Asymmetric Augmentation in Cast Plate Heat Exchangers
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Solution Overview
Problem
Turbine engine heat exchangers face high mechanical stresses due to thermal gradients, which can exceed material and assembly capabilities, especially at joints where temperature differences are significant, leading to potential structural failures as operational temperatures and pressures increase.
Innovation Solution
A cast plate heat exchanger with varying augmentation feature densities on its surfaces to tailor thermal transfer and reduce mechanical stresses, where the density of augmentation features on the outer surface is greater than in the internal passages, particularly in regions adjacent to high-stress joints, allowing for more uniform thermal gradients and reduced stress concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform augmentation feature density is applied across all surfaces, then manufacturing is simplified, but thermal gradients and mechanical stresses remain unbalanced leading to structural failures
Solution Approach 1:
The patent applies different densities of augmentation features to different regions of the heat exchanger surfaces. Specifically, the first surface has a lower density of augmentation features while the second surface has a higher density, creating local quality variations that balance thermal gradients and reduce mechanical stresses at critical locations such as joints and corners.
Solution Approach 2:
The patent introduces asymmetric application of augmentation features where the density distribution is not uniform across the heat exchanger. The first surface has lower augmentation feature density compared to the second surface, creating an asymmetric configuration that compensates for unbalanced thermal gradients and stress distributions inherent in the heat exchanger geometry.
2Productivity
If augmentation feature density is increased to enhance thermal transfer, then thermal efficiency improves, but mechanical stresses increase exceeding material capabilities
Solution Approach 1:
The patent strategically distributes augmentation features with varying densities across different surfaces to locally optimize thermal transfer while managing stress concentrations. The lower density on the first surface and higher density on the second surface create a balanced thermal management approach that prevents excessive stress anywhere in the structure.
Solution Approach 2:
The patent changes the density parameter of augmentation features across different regions. By varying the density from the first surface to the second surface, the patent optimizes thermal transfer efficiency while controlling mechanical stresses within material limits, achieving a balance between thermal performance and structural integrity.
3Productivity
If higher operational temperatures and pressures are used to improve engine efficiency, then engine performance improves, but stresses on heat exchanger structure exceed material and assembly capabilities
Solution Approach 1:
The patent applies local quality variations in augmentation feature density to specifically address high-stress regions. By having lower density on the first surface and higher density on the second surface, the patent creates a stress-balanced configuration that enables operation at higher temperatures and pressures without exceeding material capabilities.
Solution Approach 2:
The patent incorporates augmentation features that preemptively reduce stress concentrations before they can cause failure. The asymmetric density distribution is designed in advance to compensate for the increased thermal and mechanical loads, providing a cushioning effect that allows higher operational conditions without exceeding material limits.
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 tailored augmentation feature density reduces mechanical stresses and enhances thermal transfer efficiency, improving the structural integrity and performance of heat exchangers under increased operational conditions.
Implementation Method 1
The flow paths are defined by a combination of plates and fins that are arranged to transfer heat from one flow to another flow
Implementation Method 2
Thermal gradients present in the sheet material create stresses that can be very high in certain locations
Data Source
AI summary
A cast plate heat exchanger includes an inner surface of a passage with a first group of augmentation features with a first density across the inner surface. An outer surface includes a second inlet end and a second group of augmentation features arranged with a second density across the outer surface. The first density and second density of augmentation features are located in a targeted manner to reduce thermal stresses.