Sinuous Tube Air Cooler for Gas Turbine Bypass
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Solution Overview
Problem
Existing heat exchangers in gas turbine engines are heavy and inefficient, particularly when using bypass air for cooling, as they can disrupt airflow and are susceptible to foreign object damage, limiting their effectiveness and weight reduction potential.
Innovation Solution
A sinuous tube heat exchanger is positioned along the outer bypass duct, extending downstream of an airflow obstruction, which increases heat transfer efficiency while minimizing foreign object damage risk by utilizing a zig-zag pattern that fits within a smaller radial span, allowing for longer tube lengths in a limited area and leveraging turbulence for enhanced heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a straight tube heat exchanger is used in the bypass flow path, then heat transfer efficiency is reduced, but the tube is more susceptible to foreign object damage and requires larger radial span
Solution Approach 1:
The patent applies a sinuous (curved/wavy) tube configuration instead of a straight tube. The sinuous portion extends along the outer bypass duct with multiple bends, increasing the tube length that can be accommodated within the available radial span. This curvature allows the tube to leverage turbulence in the bypass flow for enhanced heat exchange while fitting within a smaller radial envelope, thereby improving both heat transfer efficiency and foreign object damage resistance.
Solution Approach 2:
The patent transitions from a straight linear tube arrangement to a three-dimensional sinuous configuration that exploits the circumferential dimension around the engine core. The sinuous tube winds through the bypass flow path in a complex spatial pattern, maximizing heat transfer surface area within the limited radial space available in the bypass duct, thus resolving the contradiction between heat transfer efficiency and spatial constraints.
2Productivity
If the tube extends further into the bypass flow path to increase heat transfer, then heat transfer efficiency improves, but foreign object damage risk increases
Solution Approach 1:
The sinuous tube configuration allows the heat exchanger to achieve extended heat transfer surface area through curvature rather than linear extension. The wavy pattern enables the tube to remain within a confined radial region while still providing sufficient heat transfer area, avoiding exposure to high-velocity foreign objects in the main bypass flow path.
3Productivity
If a longer tube is used to increase heat transfer surface area, then heat transfer efficiency improves, but the radial span required increases
Solution Approach 1:
The sinuous tube uses multiple bends and curves to pack a longer tube length into a smaller radial footprint. By winding the tube in a compact sinuous pattern rather than extending it linearly, the design achieves extended heat transfer surface area while maintaining a compact radial profile that fits within the bypass duct constraints.
Solution Approach 2:
The sinuous tube configuration effectively nests the tube length within the available radial space by creating a compact, space-efficient geometry. The tube folds back on itself in a controlled manner, maximizing the use of available volume and achieving long heat transfer path length without proportionally increasing the radial envelope.
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 sinuous tube design enhances heat transfer efficiency by up to 20% and reduces foreign object damage risk, achieving effective cooling while maintaining structural integrity and reducing weight, thus improving engine performance and efficiency.
Implementation Method 1
the sinuous portion configured for exchanging heat between a fluid circulating in the tube and air circulating in the bypass flow path during operation of the turbofan engine
Implementation Method 2
leveraging turbulence for enhanced heat exchange
Data Source
AI summary
A turbofan engine comprising an outer bypass duct, an annular bypass flow path between the outer bypass duct and a core engine, an engine component forming an airflow obstruction adjacent the outer bypass duct, an air cooler having a tube, the tube having at least a sinuous portion extending in the annular bypass flow path, the sinuous portion extending along the outer bypass duct, downstream of the airflow obstruction, the sinuous portion configured for exchanging heat between a fluid circulating in the tube and air circulating in the bypass flow path during operation of the turbofan engine.