Split Axial-Centrifugal Compressor Variable-Ratio Drive
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Solution Overview
Problem
Gas turbine engines with multiple compressor stages driven at a single rotational speed face efficiency limitations, while those with separate turbine units for each stage suffer from cost and complexity issues, and stability problems arise when rotational speeds are dependent on the output shaft.
Innovation Solution
Incorporating a variable-ratio unit, such as a toroidal or planetary-type ball variator, to transmit rotational power from the turbine to both axial and centrifugal compression stages, allowing them to operate at various speeds offset from the turbine speed, thereby optimizing the operation of each stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If multiple compressor stages are driven at a single rotational speed by the turbine, then the device complexity is reduced, but the operating efficiency deteriorates
Solution Approach 1:
The compressor is divided into multiple independent stages (axial compression stage and centrifugal compression stage) that can rotate at different speeds. Each stage is driven by the turbine through separate drive systems, allowing each stage to operate at its optimal rotational speed independently, thereby improving overall compressor efficiency without requiring a single complex multi-speed turbine system
Solution Approach 2:
The turbine serves multiple functions by simultaneously driving both the axial and centrifugal compression stages through a common drive system. This universal drive approach allows a single turbine to provide power to multiple compressor stages at different rotational speeds, achieving efficient compression across the entire system without requiring separate turbine units for each stage
2Productivity
If multiple turbine units are used to drive each compressor stage at different rotational speeds, then the operating efficiency is improved, but the device complexity and cost increase
Solution Approach 1:
Multiple turbine units are merged into a single common turbine that drives both the axial and centrifugal compression stages. The turbine is positioned to provide rotational power to both stages through a unified drive system, eliminating the need for separate turbine units while maintaining the ability to operate each compressor stage at its optimal speed through the variable-ratio transmission mechanism
3Device complexity
If one of the rotational speeds is dependent upon the rotational speed of the output shaft, then the device complexity is reduced, but the stability deteriorates
Solution Approach 1:
The variable-ratio transmission mechanism provides dynamic speed control for the compressor stages, allowing the rotational speeds to be independently adjusted and optimized based on operating conditions. This dynamic adjustment capability enables each compression stage to maintain stable operation at its optimal speed regardless of variations in turbine speed or output shaft rotational speed, improving overall system stability
Data Source
AI summary
A gas turbine engine including a compressor, a turbine, and a variable-ratio unit is disclosed. The turbine is coupled to the compressor to drive rotation of multiple stages of the compressor. The variable-ratio unit is configured to transmit rotational power from the turbine to at least one stage of the compressor to drive rotation of the at least one stage of the compressor.