Transpiration Cooling Element with Localized Permeability
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Solution Overview
Problem
Existing cooling devices for effusion or transpiration cooling, such as those used in rocket combustion chambers, face challenges in forming a sufficient cooling fluid film in the start-up area, leading to excessive heat input and potential failure due to insufficient cooling fluid film formation.
Innovation Solution
The cooling device features a terminal partial area with increased cooling fluid throughput per unit area, achieved through higher permeability of the open-pored material or geometric modifications like recesses and gaps between the cooling element and connection element, ensuring a uniform cooling fluid film formation along the cooling surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cooling fluid throughput is increased throughout the entire cooling element to ensure sufficient cooling fluid film formation in the start-up area, then the cooling fluid film can be formed sufficiently, but the cooling fluid consumption increases unnecessarily and overcooling occurs in major areas
Solution Approach 1:
The cooling element is designed with non-uniform cooling fluid throughput distribution, where the start-up area has higher throughput to ensure sufficient cooling fluid film formation, while other areas have lower throughput to avoid overcooling. This local differentiation of cooling fluid flow rates resolves the contradiction between ensuring reliable cooling film formation and minimizing overall cooling fluid consumption.
2Object-affected harmful factors
If the cooling fluid throughput is increased in the start-up area to form sufficient cooling fluid film, then the cooling element is protected from excessive heat input, but the cooling fluid film becomes non-uniform and thicker in other areas leading to overcooling
Solution Approach 1:
The cooling element incorporates spatially varying cooling fluid throughput rates, with the start-up area receiving higher flow rates to prevent excessive heat input, while other areas receive lower flow rates to maintain uniform film thickness and prevent overcooling. This localized optimization of cooling fluid distribution addresses both the heat protection requirement and the uniformity requirement.
3Loss of substance
If a uniform cooling fluid throughput is maintained across the entire cooling element, then the cooling fluid consumption is optimized, but the cooling fluid film cannot form sufficiently in the start-up area leading to potential failure
Solution Approach 1:
The cooling element is designed with differentiated cooling fluid throughput rates across different regions. The start-up area has elevated throughput to ensure reliable cooling fluid film formation, while other areas have reduced throughput to maintain overall cooling fluid consumption efficiency. This non-uniform distribution resolves the contradiction between localized reliability requirements and overall resource efficiency.
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
This design effectively prevents excessive heat input by ensuring a sufficient and uniform cooling fluid film is formed across the cooling surface, even under extreme conditions, without overcooling other areas or increasing cooling fluid consumption.
Implementation Method 1
This cooling fluid film absorbs part of the heat supplied or generated by the gas flow and protects the cooling element and the structures underneath from excessive heat input
Implementation Method 2
the cooling fluid emerges from a large number of microporous openings in the open-pore material and can therefore form a homogeneous, flat cooling fluid film on the cooling surface
Implementation Method 3
the cooling element being formed from an open-pored material and a cooling fluid being able to be passed through the cooling element transversely to the cooling surface
Implementation Method 4
Effusion or transpiration cooling is extremely effective because the cooling fluid emerges from a large number of microporous openings in the open-pore material
Implementation Method 5
In the boundary layer that forms between the cooling fluid film and the gas flow, part of the cooling fluid is entrained in the direction of the main flow direction of the gas flow
Implementation Method 6
part of the cooling fluid is entrained in the direction of the main flow direction of the gas flow
Data Source
Figure 1~3
Figure 4~6
AI summary
The present invention relates to a cooling device (30, 40, 50, 60) for effusion or transpiration cooling, comprising a cooling element (12) having a cooling surface (14) facing a gas stream (16), wherein the cooling element (12) is made of an open-pore material and wherein a cooling fluid can be passed through the cooling element transversely to the cooling surface (14) and forms a cooling fluid film (22) on the cooling surface (14). In order to provide such a cooling device (30, 40, 50, 60) in which a sufficient cooling fluid film (22) can already be formed in the starting region of the cooling element (12), it is proposed that the cooling element (12) comprises a terminal sub-region (32) in the direction of flow of the gas stream (16) in which the throughput of cooling fluid per unit area of the cooling surface (14) is increased compared to the other regions of the cooling element (12).