Gas Turbine Vane Segment Ribs for Stiffness
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Solution Overview
Problem
Segmented vane designs in gas turbine engines face high vibratory stress due to high temperatures, leading to fatigue and crack formation, necessitating an increase in stiffness while minimizing weight to avoid resonance frequency excitation.
Innovation Solution
The design incorporates a platform with ribs and stiffeners around the central axis of the gas turbine engine, where the ribs intersect chord projections of the vanes, enhancing both axial and tangential stiffness without significantly increasing weight, thereby shifting natural vibration frequencies above forcing frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If segmented vane designs are used in high-temperature turbine sections, then the ability to withstand high temperatures is improved, but the structure becomes more susceptible to fatigue stress and crack formation
Solution Approach 1:
The vane structure is divided into multiple segments that are circumferentially distributed around the central axis, allowing each segment to be independently supported by the platform, thereby reducing stress concentration and improving fatigue resistance while maintaining temperature capability
Solution Approach 2:
Ribs are added protruding from the platform in a direction perpendicular to the vanes, creating a three-dimensional support structure that intersects with vane chord projections, thereby enhancing stiffness in multiple directions without significantly increasing weight
2Reliability
If the stiffness of vane segments is increased to reduce dynamic stress, then fatigue resistance is improved, but the weight of the structure increases
Solution Approach 1:
Ribs protrude from the platform in a direction perpendicular to the plane of the vanes, creating a three-dimensional stiffening structure that effectively increases axial and tangential stiffness without requiring substantial additional material, thereby minimizing weight increase
Solution Approach 2:
The ribs are strategically positioned to intersect with the projections of the vanes' chords, providing localized stiffening precisely where the dynamic stress and vibratory loads are most significant, rather than uniformly increasing the entire structure's weight
Data Source
AI summary
There is disclosed a vane segment for a gas turbine engine. The vane segment includes vanes extending radially from inner ends to outer ends. The vanes have leading edges, trailing edges, and chords extending from the leading edges to the trailing edges. A platform circumferentially extends around the central axis. The platform has an inner face facing the central axis and an opposed outer face. The inner face of the platform is connected to the outer ends of the vanes. Ribs protrude away from the outer face and have lengths extending along the outer face.