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Additive Manufacturing enables optimized fluid dynamics

For many years, part complexity has had a ceiling. Past a certain point, conventional production techniques could no longer deliver complex designs cost-effectively, or in some cases, at all. Today, engineers are setting previous limitations aside to produce sophisticated, high-value components that are taking teams farther than they have ever gone.

For example, engineers at the European Organization for Nuclear Research (CERN) needed to cool the detection area of the Large Hadron Collider to -40˚C in order to preserve particle reactions for study. This area is 140 meters long and less than 2 millimetres wide, and the heat that must be dissipated is extreme. They were able to do it with an additive manufacturing solution.

Faced with a different set of challenges, the German Aerospace Center (Deutsches Zentrum für Luft-und Raumfahrt, or DLR) was on a mission to increase performance and reduce weight on a coaxial injector head for a satellite launch vehicle. By choosing an additive manufacturing approach, both needs were answered.

Additive Manufacturing makes it possible to isolate and solve challenging aspects of part performance without the limitations of conventional manufacturing. This means manufacturability and design freedom are no longer at odds, allowing you to bring new functionality to parts and systems in the form of reduced assembly for production lines, less weight in components, greater reliability due to reduced connection points, and organic channel designs, just to name a few. But, when transitioning to Additive Manufacturing, it is imperative to switch to a design for additive manufacturing (DfAM) mindset.

The advantages of Additive Manufacturing are clear when it comes to high-value fluid dynamics applications, such as heat exchangers, propulsion systems, fuel injectors, manifolds.

Heat Exchangers

Heat exchangers are parts used to manage thermal energy within a larger system. These components have a tremendous impact on the systems in which they are required, so optimizing their functionality and efficiency is critical. Additive Manufacturing production can improve the performance of a wide range of applications requiring heat exchange, including:

  • Electronic devices
  • Cold plates
  • Electric motor cooling
  • Molds and tooling with conformal channels
  • Integrated cooling components

When designing a heat exchanger for production using traditional manufacturing, the size and shape of producible cooling channels are limited. Additive Manufacturing, on the other hand, frees design limitations making it possible to build channels within channels for increased counter-flow, surface area, and thermal exchange; or introduce roughness on the channel’s interior surface to induce turbulence. AM also makes it possible to manufacture designs generated by finite element software packages with little to no concessions. Such designs typically have very complex shapes to maximize surface area, and thus heat exchanged, within a constrained space. Additive Manufacturing’s ability to print complexly shaped, thin walls allows for significant increases in thermal energy transfer, without creating the weak points seen in traditional manufacturing.

For certain heat exchange applications, accommodating a constrained space also poses a challenge. In these instances, greater flexibility to produce organic shapes with AM and the ability to consolidate assemblies into a single part are great advantages.

Propulsion Systems and Fuel Injectors

Propulsion and rocket systems are responsible for setting objects into motion. These systems are highly complex and require precision, reliability, and optimized weight to ensure success, safety, and efficiency. An integral part of any propulsion system is the fuel injector. Conventional manufacturing for these kinds of components limits injector designs to fairly simple structures. By adopting AM, it is possible to produce a higher number of more complex internal paths for fluid flow to introduce better mixing efficiency. AM design strategies can also reduce part weight, increase the performance of the larger system while maintaining manufacturability, and reduce assemblies of 50 or more parts to a single piece.

For example, this liquid rocket engine injector was developed using AM by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, or DLR). AM was chosen to integrate cooling channels for increased performance and to reduce parts count for reduced weight, increased reliability, and improved fuel efficiency.

The rocket engine injector developed by the German Aerospace Center (DLR – Deutsches Zentrum für Luft- und Raumfahrt)
Injector head flow volumes: blue = LOX; orange = kerosene; red = film layer; green = transpiration cooling
A view inside the injector head shows the complexity enabled by metal 3D printing.

By using metal 3D printing, DLR was able to drastically change the design methodology of its coaxial injectors and avoid 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 sites to alleviate related quality control measures and improve system performance.

Fluid Manifolds

Take out weight and improve performance by eliminating stagnant areas. Although conceptually simple, most traditional manufacturing techniques are not well suited to make manifolds. Traditionally manufactured fluid manifolds tend to include 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. Whether you work in high-value industrial equipment or high speed, high-performance motorsports, better-performing fluid manifolds should be on your radar. By transitioning to AM production, it is possible to not only take out the excess weight that may be impacting system performance, but also to improve the performance of the component itself by eliminating stagnant areas and better addressing function through form.

Using AM it is possible to avoid many of the limitations imposed by conventional manufacturing processes, and begin the design process with your optimal theoretical shape. Taking this approach, it is possible to reduce the overall footprint, material use, and weight by using more organic shapes that improve performance by eliminating sharp corners and stagnant zones.

The Benefits of AM

The benefits of AM for fluid flow applications are numerous, intertwined, and frequently motivated by a combination of enhancements to performance, economics, and reliability. Value cross-over of using AM to produce advanced fluid flow applications.

IMPROVED FLOW EFFICIENCY – Additive Manufacturing enables a number of design strategies that make it possible to improve the flow performance of your part or system, including the use of organic shapes to eliminate stagnant zones.

IMPROVED PEAK COOLING – Depending on the design strategy and post-processing workflow, Additive Manufacturing can promote turbulence in applications like heat exchangers where turbulence can increase thermal transfer, or limit turbulence in applications like fluid manifolds where the goal is to move fluid without losing pressure. Peak cooling is also improved by the ability to print thin walls, increase the surface-to-volume ratio with more complex designs, and increase reliability due to the absence of welds or gaskets.

REDUCED WELDS AND ASSEMBLY – The ability to produce complex geometries in a single build invites new opportunities to eliminate or reduce assembly by designing and producing former assemblies as consolidated or monolithic parts. This design strategy frequently comes with a cascade of benefits, including reduced production time, reduced production cost, higher part reliability due to fewer or no weak points, and a reduction in the final weight.

IMPROVED COOLING UNIFORMITY – With Additive Manufacturing it is possible to build cooling channels that follow the contours of your part. Known as conformal cooling lines, these enable higher control over the performance of your system. In mold making applications, improved cooling uniformity can lead to faster cycle times and greater productivity.

SPACE UTILIZATION – Additive Manufacturing production increases your ability to create functional components that fit within the confines of a larger system.

WEIGHT REDUCTION – Having lighter parts is a frequent goal for components in fast-moving systems, where part performance, fuel efficiency, and operational costs are impacted by the total mass. AM enables several design strategies that reduce overall part weight without impacting strength or performance, including the integration of lattice structures, topological optimization, thinner walls, and part consolidation.

From “Advanced Manufacturing for Optimized Fluid Dynamics” by 3D Systems – Additive Manufacturing Solutions (https://www.3dsystems.com/)