Third-Stream Gas Turbine Fan Architecture for Thrust Packaging Limits
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Solution Overview
Problem
Conventional turbofan engine design faces challenges in increasing fan diameter for higher thrust while maintaining propulsive efficiency, leading to installation difficulties, weight issues, and thermal demands, without adequately addressing packaging and weight concerns.
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 generate thrust through a separate airflow path, and employing variable geometry components to optimize thrust generation across varying operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If fan diameter is increased for higher thrust, then thrust is improved, but installation difficulty and weight increase
Solution Approach 1:
The engine is divided into three separate airflow streams: a core stream through the combustor, a bypass stream around the core, and a third stream through a separate duct. This segmentation allows each stream to be optimized independently, enabling thrust enhancement without proportionally increasing overall engine size and installation complexity
Solution Approach 2:
The third stream is introduced as an additional spatial dimension for airflow, separate from the traditional two-stream bypass architecture. This allows thrust generation in an additional dimensional pathway, effectively increasing total thrust without linearly increasing fan diameter or installation footprint
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 ducts and control systems, the engine can generate additional thrust through the third stream without requiring a proportional increase in fan diameter, thereby reducing the weight penalty associated with larger fans
Solution Approach 2:
The third stream duct and associated components serve multiple functions: generating additional thrust, managing thermal loads separately from the core and bypass streams, and providing flexibility in thrust modulation. This multi-functionality reduces the need for additional dedicated components that would increase weight
3Force
If fan diameter is increased for higher thrust, then thrust is improved, but thermal management becomes more difficult
Solution Approach 1:
The thermal management system is segmented into three independent streams, allowing heat from combustion to be managed separately in the core stream while the bypass and third streams can be used for cooling or thrust generation without direct thermal exposure, simplifying overall thermal management
Solution Approach 2:
The third stream acts as an intermediary pathway that can absorb or dissipate thermal energy independently, providing an additional degree of freedom for thermal management without requiring direct intervention in the high-temperature core combustion zone
4Productivity
If three-stream design is implemented, then propulsive efficiency is enhanced, but device complexity increases
Solution Approach 1:
The engine is segmented into three functional streams with dedicated ducts and control mechanisms, allowing each stream to be optimized for specific operational requirements. This segmentation enables enhanced propulsive efficiency through independent optimization while maintaining manageable complexity through modular architecture
Solution Approach 2:
The three-stream design incorporates variable geometry components and controllable duct configurations that can dynamically adjust airflow distribution among the three streams based on operational conditions, optimizing propulsive efficiency across different flight regimes while using standardized components to control complexity
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
Maintains or enhances propulsive efficiency by balancing airflow ratios and thermal management, reducing weight and packaging constraints, and facilitating rapid design selection.
Implementation Method 1
A three-stream gas turbine engine design incorporating a primary and secondary fan, with a third stream airflow, utilizing a ducted fan to generate thrust through a separate airflow path
Implementation Method 2
employing variable geometry components to optimize thrust generation across varying operating conditions
Data Source
AI summary
A 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, a secondary fan located downstream of the primary fan within the inlet duct, and a booster located downstream of the secondary fan and comprising a booster rotor blade, an inlet guide vane, and booster cowl, the booster cowl separating an upstream portion of the fan duct into an upper fan duct having an upper fan duct inlet and a lower fan duct having a lower fan duct inlet, the upper fan duct inlet and lower fan duct inlet collectively forming the fan duct inlet, the inlet guide vane located forward of the booster rotor blade.