Three-Stream Gas Turbine Fan Layout for Thrust and Packaging
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Solution Overview
Problem
Conventional turbofan engine design faces challenges in increasing fan diameter for higher thrust, leading to installation difficulties, weight issues, and increased thermal demands, while maintaining propulsive efficiency.
Innovation Solution
A gas turbine engine with a primary and secondary fan configuration, incorporating a third stream with adjustable geometry and thermal management features, optimizing thrust to power airflow and core bypass ratios to enhance propulsive efficiency and address packaging and weight concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If fan diameter is increased for higher thrust, then thrust is improved, but installation difficulty increases, weight increases, and thermal demands increase
Solution Approach 1:
The engine airflow is divided into three separate streams: a first stream through the core, a second stream through the bypass passage, and a third stream through the fan duct. This segmentation allows independent optimization of each stream's characteristics, enabling thrust enhancement without proportionally increasing overall engine complexity and installation difficulty
Solution Approach 2:
The patent introduces a third stream as an additional dimension of airflow path, moving beyond the conventional two-stream architecture. This dimensional expansion allows for optimized propulsive efficiency and thrust generation without requiring excessive increases in fan diameter, thereby mitigating installation and weight issues
2Force
If fan diameter is increased for higher thrust, then thrust is improved, but weight increases
Solution Approach 1:
By segmenting the airflow into three independent streams with separate control mechanisms, the patent enables optimized mass flow distribution that generates higher thrust without requiring a proportionally larger fan structure, thereby controlling weight increase
Solution Approach 2:
The patent optimizes multiple parameters including the ratio of third stream mass flow to core stream mass flow (0.2 to 2.0), thrust to power airflow ratio (3.5 to 100), and core bypass ratio (0.1 to 5). These parameter optimizations enable enhanced thrust generation through efficient airflow management rather than simply increasing component sizes, thus controlling weight
3Force
If fan diameter is increased for higher thrust, then thrust is improved, but thermal demands increase
Solution Approach 1:
The three-stream architecture segments thermal management into independent zones: the core stream handles high-temperature combustion gases, while the bypass and fan duct streams handle cooler airflow. This segmentation allows optimized thermal treatment for each stream, reducing overall thermal demands without sacrificing thrust
Solution Approach 2:
The third stream acts as an intermediary pathway that can be optimized for specific thermal characteristics. By introducing this intermediate stream between the core and bypass streams, the patent enables graduated thermal management, where each stream can be independently cooled or heated as needed, reducing peak thermal demands on the system
4Loss of energy
If third stream mass flow ratio is optimized, then propulsive efficiency is improved, but device complexity increases
Solution Approach 1:
The third stream is designed with multi-functionality, serving both propulsive purposes and thermal management functions. This universal design allows the additional stream to contribute to propulsive efficiency while its geometry and flow characteristics can be optimized to simultaneously address thermal demands, thereby limiting the increase in overall device complexity
Data Source
AI summary
A gas turbine engine is provided. The gas turbine engine includes a turbomachine defining an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct; a primary fan driven by the turbomachine; and a secondary fan located downstream of the primary fan within the inlet duct. The gas turbine engine defines a thrust to power airflow ratio between 3.5 and 100 and a core bypass ratio between 0.1 and 10, wherein the thrust to power airflow ratio is a ratio of an airflow through a bypass passage over the turbomachine plus an airflow through the fan duct to an airflow through the core duct, and wherein the core bypass ratio is a ratio of the airflow through the fan duct to the airflow through the core duct.