Gas Turbine Guide Vane Seals Eliminating Saw-Tooth Leakage
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Solution Overview
Problem
Conventional gas turbine engine nozzle guide vane formations experience significant 'saw-tooth' leakage gaps due to axial offset between inner and outer chordal seals, leading to inefficiencies in fluid flow and reduced turbine performance.
Innovation Solution
Designing guide vane formations where inner and outer chordal seals are mutually parallel and offset along the engine's centerline, with each seal extending in a straight line intersecting planes that are inclined at 360°/n and tangent to a conical surface, ensuring equidistant points from the centerline, allowing for polygonal linkage without 'saw-tooth' gaps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inner and outer chordal seals are positioned at the same axial location, then sealing contact is maintained, but circumferential misalignment and saw-tooth leakage gaps occur due to platform wedge angles
Solution Approach 1:
The patent transitions from a single-plane seal arrangement to a two-plane offset arrangement. Inner and outer chordal seals are positioned at different axial locations (offset by distance e), allowing each seal to contact its respective support ring at optimized positions that eliminate circumferential misalignment while maintaining sealing effectiveness.
2Object-generated harmful factors
If chordal seals are offset axially to eliminate misalignment, then leakage gaps are reduced, but seal complexity and manufacturing difficulty increase
Solution Approach 1:
The patent employs asymmetric positioning of inner and outer chordal seals relative to the platforms. The seals are offset axially by distance e and positioned at different axial locations, creating an asymmetric seal arrangement that eliminates the symmetric circumferential misalignment problem while maintaining functional effectiveness.
3Strength
If platform wedge angles are increased to prevent aerofoil overhang, then structural integrity is improved, but circumferential misalignment between seals increases
Solution Approach 1:
By moving to a two-plane offset seal arrangement, the patent decouples the relationship between platform wedge angles and seal alignment. The axial offset e allows the seals to compensate for the circumferential misalignment caused by wedge angles, enabling the use of larger wedge angles for structural integrity without compromising seal alignment.
Data Source
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AI summary
A computer-based method of designing a guide vane formation is provided. The vane formation is for use in a gas turbine engine which has a cascade of circumferentially arranged identical guide vane formations. The vane formation has radially inner and radially outer chordal seals. The method allows the elimination of "saw-tooth" leakage gaps between inner chordal seals of neighbouring vane formations and between outer chordal seals of neighbouring vane formations even when the inner and outer chordal seals are axially offset from each other.