My PhD

My research aims to make machines run as smoothly as if they were lubricated with oil

Janus Jedig-Walentin Jensen’s PhD project aims to improve air bearings, make them more widely used, and eventually replace oil bearings.

Janus working on the air bearing.
Jedig-Walentin Jensen’s PhD project can make machines greener and simpler, reduce oil consumption, and thereby lower production costs. Photo: Sine Fiig

Thursday 09 April 2026

Christian Tremmer

My PhD project is about …

… making air bearings more widely usable in industry. A bearing is a machine component that supports the weight of moving parts and separates contact surfaces with a lubricating film. This allows the moving parts to rotate or slide without friction, which can otherwise cause wear, reduced efficiency, and harmful vibrations in the machine.

Air bearings are simple because they require only air instead of oil, equipment such as pumps, and oil tanks. Instead of oil, a thin air film forms between the bearing and the moving machine part, preventing them from touching and damaging the machine.

Today, air bearings are most commonly used in fast and lightweight machines, such as in aircraft air circulation systems. This is because air—unlike oil—is less viscous and easier to compress. Therefore, air bearings require the parts to rotate at high speeds to generate sufficient pressure to support the weight of the rotating parts. This limits current air bearings to fast and lightweight machines.

To solve the problem, we’ve created holes in the center of the bearing through which we blow high-pressure air. This increases the bearing’s ability to support weight without rotating itself—much like when a puck hovers on an air hockey table.

By measuring the moving parts relative to the bearing, we can create an algorithm that automatically adjusts the airflow, resulting in improved bearing performance. This way, we avoid harmful vibrations and enable air bearings to support more weight, making them suitable for use in far more industrial machines.

Facts

About the research

  • Name: Janus Jedig-Walentin Jensen
  • Age: 26

  • Education: MSc in Mechanical Engineering (Design and Mechanics), Technical University of Denmark

  • Project research field: Rotordynamics

  • Project period: 2024-2027

  • Supervisors: Professor Ilmar Ferreira Santos, DTU Construct, Professor Jens Honore Walther, DTU Construct, R&D Engineer Alejandro Javier Varela, GEA Process Engineering A/S

The research can contribute to …

… replacing some of the systems that currently use oil bearings with air bearings. This will both reduce the need for oil in the future and make it possible to develop machines that otherwise could not function with oil bearings.

Oil bearings are often used in the production of medicines or food. To avoid oil particles in the products, the machines are made more complex. With air bearings, the machines can become much simpler—or even make it possible to produce in new and efficient ways.

I get new ideas for solutions …

… when I talk to researchers from other fields. Even though our problems aren’t the same, I can sometimes use their methods—which work in many different areas—to find solutions to my own challenges. I also get ideas when I’m biking, because that’s when my mind is free to wander.

It’s been a good day at work when …

… there’s a problem, and I find a solution to it. For example, I recently built a regulator for the bearing, installed it in the machine, and saw that it worked really well. It made me happy to have built something that works and can be used in practice.

I take a break from work when…

… I bike to and from work. It’s a good half-hour ride, so it’s a really nice trip. Besides that, I have two wonderful kids whom I love to play with. It’s wonderful just to be able to spend time with them.

I became a PhD student at DTU because…

… I wasn’t done learning new things. I was and still am incredibly curious. There was an opportunity to pursue a PhD in a subject I’d written my master’s thesis on, and it was very broad. It involves creating models, designing control systems, and testing them experimentally—and those are exactly the things I find exciting.

As a new PhD student, I was surprised by …

… how friendly the professors and the research community can be. I’ve attended a few conferences where I’ve had the opportunity to meet some incredibly talented people in various research fields.

The biggest challenge I face as a PhD student is…

… setting up a test rig that’s good enough to demonstrate the desired effects when the budget imposes limitations. Part of my PhD involves proving that the models and control systems we build actually work in the real world. There’s a lot of technical work involved in assembling, designing, and redesigning, which often takes longer than you think, but is very satisfying when it succeeds.

In the future, I’d like to work with…

… research and product development. It’s fun to do research in a field that’s also really broad. There are many factors you need to understand and take into account before you can correctly explain or model how a bearing works. As I said, I’m still curious, but I’d also like to try my hand at industry and apply the tools I’ve gained as a PhD student to new problems—both with and without bearings.

Contact

Janus Jedig-Walentin Jensen

Janus Jedig-Walentin Jensen PhD Student Department of Civil and Mechanical Engineering