the device complexity increases
Solution Approach 1:
Sealing features are integrated directly into the fastener cover structure rather than being separate components. The cover incorporates sealing surfaces and labyrinth seal structures as built-in features, combining the sealing function with the primary fastener protection function, thereby preventing leakage without adding separate sealing systems that would increase complexity
Solution Approach 2:
The fastener cover utilizes thin film or shell-like sealing structures including labyrinth seal configurations. These thin-film sealing features provide effective leakage prevention through geometric design rather than thick rigid barriers, maintaining component simplicity while achieving reliable sealing performance
Data Source
AI summary
A fastener cover for a flanged joint including first and second annular flanges extending about an axis, comprising: an annular, axially-extending, inboard wall; an annular, axially-extending outboard wall positioned radially outboard of the inboard wall; and a first radial wall interconnecting the inboard and outboard walls, wherein, collectively, the inboard and outboard walls and the first radial wall define a cavity for receiving a portion of a fastener; at least one fastener pocket including sidewalls extending axially away from the first radial wall and defining a tubular shape, which is closed off opposite the first radial wall by a floor plate having a clearance hole passing therethrough for accepting a shank of the fastener; and wherein the cover includes a balance weight receptacle for accepting at least one balance weight.