MOTOR: Multi-ObjecTive design Optimization of fluid eneRgy machines

Between 2015 and 2018 Matthias Möller coordinated the 4.3 million euro H2020 MOTOR project, aimed at optimising the design process for fluid energy machines. With the project now successfully behind him, he looks back with satisfaction on the past couple of years. “I learned a lot about project management at a large scale and everything involved with that, from group dynamics to legal issues”, he says.

Assistant Professor Matthias Möller holds up a mock-up of a twin-screw rotary compressor: “Look, these two rotors rotate to compress the air. They are used in environments where a high flow rate and a stable flow of compressed air is needed, like in the food industry for example, or in a cleanroom”, he explains. “Because of the complex shapes of the rotors, the airflow around them is continually changing.” However, the efficiency of such devices depends on their geometry, so to optimise their design you have to be able to simulate that airflow as accurately as possible.

It is a subject Möller is familiar with: “I already worked on this at my alma mater, TU Dortmund University, but we weren’t getting very far with standard simulation techniques like finite element analysis”, he says. After joining the Delft Institute of Applied Mathematics (DIAM) in 2013, he decided on using a relatively new numerical method, isogeometric analysis (IGA), that integrates finite element analysis with Computer Aided Design (CAD). Coupling these increases the efficiency of design and development processes.

Getting funding proved difficult

Möller initially suggested a joint project with the Faculty of Mechanical Engineering of TU Dortmund University to look into this, but getting funding for this research proved difficult. However, talking to colleagues he realised that different kind of fluid energy machines are used in many industries. “Fluid machines convert the energy stored by a fluid into mechanical energy or vice versa. You find them not only in rotary screw compressors but also in aircraft engines, ship propellers, and water turbines. They have one common denominator: their complex geometrical design”, he says. “That is how the idea for a joint European project arose, combining those four applications. We applied for funding under the H2020 Factories of the Future call.” Factories of the Future is the European Union's €1.15 billion public-private partnership (PPP) for advanced manufacturing research and innovation that aims to realise so-called Factories 4.0.

A consortium with big names helps

Möller and his colleagues brought together a strong consortium, including the Van Karman Institute for Fluid Dynamics (VKI), the Maritime Research Institute Netherlands (MARIN), MTU Aero Engines AG and Caterpillar. “We also had Professor Bert Jüttler from Johannes Kepler University Linz in Austria on board, one of the experts in Europe in geometry modelling,” says Möller. He believes the success of the proposal was due to the multiple applications of the technology. “One of our advantages was that in addition to the three science work packages – geometry modelling, simulation and optimisation – we also had four industrial applications. In the end, we generated several new technologies that are now being used in practice”, he says.

That was all according to plan: “We never wanted a single use-case project; we aimed for the synergy effects between the disciplines. For example, the level of automation between sectors varies: the aircraft industry is really at the forefront, whereas the maritime industry is rather conservative. Now, they were exchanging ideas. That was an important benefit of the project.”

Many steps are now automatized

Ultimately, the goal was to create tools for optimal design. “Before MOTOR, you would have to design a geometry, then simulate it, evaluate the outcomes and then optimise it step by step. Most of these steps were manual, with people spending weeks to create that initial geometry”, Möller explains. “Many of these steps have now been automatized. A computer generates the geometry and decides which parameters to tune based on the simulation of the flow fields.” The mathematical tools for geometric design and numerical simulation that came out of the project have been collected in an open software package, G+Smo. The name, pronounced ‘gismo’, is short for Geometry + Simulation Modules. G+Smo is already being widely used for science projects, but also by the industrial partners. “Some implemented the software into their workflow, others took the ideas and implemented them into their own software packages accordingly.”

H2020 is for pushing forward industry

The new geometry modelling techniques allow for greater model sophistication with less computational power. This has already led to positive outcomes. “Based on the simulation, you can now easily change the shape of your design, simulate it again, an reiterate until you are satisfied with the result. In the aircraft engine use case, this resulted in a considerable performance increase.” Another highlight of the project was the design of a dual-lead screw compressor rotor that is more efficient in high pressure applications. “It is the first of its kind in the world, but it is not just a scientific curiosity. TU Dortmund University developed it in collaboration with GHH RAND, who is considering to incorporate it in their commercial screw machine”, says Möller. “Ultimately, Horizon 2020 is not meant for writing scientific papers, but for pushing forward industry.”

