Compressor Stage Vane Baulking Tab Asymmetry
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Solution Overview
Problem
The existing compressor stage designs in gas turbine engines face challenges with back-to-front installation of static vanes, leading to increased casing radius, weight, and thermal mass, which complicates thermal response and can cause stress issues.
Innovation Solution
Incorporating a baulking tab and baulking land configuration in the static vanes and casing, where the baulking tab projects radially outward to interfere with the baulking land if the vane is installed incorrectly, preventing back-to-front installation and reducing the overall casing radius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tenons are positioned at different radii to prevent back-to-front installation, then installation direction can be controlled, but casing radius increases leading to increased weight and thermal mass
Solution Approach 1:
The patent applies asymmetry by positioning the baulking tab and baulking land at different radial locations to create a non-symmetric configuration that prevents back-to-front installation. The baulking tab on the vane and corresponding baulking land on the casing are offset radially, ensuring that only the correct installation orientation allows proper alignment and assembly.
2Reliability
If tenons are positioned at different radii to prevent back-to-front installation, then installation direction can be controlled, but thermal mass increases complicating thermal response tuning
Solution Approach 1:
The asymmetric positioning of the baulking tab and baulking land creates a configuration where the tenons can be at the same radius, avoiding the need to increase casing radius for prevention features. This maintains a more compact casing geometry with reduced thermal mass, allowing better thermal response characteristics.
3Reliability
If tenons are positioned at different radii to prevent back-to-front installation, then installation direction can be controlled, but stress and lifing issues occur for the vanes
Solution Approach 1:
The baulking tab and baulking land configuration creates an asymmetric mechanical interlock that prevents incorrect installation without requiring radial offset of tenons. This symmetric tenon positioning distributes loads more evenly across the vane-casing interface, reducing stress concentrations and improving vane lifing characteristics.
4Reliability
If baulking tab and baulking land are configured to prevent back-to-front installation, then incorrect installation is prevented, but device complexity increases
Solution Approach 1:
The prevention mechanism is segmented into distinct components: the baulking tab on the vane and the baulking land on the casing. This segmentation allows each component to be designed and manufactured independently, simplifying the overall implementation while achieving the prevention function through their coordinated interaction during assembly.
Data Source
AI summary
A compressor stage of a gas turbine engine is provided. The compressor stage has a circumferential row of static vanes and a radially outer casing. Each vane has a radially outer and forwardly projecting front tenon which on build of the compressor stage is received into a first recess of the casing. Each vane also has a radially outer and rearwardly projecting rear tenon which on build of the compressor stage is received into a second recess of the casing. Each vane further has a baulking tab adjacent one of the front and the rear tenons. The casing has a respective baulking land adjacent the recess into which the other of the front and the rear tenons is received. The baulking tab and the baulking land are configured such that if the vane is attempted to be installed in the stage back-to-front, the baulking tab interferes with the baulking land to prevent completion of the build of the compressor stage.