GO FASTER
Propelling a greener future
How CFD is driving the development of the most efficient propulsion systems.
By Luke Morris
Oceans cover more than 70% of the Earth.
So, it’s not surprising that 80% of global trade goods are transported by sea.
Add passenger ships to those large carriers and tankers and you have approximately 100,000 vessels in the entire world.
We typically think of cars and planes in relation to pollution, but these ships can also be incredibly damaging to the environment. The marine industry is estimated to contribute 2-3% of global greenhouse gas emissions, 5% of nitrogen oxides (NOx) and 4-9% of sulfur oxides (SOx). (Source: Statista)
As a result, the maritime industry is urgently prioritizing the enhancement of sustainability practices to prepare for impending stringent regulations. According to the International Maritime Organization, optimizing the propulsion system can improve a ship’s efficiency by as much as 10%. This would lead to a significant reduction in harmful emissions.
Saving the oceans with simulation
“If you want to save the planet, save the oceans,” says Saeed Javdani, Innovation and Technology Manager at Teignbridge Propellers International, which has almost 50 years of experience in designing propellers and shaftlines.
But this isn’t straightforward, as ships can harm the environment in different ways. First, the type and amount of fuel used contributes to carbon emissions. Second, noise pollution can do serious damage to marine life and biology.
To become a world-leading and reliable supplier of high-performance propulsion systems, Teignbridge uses both Simcenter™ STAR-CCM+™ software and HEEDS™ software to optimize propeller designs and make them as efficient and environmentally friendly as possible.
Working with Siemens Digital Industries Software solution partner, Maya HTT, Teignbridge has carried out fast and accurate CFD simulations in Simcenter STAR-CCM+ that allow design engineers to understand the interaction between propulsion systems and the high-velocity water flowing across their surfaces. They can predict performance, durability, and generated noise, then modify designs to optimize each aspect.
And all this can be done with simulation before any physical components even get wet.
“In the past we used to just consider one or two design points,” explains Javdani. “But now with Simcenter STAR-CCM+ we can predict how the vessel will perform at different speeds and in different sea conditions. Simulation makes it possible to explore many more iterations in less time so that we can then come up with the optimal design.”
Small changes deliver big results
Tiny alterations in propulsion system design can make huge differences. Even in an 8-meter propeller, a design adaptation of just 1 millimeter can have a noticeable performance impact. So, simulation is key to analyzing design changes and predicting the effect they will have.
In one instance, Javdani’s team identified cavitation – a phenomenon where vapor bubbles in a fluid grow and collapse due to local pressure fluctuations – as being caused by areas of low pressure on the leading edge of a rudder. By redesigning the rudder and aligning its leading edge to the downstream rotational flow from the propeller, the cavitation and noise were significantly reduced. And the vessel’s top speed was increased by approximately 7%.
In another situation, a customer needed to reduce radiated noise levels by 10 decibels to minimize environmental impact. By exploring hundreds of potential design iterations, Teignbridge was able to achieve a 15-decibel reduction.
The secret to this is the automation capabilities of HEEDS. “We can test up to 500 iterations in just 48 hours,” says Javdani. “Without HEEDS it’s simply not possible. It would take far too long and wouldn’t be cost-effective.”
Closer collaboration
Simulation has also been vital to satisfying classification societies and providing extra reassurance to customers.
“Simcenter STAR-CCM+ enables us to show authorities that new designs will meet their standards before they are even built,” says Javdani. “We can show that new components will perform within the safety factor required under dynamic loading.”
Group Managing Director, Mark Phare, explains that simulation has been essential to Teignbridge’s progress. “Naval architects expect propulsion designers to have CFD capabilities and to offer an analysis of the underwater equipment at the design stage. Many of our customers use Simcenter STAR-CCM+ which means we can easily share data and talk the same language when evaluating new projects.”
Becoming the best
Phare’s vision for the future of Teignbridge is straightforward but challenging: “We want to be the world-leading designer and manufacturer of propulsion equipment.”
And there’s no doubt that simulation will play a key role in making that a reality.
“Simcenter STAR-CCM+ has enriched the scope of work and sparked a great deal of innovation at Teignbridge,” says Javdani. “It helps us to better understand exactly what customers need, and helps us solve problems they didn’t even know they had. We can now design and supply products that we weren’t able to previously, opening up new markets and establishing ourselves as the go-to company within the industry.”