Seeing it as an adventure

Möller hadn’t expected to become coordinator, but he didn’t shy away from the job either. “It evolved naturally. The project arose from the initial idea of two universities, and I had been closely involved from the start”, he says. “I had not done something like that before, so I saw it as a chance and an adventure.” He has learned a lot along the way. “Something I found out is that strict planning is important. You have to learn not to under- or overestimate the amount of work involved, as the budget of person-months and rates are fixed in the funding agreement”, he explains. “Some things are difficult to estimate beforehand. We created a completely new mesh generator for screw machine designs, for example, and it was difficult to gauge how much time that would cost.”

Recognition as a reward

Then there was the communications facet. “You have to talk to peers or experts, but also know how to make the project sound interesting to a wide audience and learn to speak about it in layman’s terms. That is something that doesn’t normally come to the job of a mathematician,” he explains. But even among project partners, communication could be a challenge. “Engineers and mathematicians already speak different languages, but talking to engineers from completely different disciplines adds another dimension.” There were rewards too: “You get recognition within the department and the university, but also beyond that. Very often people now ask me to come and talk about the project, or attend workshops to discuss my research. And the network that I built up during MOTOR is now the base for new projects.”

The importance of group dynamics

Retaining a good atmosphere within the group is another important aspect. “I had to learn how to keep everyone on board until we had fulfilled all requirements. The first critical point is when the proposal is awarded, you risk that people then start thinking that the work is done. The same goes for the intermediate review when the idea takes hold that nothing can go wrong anymore”, Möller says. “I could really practice how to motivate groups or individuals during these three years. I am now applying that on a much smaller scale to keep my students motivated. A bachelor programme is also a kind of project with a lot of enthusiasm at the start. Then, the first failure or disappointment hits. Or students are close to the finish line and don’t want to invest the time to improve their grade. Why don’t you try for a ten, and get a 8,5 instead of going for a seven from the outset?”

Keeping the ship afloat

Most of his time as coordinator was spend ‘keeping the ship afloat’: “I had to organise consortium meetings every six months and liaise with the European Commission. Every deviation or delay would not be communicated directly to the project officer, but to me”, he says. Helicopter view is something you definitely need. “You can’t be an expert on all the science involved, but you should have an overview. Sometimes, similar things were being done in different use cases, so I could avoid people re-inventing the wheel.” He praises the help he got from the Valorisation Centre. “They helped me organise and prepare for the review meetings a lot. They also assisted with all the paperwork, because as coordinator I had to compile and unify all the material that was written by the partners. With their help, I could focus mainly on managing the science, and the Valorisation Centre took care of the administration.”

Science is not just any other job

Möller would definitely advise others to take on the role of coordinator. “I learned a lot and broadened my network, and my visibility and that of my group improved. Also, research doesn’t always lead to anything concrete. I felt it was my responsibility to make sure that findings would also be used outside of the project.” At times it can be a fulltime job, though. “When you are preparing reports for a review, you should preferably be able to free yourself up for a whole month. Luckily, I was able to schedule lectures around such critical periods. But maybe if you have coordinated more projects, these things come more naturally.” There is one thing he councils against, however. “I would never manage a project outside of my own research. If you go for it, it has to be your own project. Then, you will live for it, and do not care about the extra hours. After all, science is not just any other job.”

'When you are preparing reports for
a review, you should preferably be able to free
yourself up for a whole month. Luckily, I was able to
schedule lectures around such critical periods'
'You can’t be an expert
on all the science involved,
but you should have an overview. Sometimes, similar things were being done in different use cases,
so I could avoid people
re-inventing the wheel'

Matthias Möller

Video shows the prototype of a dual-lead rotor that has been designed by TU Dortmund University,’s Chair of Fluidics, manufactured in Germany and investigated experimentally at GHH Rand. It is the first of its kind which makes it a very exciting project outcome.

An example of an air passage volume highlighted in blue. The novel geometry modelling techniques that have been developed in the MOTOR project have been applied to model the air passage volume with much more accuracy and flexibility in shape than this was possible before the project.