Variable Speed Ratio Coupling for Gas Turbine Compressor Boost Stage
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Solution Overview
Problem
The fixed speed ratio between compressor boost stages and low pressure spools in gas turbine engines limits the ability to vary the overall pressure ratio during operation, making it difficult to adapt to different operational conditions.
Innovation Solution
A system that allows for changing the speed ratio between the compressor boost stage and the power turbine by using coupling devices and auxiliary power devices to decouple and re-couple the boost stage from the power turbine, enabling the adjustment of rotational speeds relative to the power turbine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed speed ratio is used between the compressor boost stage and the low pressure spool, then the mechanical coupling is simple and reliable, but the ability to vary the overall pressure ratio during operation is limited
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a fixed speed ratio coupling to a variable speed ratio coupling mechanism. The system includes a first coupling device that can be selectively engaged or disengaged, and a second coupling device with variable speed ratio capability. This allows the boost stage to be dynamically coupled to the low pressure spool at different speed ratios depending on operational requirements, thereby improving adaptability while maintaining mechanical coupling reliability.
Solution Approach 2:
The patent applies segmentation by dividing the coupling mechanism into multiple independent coupling devices: a first coupling device for selective engagement and a second coupling device for variable speed ratio transmission. This segmentation allows each coupling device to perform specific functions independently, enabling the system to achieve both simple mechanical coupling and variable speed ratio capability through coordinated operation of the segmented components.
2Adaptability or versatility
If the boost stage is mechanically coupled to the low pressure spool at a fixed speed ratio, then the transmission is straightforward, but the system cannot adapt to different operational conditions requiring varying pressure ratios
Solution Approach 1:
The system implements dynamic adaptability through the selective engagement and disengagement of the first coupling device and the variable speed ratio capability of the second coupling device. This allows the boost stage to be coupled to the low pressure spool at different speed ratios based on operational conditions such as take-off, cruise, or landing, enabling the system to adapt to varying operational requirements while maintaining ease of operation through automated or manually controlled coupling mechanisms.
3Speed
If a variable speed ratio coupling is implemented, then the ability to adjust rotational speed is improved, but the device complexity increases
Solution Approach 1:
The patent implements variable speed ratio capability through the second coupling device, which allows the rotational speed of the boost stage to be adjusted relative to the low pressure spool. This dynamic speed adjustment is achieved through the variable speed ratio mechanism, enabling the system to optimize performance across different operating conditions while the overall complexity is managed through the modular design of the coupling system.
Solution Approach 2:
The second coupling device acts as an intermediary between the low pressure spool and the boost stage, providing variable speed ratio transmission. This intermediary mechanism allows for smooth and controlled speed adjustment, mediating the interaction between the two rotating components and enabling flexible speed control without directly exposing the complexity of the variable ratio mechanism to the rest of the system.
Data Source
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AI summary
A system for changing a speed ratio between a compressor boost stage (12) and at least one power turbine (16) of a gas turbine engine (10) comprises a coupling device (20) configured to selectively transmit energy from the at least one power turbine (16) to the boost stage (12) according to at least a first speed ratio and a second speed ratio. The system also comprises an auxiliary power device (22, 26) configured to cause a rotational speed of the boost stage (12) to change from a first speed corresponding substantially to the first speed ratio to a second speed corresponding substantially to the second speed ratio when the boost stage (12) is decoupled from the at least one power turbine (16).