People power

A conversation with Veli-Pekka Peljo, who led the multidisciplinary team that created ABB Dynafin™.

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_{Fatima Choaïbi ABB Marine & Ports Helsinki, Finland fatima.choaibi@fi.abb.com
Roderick Craig External contributor}

Veli-Pekka Peljo, Senior Project Manager, Solutions Development →01, joined ABB Marine & Ports in 2003 as a design engineer and immediately rolled up his sleeves on the continued development of ABB’s Azipod® propulsion technology. Ten years later, he was called on to helm the multidisciplinary team that gave birth to ABB Dynafin, launched in May 2023. Here, he explains how the concept came into being, the collaborative effort needed to bring it to the prototype stage and why a clear goal and open mindset are key to handling uncertainty.

It has been a long journey since 2013, when Peljo took charge of ABB’s Total New Propulsion project to develop a propulsion unit with an efficiency of over 80 percent. “Already then, electrification of vessels was seen as a trend, but the green transition was still to come. At that time, marine fuel prices were at an all-time high, so fuel efficiency and reducing emissions were at the front of people’s minds and became the main drivers for the project.” 

Right back to basics

When they started out, Peljo and his team understood that it was not possible to dramatically improve the efficiency of conventional screw-propeller-based solutions beyond the incremental improvements already achieved. “To address the challenge, we knew we’d have to go right back to basics – drill down into the theoretical underpinnings of how to create thrust and come up with something radical from scratch.”

ABB first enlisted the help of engineering students at Aalto University in Espoo to do a big-picture analysis of the ideal propulsor in what they call a Product Development Project (PDP) [1]. They studied the literature to identify what concepts had been floated in the past and what patents were available. “That generated a lot of ideas – everything from screw propellers, paddle wheels and air propulsion to electromagnetic thrusters and biomimetic propulsion – the Aalto guys analyzed how fish, different sea mammals and even insects create thrust,” Peljo says.

The combined Aalto/ABB team ended up with 69 concepts, all of which were tested against ideal propulsion theory. Two major criteria for the best solutions were optimal utilization of the transverse area at the back of a vessel and enabling the greatest efficiency at the lowest cost. “That involved a lot of workshops where we finally identified five concepts to take forward: Azipod® XL, a rim-driven nozzle propeller, an advanced paddle wheel concept, a flapping hydrofoil and a trochoidal propeller,” explains Peljo.

“After further iterations, we saw that using a flapping foil or blade that mimics the movement of a whale’s tail (known as a trochoidal trajectory) was undoubtedly the most efficient solution. That was the germ of the idea that became the ABB Dynafin.”

Solving the puzzle

The challenge was how to connect the flapping foil to the rotational movement of an electric or diesel motor shaft to propel a vessel. “You could have a single foil moving up and down, but we figured the best way would be to use multiple vertical blades connected to one central rotating wheel. We then contacted VTT – a state-owned technical research center in Finland and one of the top institutes in Europe – to collaborate with us in creating hydroanalytical models to see exactly how this set-up would generate thrust [2].

“The solution was to give each blade its own driving motor, allowing for independent control so you can pre-program the angle of attack of each blade against the inflow as the main wheel rotates, taking into account the vessel’s wake field.”

“VTT were very fast to prove the concept, with their calculations indicating an efficiency of over 0.8 with an optimized trochoidal trajectory of the blades. We also used their formulas to optimize geometry factors, including the span and chord dimensions of the blades, and operational parameters such as RPM.”

CFD proves the concept

The next step was to create an initial design for computational fluid dynamics (CFD) analysis, which – as the combined project team expected – validated VTT’s formulas and showed that the solution works. “Doing CFD, especially 3-D CFD, is time-consuming as a single model can take up to a day to process. You need to have come quite a long way before you do it. We were then able to extract the load data for detailed dimensioning of the supportive structure – for example, the center wheel, blade motors and bearings,” says Peljo.

It was only after doing the CFD that the team started to really think about how they could make the concept work in real life. Having little experience in control software solutions, Peljo and his colleagues Mirva Nevalainen, Product Manager, and Jukka Varis, Technology Manager, pitched the concept to Bin Liu, Senior Principal Scientist and his team at the ABB Corporate Research Center (CRC) in Västerås, Sweden and asked if they could make a model-scale prototype. “Pre-programming the movement and angle of attack of the blades was one of the biggest challenges, but being world leaders in robotics – they are the experts behind ABB’s family of YuMi® collaborative robots – this was well within their capability.”

Starting in 2016, the ABB teams collaborated on a novel cycloidal propulsion technology project, resulting in a prototype and the first novel small-scale demonstrator vessel, which was built and operated on Lake Mälaren, just outside of Västerås.

