Gas Turbine Fan Casing Coupling Redesign
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Solution Overview
Problem
The conventional positioning of the mechanical coupling between the fan casing and the air intake section in gas turbine engines increases the size and weight of the nacelle and fan casing, and poses a risk of fan blade damage during installation and removal due to the extended length.
Innovation Solution
The mechanical coupling between the fan casing and air intake is repositioned within a specific axial range relative to the fan blade's leading edge, allowing for a shorter fan casing and reduced weight, with the flange acting as a stiffening ring to enhance rigidity and minimize clearance asymmetries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the mechanical coupling point is positioned forward of the fan blade tip (conventional arrangement), then sufficient space is provided for manipulating fan blade installation and removal, but the size and weight of the fan casing and nacelle increase
Solution Approach 1:
The patent creates an angled section in the fan casing that extends axially at an angle relative to the engine axis, utilizing three-dimensional spatial arrangement to provide manipulation space without increasing overall engine length. This dimensional approach allows sufficient clearance for blade installation tools and operations while maintaining a compact axial footprint.
Solution Approach 2:
The angled section of the fan casing is nested within the overall nacelle structure, with the straight section and angled section forming a compact integrated configuration. This nesting allows the manipulation space to be incorporated within the existing structural envelope rather than adding external extensions.
2Ease of operation
If the mechanical coupling point is positioned forward of the fan blade tip, then fan blade manipulation space is available, but the risk of fan blade catching or striking the fan casing and intake during removal increases
Solution Approach 1:
The fan casing is segmented into a straight section and a separate angled section, allowing the manipulation space to be spatially separated from the critical blade path area. This segmentation enables safe blade removal operations by providing clearance without placing structural elements in the blade extraction trajectory.
3Weight of stationary object
If the mechanical coupling point is repositioned rearward to reduce size and weight, then the risk of fan blade damage decreases, but sufficient space for blade manipulation may be compromised
Solution Approach 1:
By introducing an angled section that extends in a direction at an angle to the engine axis, the patent provides manipulation space in a radial-directional component rather than solely in the axial direction. This allows the coupling point to be repositioned rearward while still providing adequate clearance for blade installation operations through three-dimensional spatial arrangement.
Data Source
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AI summary
There is disclosed a gas turbine engine for an aircraft comprising: a propulsive fan having a plurality of fan blades; a fan casing; and an air intake; wherein the air intake is mechanically coupled to the fan casing at a point having an axial position that is within a range of axial positions from a first axial position that is rearward of the leading edge of the fan blade at its radial tip by an axial component of a blade chord length, to a second axial position that is forward of the leading edge of the fan blade tip by an axial component of the blade chord length.