Gas Turbine Vane Segmented Fillets for Combustion Vibration
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Solution Overview
Problem
Combustion vibration caused by acoustic transmission between the outlet portions of combustors in gas turbines hinders stable operation, and existing fillet designs on the first-stage stationary vane can limit the reduction of this vibration by increasing the distance between the vane and the combustors.
Innovation Solution
The first-stage stationary vane design features separated pressure-surface and suction-surface fillet portions at the leading edge, with a flat upstream-side end surface and fillet radius increasing portions, and includes cut-out portions to reduce thermal stress and metal temperature, allowing for closer proximity to the combustors and minimizing acoustic transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a fillet portion is disposed over the entire periphery of the vane portion at the boundary to the shroud wall portion, then the structural integrity and stress distribution are improved, but the distance between the vane portion and the outlet portions of the combustors increases, limiting the reduction of combustion vibration
Solution Approach 1:
The fillet portion is segmented into a pressure-surface side fillet portion and a suction-surface side fillet portion that are separated at the leading edge side of the vane portion. This segmentation allows each fillet portion to be positioned optimally without the other interfering, enabling the vane portion to be placed closer to the combustor outlet while maintaining structural integrity through localized stress distribution at the shroud wall boundary.
2Object-affected harmful factors
If the distance between the vane portion and the outlet portions of the combustors is reduced to block acoustic transmission, then combustion vibration is reduced, but the fillet portion on the leading edge side hinders this reduction
Solution Approach 1:
By segmenting the fillet portion into pressure-surface and suction-surface sides that are separated at the leading edge, the design removes the obstacle that previously prevented reducing the distance to the combustor outlet. This enables the vane portion to be positioned closer to the combustor outlet portions, effectively blocking acoustic transmission pathways and reducing combustion vibration between adjacent combustors.
3Stress or pressure
If the fillet radius is increased to reduce thermal stress, then the thermal stress and metal temperature are mitigated, but the distance between the vane and combustors increases
Solution Approach 1:
The segmented fillet configuration allows each side's fillet radius to be optimized independently for thermal stress reduction without increasing the overall leading edge profile. The pressure-surface side fillet portion and suction-surface side fillet portion can each have increased fillet radii to mitigate thermal stress and metal temperature, while the separation at the leading edge prevents these increased radii from interfering with reducing the distance to the combustor.
Data Source
AI summary
A first-stage stationary vane of a gas turbine includes: a vane portion including a pressure surface and a suction surface; a shroud wall portion which connects to an end portion of the vane portion and which forms a flow passage wall; a pressure-surface side fillet portion disposed on a corner portion formed by the pressure surface and a wall surface of the shroud wall portion; and a suction-surface side fillet portion disposed on a corner portion formed by the suction surface and the wall surface of the shroud wall portion. The pressure-surface side fillet portion and the suction-surface side fillet portion are separated at a leading-edge side of the vane portion so as not to connect to each other.