Shape-Memory Wall Cooling Fins for On-Demand Heat Exchange
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Solution Overview
Problem
Current wall-cooling systems for aircraft turbojets require complex structures and continuous fluid supply to maintain wall temperature, lacking an efficient, automatic cooling mechanism that activates only when the wall reaches critical temperature.
Innovation Solution
A wall-cooling device utilizing thermally-conductive shape-memory alloys that change shape and angle relative to the wall at a specific transition temperature, activating cooling only when the wall reaches this temperature, thereby enhancing heat exchange with an external fluid flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If rows of perforated pipes or tubes are used for cooling the wall, then the cooling effect is provided, but the structure becomes complex and requires a continuous fluid supply system
Solution Approach 1:
The invention extracts the cooling function from a complex continuous system and implements it through simple intermittent action. The cooling parts are taken out as individual discrete elements that can independently activate only when needed, eliminating the requirement for complex piping networks and continuous fluid supply infrastructure.
Solution Approach 2:
The cooling parts are made of shape-memory alloy that automatically responds to wall temperature changes. When the wall reaches critical temperature, the cooling part self-activates by changing its shape to expose the cold face to the outer fluid, and returns to its initial position when the temperature decreases, eliminating the need for external control systems or continuous fluid supply mechanisms.
2Device complexity
If cooling parts are pressed against the wall, then the structure is simple, but the cooling effect is not produced until the wall reaches critical temperature
Solution Approach 1:
The invention changes the physical state and shape of the cooling parts through temperature-dependent phase transformation of the shape-memory alloy. The cooling parts remain in a compressed state at lower temperatures and automatically change their shape when the wall temperature reaches the critical threshold, enabling timely cooling activation without complex sensing or control systems.
Solution Approach 2:
The cooling parts transition from a static pressed position to a dynamic active cooling position based on temperature conditions. The shape-memory alloy enables the cooling parts to automatically adjust their configuration in response to thermal conditions, moving from a low-profile state to an extended cooling state when needed.
3Area of stationary object
If the cooling portion forms a dihedral angle with the wall, then the heat-exchange area is increased, but the structure becomes more complex
Solution Approach 1:
The cooling portion dynamically changes its orientation relative to the wall based on temperature conditions. At normal temperatures, the cooling portion remains parallel to the wall with minimal profile. When the wall reaches critical temperature, the cooling portion rotates to form a dihedral angle (45° to 90°) with the wall, maximizing heat-exchange area with the outer fluid without requiring permanently complex structures.
Solution Approach 2:
The cooling part utilizes spatial transformation by changing from a two-dimensional planar configuration (parallel to wall) to a three-dimensional angled configuration (dihedral angle with wall). This dimensional change enables significant increase in heat-exchange area with the outer fluid while maintaining a compact form when cooling is not active.
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 solution provides a simpler, automatic cooling mechanism that activates only when needed, increasing the heat-exchange area and improving cooling efficiency by altering the shape and angle of the cooling parts relative to the wall and fluid flow, thus effectively regulating the wall temperature without additional mechanical systems.
Implementation Method 1
said part being made of a thermally-conductive shape-memory alloy having a transition temperature T
Implementation Method 2
the cooling effect is produced only when the temperature of the wall to be cooled actually reaches the transition temperature of the thermally-conductive shape-memory alloy as a result of the thermal conduction between the wall and the cooling part
Implementation Method 3
said portion plays the role of cooling fin that increases the heat-exchange area between the wall and the outer fluid
Implementation Method 4
the cooling portions in the active position, give rise to turbulence in the outer stream in immediate proximity with the wall to be cooled, thus increasing the Reynolds coefficient of said flow and thus improving the cooling effect
Data Source
AI summary
The invention relates to a wall-cooling device for cooling a wall (10) having a first face subjected to a heat source and a second face along which an outer fluid flows at a temperature that is less that T in order to maintain said wall at a temperature that is substantially equal to the temperature T.The device comprises at least one cooling part (12) including a fastening portion (14) and a cooling portion (16), said part being made of a thermally-conductive shape-memory alloy having a transition temperature T. The fastener portion is for fastening said device rigidly on the second face (10b) of said wall.The cooling portion is shaped so that it takes up a first position that is substantially parallel to said wall when the temperature of the wall is lower than said temperature T and so that it takes up a second position in which the mean plane of said second portion defines, relative to a plane tangential to said wall, a dihedral angle lying in the range 45° to 90°.