Three-Stream Gas Turbine Electric Machine for On-Shaft Power Generation
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Solution Overview
Problem
Conventional gas turbine engines face challenges in improving overall engine performance and operability, particularly in generating electrical power efficiently, as they increase in power generation and transmission capability.
Innovation Solution
A three-stream gas turbine engine architecture is introduced, featuring a primary fan, a mid-fan, and an electric machine mechanically coupled to a spool, which produces three distinct streams of propulsive thrust, optimizing tip speed ratios, radii ratios, power to voltage ratios, and power to power ratios to enhance efficiency and fuel burn benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If electric machine power generation capability is increased, then electrical power output is improved, but engine complexity increases
Solution Approach 1:
The electric machine is designed to perform multiple functions: generating electrical power during engine operation, providing torque assistance during transient conditions, and potentially serving as a starter motor. This multi-functionality allows the system to achieve high power generation capability while managing complexity by consolidating functions into a single component rather than adding separate systems.
Solution Approach 2:
The electric machine is mechanically coupled to the existing engine spool, merging the electrical power generation system with the mechanical propulsion system. This integration allows the electric machine to utilize the engine's rotational energy directly, achieving high power output without requiring a separate prime mover or complex transmission system.
2Loss of energy
If three-stream architecture is implemented, then fuel burn efficiency is improved, but device complexity increases
Solution Approach 1:
The engine airflow is divided into three distinct streams: a core stream through the turbine, a mid-fan stream, and an outer fan stream. Each stream is handled by dedicated components (core compressor, mid-fan, outer fan), allowing independent optimization of each flow path for fuel efficiency while maintaining manageable complexity through functional segmentation.
Solution Approach 2:
The three-stream architecture adds a radial dimension to the traditional axial flow engine, with fans arranged at different radii from the central axis. This dimensional expansion allows simultaneous extraction of power from multiple flow paths, improving overall efficiency by utilizing energy that would otherwise be wasted in conventional single-stream designs.
3Power
If tip speed ratios are optimized, then power generation efficiency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The design optimizes the tip speed ratio as a key operating parameter by carefully selecting the rotational speed of the electric machine relative to the blade tip speed. This parameter optimization maximizes the efficiency of energy conversion from mechanical to electrical power while the patent provides guidance ranges (0.6-1.2) that balance efficiency gains with manufacturing tolerances.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The three-stream engine design improves fuel burn efficiency and overall engine performance by optimizing thrust production and electrical power generation, offering significant advantages over conventional turbofan engines.
Implementation Method 1
A three-stream engine and methods of operating the same are provided... an electric machine mechanically coupled thereto
Implementation Method 2
The three-stream engine includes a primary fan and a mid-fan... produce three distinct streams of propulsive thrust
Implementation Method 3
a turbine section, and an exhaust section... The flow of combustion gasses through the turbine section drives the turbine section
Data Source
AI summary
A method is provided of generating electric power with an electric machine. The method includes rotating a rotor of the electric machine relative to a stator of the electric machine with a shaft of a gas turbine engine during an operating condition of the gas turbine engine, the gas turbine engine being a three-stream gas turbine engine defining an axial direction, the three-stream gas turbine engine comprising: the shaft, a primary fan operatively coupled with the shaft, a mid-fan positioned downstream of the primary fan and operatively coupled with the shaft, a low pressure turbine operatively coupled with the shaft, wherein rotating the rotor of the electric machine relative to the stator of the electric machine comprises generating an electric machine power during the operating condition and generating a low pressure turbine power during the operating condition.