Heat Exchanger Mixing Chambers for Boundary-Layer Disruption
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Solution Overview
Problem
Existing aircraft engine heat exchangers face inefficiencies due to boundary layer buildup, which reduces heat transfer as fluids flow through conduits, leading to decreased performance over time.
Innovation Solution
Incorporation of a mixing chamber with protrusions, such as helicoidally or annular designs, within the heat exchanger to disrupt boundary layers and enhance turbulence, combined with features like convergent and divergent sections and swirl-inducing apertures to improve mixing and heat exchange efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional heat exchanger conduits are used without mixing chambers, then the structure is simple and easy to manufacture, but boundary layer buildup reduces heat transfer efficiency over time
Solution Approach 1:
The conduit is segmented into multiple sections by inserting mixing chambers at intervals along the flow path. Each mixing chamber independently disrupts the boundary layer in its local section, preventing the continuous boundary layer buildup that occurs in conventional smooth conduits. This segmentation maintains heat transfer efficiency throughout the entire conduit length while keeping each individual mixing chamber relatively simple in design.
2Reliability
If mixing chambers with protrusions are added to disrupt boundary layers, then heat transfer efficiency is enhanced, but the device complexity increases
Solution Approach 1:
The mixing chambers introduce dynamic flow disruption through protrusions that create turbulence and mix the boundary layer with the core flow. This dynamic interaction between the protrusions and the flowing fluid continuously renews the thermal boundary layer, enhancing heat transfer efficiency without requiring complex external control systems or moving parts.
3Reliability
If protrusions extend across the flow direction in the mixing chamber, then turbulence is enhanced and boundary layer disruption is improved, but pressure drop increases
Solution Approach 1:
The protrusions extend partially across the flow direction rather than completely blocking it, creating sufficient turbulence to disrupt the boundary layer while leaving enough open flow area to limit pressure drop. This partial action approach achieves the necessary flow disruption for enhanced heat transfer without excessive resistance to the overall fluid flow.
4Reliability
If the mixing chamber has a large flow circulating area, then mixing volume is sufficient, but the chamber size increases the overall heat exchanger footprint
Solution Approach 1:
The mixing chamber utilizes the radial dimension by having protrusions extend from the peripheral wall toward the center, creating effective mixing in three-dimensional space. This vertical/radial utilization of space allows sufficient mixing volume to be achieved within a compact axial footprint, reducing the overall size of the heat exchanger while maintaining effective mixing capability.
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 significantly enhances heat transfer efficiency by mixing boundary layer and core flows, reducing pressure drop, and maintaining effective heat exchange across the length of the conduits.
Implementation Method 1
protrusions extending from the peripheral wall into the mixing volume, the protrusions extending around the central axis and across a direction of the flow through the mixing chamber
Implementation Method 2
boundary layer flows and core flows; mixing the boundary layer flows with the core flows
Implementation Method 3
a heat exchanger for exchanging heat with a fluid flowing through the aircraft component
Implementation Method 4
first conduits in fluid communication with the fluid circuit and having first conduit inlets and first conduit outlets, the first conduits being in heat exchange relationship with the second fluid
Data Source
AI summary
A system for an aircraft engine, has: an aircraft component; and a heat exchanger having: a housing defining a first inlet, a first outlet, a second inlet, and a second outlet; first conduits within the housing, the first conduits fluidly connecting the first inlet to the first outlet; one or more second conduit within the housing, the one or more second conduits fluidly connecting the second inlet to the second outlet, the one or more second conduit in heat exchange relationship with the first conduits; a mixing chamber intersecting two or more of the first conduits, the mixing chamber having a peripheral wall extending around a mixing volume and a central axis; and protrusions extending from the peripheral wall into the mixing volume, the protrusions extending around the central axis and across a direction of the flow through the mixing chamber.