Inclined Compressor Stages for Compact High-Bypass Gas Turbine Cores
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Solution Overview
Problem
Achieving high bypass ratios in gas turbine engines is limited by the constraints on shaft dimensions, particularly due to increased fan size, which affects the pressure mode operation and dynamics margin of the compressor stages.
Innovation Solution
Inclining at least one of the compressor stages, such as the first compressor stage, and using a blisk with an inclined web and offset bore to reduce the L/D ratio of the spool, thereby improving dynamics margin while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the fan size diameter is increased to achieve higher bypass ratio, then the bypass ratio is improved, but the shaft dimensions become constrained and the dynamics margin of compressor stages deteriorates
Solution Approach 1:
The patent applies dimensionality change by inclining the compressor stages relative to the shaft axis, transitioning from a traditional axial arrangement to an inclined geometry. This angular dimension change allows the compressor stages to be positioned more compactly along the shaft, reducing the L/D ratio and improving dynamics margin while maintaining the high bypass ratio configuration.
Solution Approach 2:
The patent changes the geometric parameter of compressor stage inclination angle, deviating from the conventional axial alignment. By optimizing the inclination angle, the design achieves a reduced L/D ratio that improves dynamics margin and allows for larger fan diameters necessary for high bypass ratio operation.
2Length of moving object
If the number of compressor stages is reduced to shorten shaft length, then the L/D ratio is improved, but the compressor efficiency deteriorates
Solution Approach 1:
Instead of reducing the number of stages, the patent repositions the existing stages in an inclined arrangement, utilizing the angular dimension to compact the shaft length while preserving all necessary compressor stages for efficient operation.
Solution Approach 2:
The patent introduces asymmetry in the compressor stage arrangement by inclining them at specific angles relative to the shaft axis, creating an optimized geometric configuration that reduces L/D ratio while maintaining the required number of stages for efficient compression.
3Reliability
If the L/D ratio of the spool is reduced through inclined compressor stages, then the dynamics margin is improved, but the device complexity increases
Solution Approach 1:
The patent merges the inclination feature directly into the blisk structure, integrating the inclined compressor stages with the disk and blade assembly. This consolidation reduces the need for separate mounting components and simplifies the overall manufacturing process despite the complex geometry.
Solution Approach 2:
The blisk structure serves multiple functions: it provides the disk structure, the blade attachments, and the inclined geometry for compact arrangement. This multi-functionality reduces the number of separate components needed, offsetting the complexity introduced by the inclined stage arrangement.
Data Source
AI summary
Structures for achieving high bypass ratio in gas turbine engines are described. A gas turbine engine includes a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section includes a first booster, a second booster, and a blisk including an inclined web and offset bore. An angle of inclination relative to a vertical plane is between 5° and 55°. The vertical plane is perpendicular to an axial direction that is parallel to a longitudinal centerline defined by the gas turbine engine. The turbine section includes a first turbine and a second turbine.