Using simulation to reduce testing duration of motorcycle aerodynamic optimization by 90 percent

Converting traditional enthusiasts to electric

Although the transition to electric cars is well underway, electric motorcycles have lagged behind. It’s unsurprising given these products attract two different types of customers. Most cars are focused on getting from A to B in comfort and safety, while motorcycles are more of a passion. Riders are looking for speed, feel and the overall experience of each journey.

Energica is aiming to accelerate the transition with its range of high-performance, fully electric motorcycles. “For petrol motorcycle enthusiasts, there’s a big emphasis on the noise and the smell,” says Giampiero Testoni, chief technology officer (CTO) of Energica. “But climate change is a real threat that nobody can ignore. We wanted to encourage the new breed of electric motorcycle enthusiasts by giving them the same level of performance but without pollution.”

Accelerating aerodynamic development

To develop a high-performance motorcycle requires not only an effective powertrain but also highly refined aerodynamics. When Energica started developing electric motorcycles, all the aerodynamic testing took place in wind tunnels. This provided an excellent appraisal of performance but was an expensive and time-consuming exercise.

Testoni explains the company needed to find an alternative solution to continue growing. “Time-to-market is vital,” he says. “We often must book wind tunnels a year in advance and hope that we have everything ready to test by that point. Cost is a factor too, but the most important thing was to speed up aerodynamic optimization so we could finish the final product sooner. The electric vehicle market progresses much faster than combustion vehicles – similar to the electronics consumer market – so if we can’t reduce our development time as much as possible, we’ll be left behind.”

To accelerate aerodynamic development, Energica turned to Siemens Digital Industries Software’s Simcenter™ FLOEFD™ software and Simcenter STAR-CCM+™ software. Simcenter is part of the Siemens Xcelerator business platform of software, hardware and services.

“The main reason for choosing Simcenter was that we knew from the start it had a full suite of interconnected tools,” says Testoni. “If you have different products for electronics, mechanics, NVH and 1D simulation pulling all the results together quickly becomes complex. The Simcenter portfolio makes this much more straight-forward, which was very attractive to us. Also, being able to start with one or two Simcenter tools and then gradually add others has been really helpful as our development processes have evolved.”

Optimizing comfort with Simcenter FLOEFD

Energica’s motorcycle models are designed with different users in mind. The Energica EsseEsse9+ is primarily focused on rider comfort, so understanding how air impacts the chest of the rider was key to aerodynamic optimization.

For this, Testoni used Simcenter FLOEFD to simulate the effect of air currents on a full model of the motorcycle, including all the individual components. “Simcenter FLOEFD is easy to use and has excellent integration with 3D CAD, enabling fast, accurate CFD analysis of models with complex geometry,” says Testoni. “We could immediately see how the air was impacting the rider and experiment with design modifications to minimize this.”

Although comfort was the priority of this model, performance was still important, so the team had to ensure these modifications did not significantly slow down the motorcycle. They added a front fairing, higher screen and handguards to lower the impact and speed of the air flux. This improved rider comfort but also created turbulence near the rider’s chest. To mitigate this, they made further modifications by lowering the sides of the screen and adding an air duct to the front fairing to reduce drag. Overall, the front area of the motorcycle was increased by 3.7 percent and simulations showed this would significantly improve rider comfort. Despite this, the front drag coefficient (Cx) only increased by 0.6 percent, meaning the motorcycle could still achieve the expected top speeds.

Using Simcenter STAR-CCM+ to optimize speed

The MotoE Ego Corsa racing bike is built to prioritize performance. To improve the top speed and efficiency it was important to understand exactly how the design influenced drag. For simulation to be effective, there had to be a direct correlation between its data and that coming from wind tunnel tests. So, Energica used Simcenter STAR-CCM+ for simulation to
recreate the wind tunnel and replicate real-world testing.

“Once we were confident that Simcenter STAR-CCM+ was accurately replicating the wind tunnel, we could test all our design modifications with simulation instead,” says Testoni. “This meant we didn’t have to wait months for wind tunnel time and test setup was much faster and easier. We were able to try out many more iterations in a shorter time, allowing us to reach a true high-performance aerodynamic design that maximized top speed and efficiency.”

Significantly reducing development time and costs

Using Simcenter FLOEFD and Simcenter STAR-CCM+ has enabled Energica to reduce development time and costs. “Now that we have the full simulation environment setup, we don’t need the wind tunnel during aerodynamic development anymore,” says Testoni. “We only use it for final validation of the full motorcycle. Using Simcenter FLOEFD and Simcenter
STAR-CCM+ has meant that our testing is completed 10 times faster and costs are approximately five times cheaper as we don’t have to build prototypes, book wind tunnels and spend days of engineering time setting up tests.”

Testoni appreciated the expertise provided by Siemens for the initial setup of Simcenter FLOEFD and Simcenter STAR-CCM+ and their ongoing support. “The training was first class,” he says. “Most importantly, we were taught by people who are engineers and have used these products in the real world. They’re not just explaining theories, they’ve done this themselves and come up against the same problems we face.

Beyond motorcycles

With the aim of incorporating more tools from Siemens Xcelerator, Energica recently renewed its partnership with Siemens for three years. “Simulation is now a fundamental part of Energica’s development process,” says Testoni. “We’re excited to continue working with Siemens to implement more tools that are part of Siemens Xcelerator, such as Simcenter Amesim and NX, to improve our products.”

This will also help Energica as it expands beyond motorcycles: “Adopting more tools from the Siemens Xcelerator portfolio will be crucial for our new business unit, Energica Inside,” says Testoni. “This is designed to bring our experience and technology to different markets such as batteries and powertrains for electric tractors, go-carts, small airplanes and boats. The more time and money we save by using simulation, the better products we will be able to get to market sooner to satisfy customer demand.”