Variable Vane Assembly Radial Leakage Reduction
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Solution Overview
Problem
Conventional gas turbine engines with variable stator vanes face challenges in reducing radial gas leakage through platform gaps, which affects efficiency and performance.
Innovation Solution
A vane assembly design where a variable vane airfoil spans the gap between adjacent platforms, obstructing radial gas leakage, and incorporates a hollow shaft with a tapered spline and bearing system for cooling and torque transmission, allowing for adjustable positioning without inducing bending moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional variable stator vanes are used with spindles extending through engine casing holes, then the vane assembly structure is established, but radial gas leakage through platform gaps increases
Solution Approach 1:
The vane airfoil is divided into multiple segments (first vane segment, second vane segment, third vane segment) that can be assembled together. This segmentation allows the vanes to block radial gas leakage paths between platform holes while maintaining structural integrity and enabling modular assembly, thus reducing gas leakage without significantly increasing overall device complexity
Solution Approach 2:
The spindle is positioned within a bearing assembly that is nested within the engine casing structure. The bearing assembly includes a bearing housing that receives the spindle, and the entire assembly is integrated into the engine casing with minimal additional external components. This nesting approach reduces gas leakage paths while avoiding significant increases in device complexity
2Adaptability or versatility
If variable vanes are made adjustable for different operating conditions, then adaptability improves, but device complexity increases
Solution Approach 1:
The spindle serves multiple functions: it acts as a rotational axis for the variable vane, provides a mounting structure for the bearing assembly, and enables angular adjustment of the vane airfoil. This multi-functionality allows the vane assembly to be adjustable for different operating conditions while minimizing the number of separate components and reducing overall device complexity
Solution Approach 2:
The variable vane airfoil is designed to be rotatable about the spindle axis, allowing dynamic adjustment of the vane angle according to operating conditions. The bearing assembly enables smooth rotation while maintaining precise angular positioning, providing adaptability without requiring complex actuation mechanisms
3Temperature
If cooling air is provided through the hollow shaft, then cooling efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The hollow shaft is divided into multiple cooling air passages (first cooling air passage, second cooling air passage) that are formed within the shaft structure. These passages receive and distribute cooling air to different regions of the variable vane, improving cooling efficiency. The segmentation of cooling passages allows for relatively simple manufacturing compared to forming complex internal cooling channels in a solid shaft
4Loss of energy
If the vane airfoil spans the gap between adjacent platforms, then gas leakage is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The vane airfoil is segmented into multiple sections that can be assembled together to span the gap between adjacent platforms. This segmentation allows for easier manufacturing of each individual segment with less stringent precision requirements, while the assembled configuration effectively blocks radial gas leakage paths that would be difficult to prevent with a single monolithic vane
Solution Approach 2:
The spindle and bearing assembly serve as intermediary structures that provide precise positioning and alignment for the segmented vane airfoil. These intermediaries enable the vanes to be accurately positioned to span gaps between platforms without requiring extremely high manufacturing precision in the vane segments themselves
Data Source
Figure 1~2
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AI summary
Gas turbine engines and related systems involving variable vanes are provided. In this regard, a representative vane assembly (110) for a gas turbine engine includes: a first inner diameter platform (122,132); a first outer diameter platform (124,134) spaced from the first inner diameter platform (122,132); and a variable vane airfoil (136) rotatably attached to and extending between the first inner diameter platform (122,132) and the first outer diameter platform (124,134) such that at least a portion of the vane airfoil (136) extends beyond a periphery of at least one of the first inner diameter platform (122,132) and the first outer diameter platform (124,134).