Differential Drive for Gas Turbine Compressor Speed Optimization
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Solution Overview
Problem
Gas turbine engines face challenges in maximizing the competing efficiencies and design speeds of high pressure compressors and turbines due to rotational speed limitations, particularly in high pressure turbine stages, which affect overall engine performance.
Innovation Solution
A differential system is introduced that connects the first and second stages of the high pressure turbine spools via bevel gear connections, allowing the high pressure compressor spool to rotate at a speed between the two, thereby optimizing rotational speeds and enhancing efficiency by averaging the input rotational speeds of the turbine stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common high speed spool connects the high pressure compressor and high pressure turbine, then the structure is simple, but the compressor cannot operate at optimal speed due to turbine rotational speed limits
Solution Approach 1:
The patent divides the single common spool into separate spools for the first and second stages of the high pressure turbine. Each turbine stage rotates on its own spool, allowing independent speed optimization. The high pressure compressor is connected to both spools through a differential mechanism, enabling it to operate at an averaged speed that exceeds what a single turbine stage could provide.
Solution Approach 2:
The patent introduces a differential mechanism that dynamically combines the rotational speeds of two turbine spools. This allows the compressor speed to be dynamically adjusted as an average of the two turbine stage speeds, providing flexibility to optimize both turbine efficiencies and compressor performance simultaneously.
2Strength
If the second stage turbine rotational speed is limited by blade stress limits, then blade integrity is maintained, but the compressor design speed cannot be achieved
Solution Approach 1:
The patent merges the power output of two turbine stages through a differential mechanism. By combining the rotational energy from both turbine spools, the system achieves a higher effective compressor drive speed than either turbine stage could provide alone, while each turbine stage remains within its safe operational speed limits.
Solution Approach 2:
The differential mechanism acts as an intermediary that converts the rotational motion of two turbine spools into a single rotational output for the compressor. This mediator allows the compressor to receive combined power from both turbine stages without requiring either turbine to exceed its speed limits.
3Loss of energy
If the first stage turbine efficiency is lower than the second stage, then the overall turbine performance is reduced, but increasing first stage speed is limited by the common spool connection
Solution Approach 1:
By segmenting the turbine into independent spools for each stage, the first stage can rotate at a higher speed optimized for its efficiency without being constrained by the speed requirements of the second stage or the compressor. This segmentation allows each turbine stage to operate at its optimal speed point.
Solution Approach 2:
The differential mechanism allows the first stage spool to rotate dynamically at a speed optimized for maximum efficiency, independent of the second stage speed. The differential combines these speeds to provide appropriate compressor drive, enabling the first stage to operate more efficiently than in a fixed common spool configuration.
Data Source
AI summary
A gas turbine engine is disclosed. In various embodiments, the gas turbine engine includes a high pressure turbine having a first stage and a second stage, the first stage connected to a high pressure turbine first stage spool and the second stage connected to a high pressure turbine second stage spool; a high pressure compressor connected to a high pressure compressor spool; and a differential system having a first stage input gear connected to the high pressure turbine first stage spool, a second stage input gear connected to the high pressure turbine second stage spool and an output gear connected to the high pressure compressor spool.