Variable Geometry Heat Exchanger for Gas Turbine Drag Reduction
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Solution Overview
Problem
Conventional heat exchanger assemblies in gas turbine engines are overdesigned for ground idle and top of climb conditions, leading to increased drag and specific fuel consumption during cruise conditions, where they are not needed, and fail to efficiently manage heat transfer fluid cooling across varying flight phases.
Innovation Solution
A variable geometry surface cooler with a passive automatic retraction and extension system, utilizing a thermal actuation component like shape memory alloys, adjusts the geometry of cooling fins in response to temperature changes to optimize heat exchange and minimize drag during different flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional heat exchanger assemblies are overdesigned for ground idle and top of climb conditions, then sufficient cooling is provided during high temperature conditions, but aerodynamic drag and specific fuel consumption increase during cruise conditions
Solution Approach 1:
The heat exchanger apparatus employs variable geometry cooling fins that can dynamically adjust their configuration between extended and retracted positions. During ground idle and top of climb conditions, the fins extend to maximize heat exchange surface area and provide sufficient cooling. During cruise conditions, the fins retract to minimize aerodynamic drag and reduce specific fuel consumption. This dynamic adaptability resolves the contradiction between maintaining cooling effectiveness and reducing energy loss.
Solution Approach 2:
The apparatus changes the geometric parameters of the cooling fins based on operating conditions. The fin configuration transitions from an extended state with large surface area for maximum heat dissipation to a retracted state with reduced surface area for minimum drag. This parameter change allows the system to optimize performance across different flight phases, addressing the contradiction between cooling requirements and energy efficiency.
2Temperature
If conventional heat exchanger assemblies are overdesigned for ground idle and top of climb conditions, then sufficient cooling is provided during high temperature conditions, but aerodynamic drag increases during cruise conditions
Solution Approach 1:
The cooling fins are designed with dynamic adjustability, allowing them to transition between extended and retracted positions. During ground idle and top of climb conditions when cooling demand is high, the fins extend to provide maximum heat dissipation surface area. During cruise conditions when cooling demand is lower, the fins retract to minimize their exposure to the airflow, thereby reducing aerodynamic drag. This dynamic behavior resolves the contradiction between maintaining cooling effectiveness and minimizing drag.
Solution Approach 2:
The geometric parameters of the heat exchanger, specifically the fin configuration, are changed based on operating conditions. The system transitions from a high-surface-area configuration that maximizes heat exchange to a low-surface-area configuration that minimizes aerodynamic interference. This parameter change enables the system to adapt to varying flight conditions, resolving the contradiction between cooling effectiveness and drag reduction.
3Device complexity
If conventional heat exchanger assemblies maintain fixed geometry, then structural simplicity is achieved, but the system fails to efficiently manage heat transfer fluid cooling across varying flight phases
Solution Approach 1:
The heat exchanger apparatus incorporates variable geometry cooling fins that can dynamically adjust their configuration in response to changing flight conditions. The fins transition between extended and retracted positions based on thermal demands during different flight phases. This dynamic capability enhances adaptability while maintaining relatively simple structural implementation through passive thermal actuation mechanisms.
Solution Approach 2:
The variable geometry mechanism is actuated passively by thermal conditions themselves, without requiring external energy sources or complex control systems. The thermal environment directly drives the fin configuration changes, allowing the system to adapt to varying flight conditions autonomously. This self-service approach maintains structural simplicity while achieving high adaptability.
4Adaptability or versatility
If passive automatic retraction and extension system is implemented, then adaptability to temperature changes is improved, but device complexity increases
Solution Approach 1:
The passive automatic retraction and extension system utilizes thermal actuation components that respond directly to temperature changes in the heat transfer fluid. The system actuates itself based on thermal conditions without requiring external energy sources, control systems, or complex mechanisms. This self-service approach achieves high adaptability to temperature changes while minimizing the increase in device complexity.
Solution Approach 2:
The patent replaces complex mechanical actuation systems with thermal actuation mechanisms. Instead of using motors, sensors, and control systems to adjust fin configuration, the design uses materials and structures that respond directly to thermal conditions. This substitution of mechanical systems with thermal-based actuation achieves adaptability while keeping the system relatively simple.
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 system maintains effective cooling while reducing aerodynamic drag and specific fuel consumption by automatically adjusting fin geometry based on temperature, ensuring efficient heat transfer across varying flight conditions without the need for external energy sources.
Implementation Method 1
The thermal actuation component is responsive to a change in temperature of at least one of the heat transfer fluid and a cooling fluid flow so as to actuate a change in a geometry of the surface cooler
Implementation Method 2
The heat transfer fluid is in a heat transfer relation on an interior side of said one or more fluid flow channels
Implementation Method 3
Heat is typically rejected from the fluid to air by heat exchanger assemblies
Data Source
Figure 1
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Figure 4~5
AI summary
A heat exchanger apparatus (54) including a surface cooler (56) and a passive automatic retraction and extension system coupled to the surface cooler (56). The surface cooler (56) having disposed therein one or more fluid flow channels (58) configured for the passage therethrough of a heat transfer fluid to be cooled. The heat transfer fluid in a heat transfer relation on an interior side of said one or more fluid flow channels (58). The surface cooler (56) including a plurality of fins projecting from an outer surface thereof. The passive automatic retraction and extension system including a thermal actuation component (104, 154, 204, 254) responsive to a change in temperature of at least one of the heat transfer fluid and a cooling fluid flow so as to actuate a change in a geometry of the surface cooler (56). Further disclosed is an engine including the heat exchanger apparatus (54).