For many years now, engineers have faced a wall when it comes to optimising fluid dynamics systems.
While there is software available that enables engineers to simulate ideal designs, the limitations of traditional manufacturing techniques have often prevented engineers from bringing those complex simulations and designs to life — particularly in a way that remains cost-effective.
However, what we’re starting to see is that 3D printing, also known as additive manufacturing (AM), is helping engineers to innovate and break through these walls. Through the power of AM, we’re seeing those complex designs turned into reality, leading to big improvements in the performance, reliability, and economics of fluid dynamics systems.
While AM techniques can solve many of the limitations posed by conventional manufacturing, utilising AM to its full potential also requires a mindset shift. To fully understand the gains and improvements possible through AM with regards to fluid dynamics systems, it helps to look at real-world applications.
The European Organisation for Nuclear Research (CERN) turned to AM to advance particle detection in its Large Hadron Collider experiments. To preserve particle reactions for study, the research team needed to cool the detection area to -40˚C, which was complicated by several factors including limited space in which the cool-bars need to fit, amount of heat to dissipate within a confined space, the need for temperature uniformity over the length of the photo-detection strip, and flatness requirements to preserve detector efficiency and resolution.
The team began with its ideal part design but the required wall thickness was a particular challenge, as it could not be machined for the length (263mm) of the part. Through collaboration with 3D Systems’ Application Innovation Group, the team designed and produced 600 3D-printed titanium cool-bars (more than 150m of cooling channel) that achieved the required 0.25mm wall thickness with reliable leak-tightness and challenging flatness with a 50 micron tolerance.
Propulsion systems and fuel injectors
The Smile project, a consortium comprising of 14 European partners, received Horizon2020 funding from the European Commission to develop a small, innovative rocket. Within the project, the German Aerospace Center (DLR) focused on liquid propulsion to offer a reliable, high performing, re-ignitable engine with throttling capabilities. The engine relied on a highly complex injector to maximise cooling of the combustion chamber, thereby defining a clear necessity to integrate AM design features.
By using metal AM, DLR drastically changed the design methodology of its coaxial swirl injectors, integrating two unique cooling functionalities and avoiding the need for multiple subcomponents, which contributed to significantly lowered production time and cost. A parts count reduction from 30 to one led to a final weight reduction of 10%, and removed known points of failure at fastening locations to alleviate related quality control measures and improve system performance. Overall, the consortium reached the targeted TRL6 level, partly because the shortened manufacturing cycle allowed for an additional iteration.
Fluid manifolds are integral to industries ranging from high-value industrial equipment to high-speed, high-performance motorsports. Traditionally-manufactured fluid manifolds cannot avoid sharp corners, which are disruptive to fluid flow and prone to stagnant zones within the part, leading to pressure loss. They are also typically large in volume and contribute excess weight.
Using AM rather than conventional tooling methods allows engineers to begin the design process with the optimal theoretical shape. Taking this approach it is possible to reduce the overall footprint, material use and weight by using more organic shapes, which improve performance by eliminating sharp corners and stagnant zones.
Speeding up microfluidics
Microfluidic systems process or manipulate small amounts of fluids, using channels ranging in size from tens to hundreds of microns. Given these small dimensions and the delicacy of the fluids involved, traditional fabrication methods have been slow, expensive, and require labour-intensive cleanroom processes.
The use of AM and biocompatible materials introduces far greater speed and design complexity to microfluidics, making it possible to dramatically increase performance and production capabilities. The Imperial College London Lacewing project for pathogen detection, for example, used the Figure 4 Standalone 3D printer and biocompatible production-grade materials to prototype and produce microfluidics and functional components for its lab-on-chip platform. Each Lacewing microfluidic cartridge is roughly 30mm by 6mm by 5mm, printed in 10 micron layers.
When transitioning to AM, it is imperative to switch to a design with an AM mindset. The technique makes it possible to isolate and solve challenging aspects of part performance without the limitations of conventional manufacturing, allowing engineers to bring sophistication to parts and systems with new functionality.
When integrating AM into a production workflow, it’s important to remember solutions include not only materials, hardware and software, but engineering know-how and a breadth and depth of expertise. Engineering services can offer tremendous value to teams looking to develop, validate and scale AM workflows. Seeking expert guidance in the early design phase can have positive impacts on both timelines and outcomes.
Leading manufacturers are increasingly relying on AM to improve performance, economics and reliability. Engineers are now able to create high-value parts without the limitations of traditional technologies, fuelling innovation and disrupting industries.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.