Defining moment

The resulting prototype was hydrodynamically tested in the VTT model basin in Espoo, Finland and then self-propulsion and maneuvering capabilities were confirmed in open-water lake trials in Sweden. It worked as predicted. “We did everything you’d do in a full-scale sea trial program. That was a fantastic milestone and confirmed all our hard work. We knew then we could really make the concept, which we originally called ‘Foilwheel,’ fly as a world-first digital propeller with extraordinary efficiency,” comments Peljo.

To those who might wonder why nobody had done this sooner, Peljo’s answer is: it’s not that simple. “ABB Dynafin may look similar to some mechanical solutions, but inside it’s totally different – the main thing being the blade motors and entire drive train. 

Instead of mechanical levers controlled by hydraulic servo actuators, we have electric motors with low RPM and high torque that we can match with the propeller blades at full scale.”

He says the final ABB Dynafin units will be of standard design, although of different propeller diameter sizes depending on the power factor. This shortens delivery lead time. “Then you just select the right blade length to fit the vessel draft. It could be that we offer only two different blade lengths, but our target is to keep the blades above the baseline.”

The fatigue strength of the blades is a critical design issue, so they need very careful design to ensure the required service life with high reliability. “We’re currently thinking martensitic casted stainless steel but given certain manufacturing constraints, we may need to use composites for the longer blades on higher-power units. We’re also working on details like sealing solutions to achieve an optimal total cost of ownership.”

Target markets

In terms of which vessels the concept is most suited to, Peljo explains that right now they are “just scratching the surface.” He elaborates, “we are aligning it with customer requirements for different segments, but there are a lot of possibilities. Transit vessels will see the biggest benefit and the faster the speed, the bigger the benefit. But we’re mostly looking at 12 to 20 knots at this stage. With ABB Dynafin, you get many different design points in just one propeller: one for maximum sea-trial speed, one optimized for economy speed, one for safe return to port at six knots, one for dynamic positioning operation and so on. It’s very versatile and can suit all sorts of ship types.”

In terms of power factors, ABB is working towards four sizes, from 1 MW to 4 MW. Four 4 MW units on a vessel would give propulsion power of 16 MW. “There’s interest in the market to go even higher, so we’re also looking at 5 MW units and upwards,” adds Peljo.

Thanks to its integrated controllable pitch propeller (CPP) feature, ABB Dynafin has the dynamic positioning capability necessary for offshore vessels. “It can change thrust direction through 180 degrees in seconds, providing a very fast response time if you need to change vessel heading. With multiple units, we’re also looking at how ABB Ability™ Marine Pilot Control can best utilize ABB Dynafin unit’s capabilities for all operational modes and autopilot configurations, with a view to remote operations and eventually autonomous operations.”

There are also low-vibration vessel cases. “The RPM is quite low at full power, but the amplitude is higher. The pressure pulses from a vertical propeller don’t interfere too much with the hull, but we can tweak the blade trajectories even more to eliminate vibration and noise almost completely for silent operations.”

Moreover, ABB Dynafin boasts other valuable features, such as regenerating power when braking the vessel, just like a self-charging hybrid car. “You can charge onboard batteries simply by the action of the water turning the blades like a windmill. 

Then we also have the so-called rudder mode, meaning that, when the propulsion drive is inactive, that is, with the main wheel stopped, all the blades can work together to steer, for example, a sail-assisted vessel →02.”

Dealing with uncertainty

Peljo highlights that there is always uncertainty when developing a new concept from scratch. “To handle that, the human factor has to be constant; it’s essential to maintain a creative, open mindset and a strong focus on the goal even if the requirements are vague. Innovation is not all about luck and in-the-moment inspiration; we had a lot of arduous concept rounds. Looking back, we could, of course, have moved faster, but we’ve had a lot of parallel projects to work on, too,” he adds.

Having a proven R&D methodology is also crucial. “We use the applied ship design spiral, where you move from mission requirements to high-level concept analysis on the outer circle and gradually work inwards, honing the design in greater detail. You can’t get bogged down in details too soon. Having a clear business case also stops you from getting distracted in theoretical niceties that waste time.”

Kudos for partners

Peljo stresses that there was “no way we could’ve done this alone.” ABB Dynafin has been the result of pulling together expertise in mathematics, hydrodynamics, mechanics, electrical and control, and we’ve had great partners in Aalto University, VTT and the ABB CRC. So, having the right mix of people, combined with ABB’s strong culture of innovation and determination to always do better, has been crucial for success.”

As to his personal motivation, Peljo trained as a mechanical engineer and loves R&D work because no one day is the same as another. “I’d be bored stiff doing the same thing day in, day out. The project was a once-in-a-lifetime opportunity and it’s fantastic to have come so far in bringing ABB Dynafin to reality.”

“Given the high cost of new green fuels and the increase in fully electric vessels, the business case is even more attractive,” Peljo adds. “Contributing to the green shift gives extra meaning and I believe it’s great timing for what is an exceptional novel technology. We are working hard on the details and I can’t wait to see the first ABB Dynafin live on a real ship.”

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