Three-Stream Gas Turbine Layout for High-Thrust Engine 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 thermal demands, while maintaining propulsive efficiency.
Innovation Solution
A three-stream gas turbine engine design incorporating a primary and secondary fan, with a third stream airflow, utilizing a ducted fan to manage airflow ratios and thermal management through variable geometry components, enhancing propulsive efficiency and reducing weight and packaging 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 is divided into three separate airflow streams: a core stream through the combustor, a first bypass stream, and a second bypass stream. This segmentation allows each stream to be optimized independently, enabling the fan to generate higher thrust without proportionally increasing overall engine complexity and installation difficulty.
Solution Approach 2:
The patent introduces a vertical dimension to the bypass airflow by directing a portion of the bypass stream downward through a lower bypass duct, separate from the traditional horizontal bypass path. This dimensional change allows for compact engine packaging and reduced installation space requirements while maintaining high thrust output.
2Force
If fan diameter is increased for higher thrust, then thrust is improved, but weight increases
Solution Approach 1:
By segmenting the bypass flow into two separate streams with independent ducts, the engine can achieve higher thrust through optimized airflow paths without requiring a single large, heavy fan structure. Each bypass stream can use smaller, lighter components while collectively producing the required thrust.
Solution Approach 2:
The second bypass stream is nested within the overall engine structure, with its duct positioned below the core and first bypass ducts. This nesting allows for compact arrangement of components, reducing the overall engine envelope and associated structural weight while maintaining high thrust capability.
3Force
If fan diameter is increased for higher thrust, then thrust is improved, but thermal demands increase
Solution Approach 1:
The thermal load is segmented across three independent airflow streams, allowing heat management to be optimized for each stream separately. The core stream handles combustion temperatures, while the two bypass streams provide cooler airflow paths, reducing overall thermal demands on the engine structure and enabling higher thrust without excessive heating.
Solution Approach 2:
The second bypass stream acts as a thermal intermediary, providing a cool airflow path that helps manage engine temperatures. By introducing this additional cooling airflow separate from the primary bypass stream, the engine can sustain higher thrust levels without exceeding thermal limits of critical components.
4Productivity
If three-stream design is implemented, then propulsive efficiency is improved, but device complexity increases
Solution Approach 1:
The engine is segmented into three airflow streams with dedicated ducts and exit paths. This segmentation enables each stream to be optimized for specific propulsive functions, improving overall propulsive efficiency through tailored airflow management despite the increased structural complexity of having separate ducts and control systems.
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.