Industry: Space Technology
Product: Injector Head
What Are Injector Heads and Why 3D-print Them?
Injector heads are amongst the most complicated and critical components of a rocket engine. They consist of many individual injector elements that ensure a good mixing of propellants as they enter the combustion chamber. Due to their myriad of parts, injector heads are a nightmare for conventional, subtractive manufacturing methods and parts assembly, making them expensive, heavy, and prone to failure.
Advanced metal 3D-printing technology now allows for integrated, single-part designs that are more light-weight and faster to produce. However, current state-of-the-art injector heads do not fully exploit the design freedom that comes with additive manufacturing. This is a consequence of the design/CAD tools that are typically used.
Watch video of one of our injector heads 3D-printed in titanium:
Mass-customizing An Injector Head Through Algorithmic Engineering
At Hyperganic, we create algorithms that automatically generate physical objects. We call this method Algorithmic Engineering. Think of the algorithms as step-by-step instructions for the computer to mimic what an engineer would do. The major difference is that a computer can work tirelessly to resolve a problem at a level of detail that a human engineer could not handle.
To 3D-print the injector head, we went one step further by integrating the concept of mass customization into the design. Why should it be optimal to use the hundreds (or thousands, in the case of the Saturn V’s F1 rocket engine) of the exact same injector elements? In an ideal scenario, the design and performance of every single element is driven by a target performance distribution and its respective position within the injector head’s element array. This is exactly what Hyperganic did.
We 3D-printed our design using both Inconel-718 and copper. If you look closely, you will notice that the inner and outer radii of the injector elements vary across the chamber section. This was done to achieve an optimized temperature distribution and mixing ratio inside the combustion chamber.
To prevent a melt-down of the chamber walls, we designed the injector head such that the temperature will drop slightly towards the walls by deviating from the ideal local fuel-oxidizer mixing ratio. On the other hand, the elements in the middle of the chamber are designed for stoichiometric combustion with higher temperatures and maximum performance output.
Enabling Rapid Iterations and Major Time Savings
In the engineering field, most designs are standardized to the point where they can be reused with minimal manual construction work. However, this also impacts on subsequent design choices! Complex products will never be fully optimized if they are built around a set of pre-existing components as this always results in compromises. We believe that the individual parts should be dictated by the ideal product that we envision – not the other way around.
Using computer algorithms, we can eliminate the manual and laborious workload whilst maintaining the flexibility and shareability of the design. In the case of our injector head, the engineer can easily design the injector element array to achieve the desired distribution (field-driven design). This brings engineers to a whole new level where they can rapidly iterate and optimize the system in just a few minutes.
“Traditionally, engineers wouldn’t take the time to go through and optimize this because it will take them forever. But using algorithms, the engineer can easily optimize the mixing ratio of these ports and they can do it quickly and efficiently.”
Trevor Goforth – Additive & EDM Specialist, Titans of CNC, Inc.
Designing Through Generation Sequence
The video below shows the generation sequence in the Hyperganic Core platform. Step-by-step, the geometry comes alive as the algorithms add more parts to the construction. A parametric model of the injector elements allows us to easily generate countless variants of co-axial swirl injector types. Additional parameters are exposed and can be used to change the overall dimensions of the assembly, the number of combustion chambers, the size of the outer diameter and more.
This way, new variants can be generated within minutes. One of these injector head geometries takes about three minutes to generate. If you are willing to invest 10 minutes, you will get these:
You can learn more about the algorithms in our online curriculum and access the source code on our platform.
The entire injector head algorithm is packaged as one code module. It’s re-usable and readily adjustable for advanced use cases. If you were wondering why we incorporated multiple combustion chambers and a central cooling pipe into our design, here’s the reason:
Despite its complexity, the injector head is just one building block of a much larger, modular rocket engine assembly that we will feature in our next case study. In addition, we are currently onboarding more engineers onto the Hyperganic platform in order to supercharge their design capabilities and enable new innovative solutions. Stayed tuned for more updates!