Three-Stream Turbofan Layout for Fan Diameter and Thermal Constraints
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Solution Overview
Problem
Conventional turbofan engine design faces challenges in increasing fan diameter for improved propulsive efficiency, leading to installation difficulties, weight issues, and thermal demands, while maintaining desired overall efficiency.
Innovation Solution
A three-stream gas turbine engine design incorporating a primary and secondary fan, with a third stream airflow, utilizing variable geometry components and heat exchangers to optimize airflow ratios and thermal management, enhancing propulsive efficiency and reducing weight and packaging concerns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fan diameter is increased to improve propulsive efficiency, then propulsive efficiency is improved, but installation difficulty increases, weight increases, and thermal demands increase
Solution Approach 1:
The patent divides the single fan system into multiple fans (first fan and second fan) that work together to generate thrust. The first fan is driven by the turbomachine while the second fan is driven by an independent motor, allowing distributed weight and improved propulsive efficiency without excessive weight concentration in one component.
Solution Approach 2:
The patent introduces a vertical dimension to the airflow by having the second fan draw air from below the engine and discharge it upward, while the first fan handles horizontal airflow. This three-dimensional airflow configuration improves propulsive efficiency without requiring a single oversized fan, thus reducing weight and installation complexity.
2Productivity
If fan diameter is increased to improve propulsive efficiency, then propulsive efficiency is improved, but installation difficulty increases
Solution Approach 1:
The patent divides the fan system into multiple smaller fans (first fan and second fan) rather than one large fan. This segmentation allows for more compact engine packaging and easier installation in aircraft, while maintaining high propulsive efficiency through the combined thrust of multiple fans operating in different airflow directions.
Solution Approach 2:
The patent utilizes vertical airflow dimension with the second fan drawing air from below and discharging upward, creating a compact three-dimensional airflow pattern. This reduces the horizontal footprint of the engine, making it easier to install in aircraft with limited space, while maintaining high propulsive efficiency.
3Productivity
If fan diameter is increased to improve propulsive efficiency, then propulsive efficiency is improved, but thermal demands increase
Solution Approach 1:
The patent divides the air intake into separate streams handled by different fans. The first fan handles ambient air intake while the second fan draws air from below the engine. This segmentation allows for distributed thermal management, reducing the thermal load on any single component and improving overall propulsive efficiency without excessive thermal demands.
Solution Approach 2:
The patent introduces a heat exchanger as an intermediary component in the second air stream path. The heat exchanger pre-cools the air drawn from below the engine before it enters the second fan, reducing thermal demands on the system while maintaining high propulsive efficiency through optimized airflow temperatures.
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 or improves propulsive efficiency by balancing airflow ratios, addressing weight and thermal management, and facilitating rapid down-selection of suitable engine configurations.
Implementation Method 1
a heat exchanger in thermal communication with the first air stream and the second air stream
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, a booster located downstream of the secondary fan and comprising a booster rotor blade 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, and a flow blocker located at the lower fan duct inlet and movable from an open position to a closed position, wherein, in the closed position, the flow blocker blocks a flow through at least a portion of the lower fan duct inlet.