Three-Stream Gas Turbine Layout for Fan Diameter Constraints
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Solution Overview
Problem
Conventional gas turbine engine designs face challenges in increasing fan diameter to enhance propulsive efficiency while managing weight, thermal demands, and packaging constraints, leading to potential decreases in overall efficiency and installation difficulties.
Innovation Solution
A three-stream gas turbine engine design incorporating a primary and secondary fan, with a third stream airflow, utilizes variable geometry components and heat exchangers to optimize airflow ratios and thermal management, maintaining or improving propulsive efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fan diameter is increased to enhance propulsive efficiency, then propulsive efficiency is improved, but weight increases and packaging becomes more difficult
Solution Approach 1:
The engine airflow is segmented into three separate streams: a core stream through the combustor, a first bypass stream around the core, and a second bypass stream (third stream) further outward. This segmentation allows each stream to be optimized independently, enabling the outer bypass stream to contribute to propulsive efficiency without requiring a single oversized fan, thus managing weight and packaging constraints.
Solution Approach 2:
The patent introduces a radial dimension to the bypass flow by creating an outer bypass stream that flows through an annular passage between the first bypass duct and the outer casing. This third stream utilizes the radial space more effectively, allowing propulsive efficiency enhancement without proportionally increasing fan diameter or engine weight.
2Productivity
If fan diameter is increased to enhance propulsive efficiency, then propulsive efficiency is improved, but installation difficulty increases
Solution Approach 1:
The segmented three-stream architecture divides the engine into modular flow paths (core stream, first bypass stream, second bypass stream) that can be independently designed and installed. This modularity simplifies installation by allowing each stream's components to be positioned and configured separately, reducing overall installation complexity despite the enhanced propulsive efficiency.
Solution Approach 2:
By utilizing the radial annular space for the second bypass stream, the design achieves enhanced propulsive efficiency without increasing the axial length or overall engine footprint, thereby maintaining ease of installation in standard engine bays without requiring complex modifications.
3Productivity
If conventional two-stream design is used, then device complexity is low, but propulsive efficiency is limited
Solution Approach 1:
The airflow is divided into three distinct streams with separate control mechanisms: core stream through the combustor, first bypass stream around the core, and second bypass stream in the outer annular passage. This segmentation enables independent optimization of each stream's contribution to thrust, improving overall propulsive efficiency while maintaining manageable complexity through systematic design.
Solution Approach 2:
The patent incorporates variable geometry components including adjustable guide vanes and controllable duct configurations that allow dynamic adjustment of the three streams' flow rates and directions. This dynamic control optimizes propulsive efficiency across different operating conditions while the modular architecture keeps the complexity manageable through standardized control systems.
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 design maintains high propulsive efficiency, reduces weight, and addresses thermal management issues, facilitating rapid down-selection of suitable engine configurations and avoiding late-stage redesigns.
Implementation Method 1
The engine includes a heat exchanger in thermal communication with the third stream
Data Source
AI summary
A gas turbine engine includes a turbomachine having a compressor section, a combustion section, and a turbine section arranged in serial flow order. The turbomachine defines an engine inlet to an inlet duct, a fan duct inlet to a fan duct, and a core inlet to a core duct. The primary fan is driven by the turbomachine, and a secondary fan is located downstream of the primary fan within the inlet duct. One or more actuation devices operably associated with the fan duct, the one or more actuation devices actuable to increase or decrease an exit area of the fan duct.