In July, the winners of the 3D Hubs Student Grant were announced, demonstrating an impressive range of talent and ingenuity from students everywhere. One of the Student Grant finalists was a team called JetX, composed of a group of aerospace engineering students. Currently those students are working with Rolls Royce to create the world’s first functional 3D printed jet engine model.
The project was begun at the University of Glasgow in 2013. Chris Triantafyllou, the President and Founder of JetX, realized that there was a need for more hands-on activity and less textbook learning to get people to be more engaged with the subject of aerospace engineering. In addition, he noted two skills – design for assembly and simulation analysis – that engineers would need in the future, but that they had no way to gain direct experience with. So JetX began the project of building the 3D printed engine model.
More than 50 engineers have been working on the functional X-plorer 1 model, which is 75 cm long with a span diameter of 27 cm and a weight of 8.1 kg. The high-bypass turbofan model contains more than 965 3D printed parts, 300 fasteners and 10 integrated sensors. The whole thing has been built from scratch, with each piece modeled in line with current aero-propulsion theories.
“The first step in optimizing the design is to perform computational analyses to investigate how the flow changes throughout the engine, as well as the effect that specific forces and loading conditions have on the parts,” said Triantafyllou. “When several designs are available for one part, CFD analyses are performed with tools that include Solidworks Flow Simulation, ANSYS Fluent & Star CCM+ on single stators, rotors or multi-stage segments to assess which one performs the best.”
The team also carries out Finite Element Analyses to identify high stress concentrations and ascertain whether failure is likely under different loading conditions. Even on a model of the size the team is building, centrifugal forces can be strong, and failure scenarios are modeled to assess whether an impact would be contained.
The 3D printed parts are made from a variety of materials, including PLA, ABS, Nylon and PETG, among others. The shortest print was only 7 minutes, with the longest lasting more than 58 hours. According to Triantafyllou, 3D printing was used as CNC machining or other technologies would have been too expensive.
“The transition from CAD to part is simpler and the amount you spend goes a long way with 3D printing especially when using an FFF 3D printer,” he said.
In addition, 3D printing meant that the team could easily redesign and test new parts when needed. For example, a shaft connection proved itself to be too weak, so they redesigned and reprinted the part until it had the needed strength.
“It took 21 prototypes and only 7 days to get to the part we needed, using another manufacturing method would [have] meant months and the cost would be £1,000’s or even £10,000’s,” said Triantafyllou.
Inside the Xplorer-1 is a custom-built Engine Monitoring System (EMS) in which everything was developed by the team, including the PCB designs, purpose built software and user interface. The EMS consists of wireless transceivers, 2 mbed micro-controllers, temperature sensors, differential pressure sensor, LED rotational speed sensors, a vibration sensor and an airspeed sensor. The fireless engine works when compressed air is passed through it, at which point the students can take measurements with the numerous sensors. They can then see the performance of the engine both electronically and right in front of them, which leads to more parts and iterations and helps the students learn the full process of engineering such a piece of machinery. The students will continue to improve the engine in both its performance and its capability of providing data; Rolls Royce is offering advice on industry practices to try to get the engine’s iterations as close to the real process as possible.
Triantafyllou would like to see the project expand, possibly into a future competition in which universities compete to build the most efficient engine.
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