Driving sustainability through Virtual Twin Technology, while enhancing Aerodynamic Performance with Advanced Fluid Simulation.
Volvo primarily manufactures heavy-duty trucks, buses, construction equipment, and diesel engines as well as marine applications, and like many OEMs, is beginning to produce electric vehicles also.
In today’s connected, global economy with its streamlined supply chain, goods are transported all over the world. As they make their way to a store near us or, increasingly, to our doorsteps, they were invariably transported there by trucks, at least for some part of that journey.
In an age of online shopping—especially in the wake of the recent COVID-19 lockdowns—trucking is critical to our daily lives. However, the transportation of goods and people today is mostly powered by fossil fuels, which emit greenhouse gases (GHG) when burned. In the US, the transportation sector accounted for 28% of the overall GHG emissions in 2018—and 23% of that sector emission came from medium and heavy-duty trucks [1]. This makes the trucking industry a major player in the effort to minimize tailpipe emissions of GHG. At Volvo Trucks, care for the environment is one of our core values.
The Project
Volvo Trucks believe in sustainable transport solutions. Although electric trucks are here, they know that their widespread adoption may take some time. Therefore, in addition to Volvo’s investment in electric and hydrogen-powered trucks, they are also focused on reducing the tailpipe GHG emissions of their diesel-powered trucks, to carry society through this transition period.
Raja Sengupta is responsible for the aerodynamic certification (for CO2) of Volvo’s North American product portfolio and is in charge of aerodynamic development for the SuperTruck II project sponsored by the Department of Energy. The SuperTruck project began in 2011 with a challenge to improve freight efficiency by 50%. SuperTruck II doubled that target to 100%. Sengupta worked on the original SuperTruck, as well as the ongoing SuperTruck II project, and describes the program as the greatest opportunity of his career.
Raja’s team had three key focus areas in this project:
- Reducing the weight of the tractor and the trailer
- Improving the efficiency of the powertrain
- Drastically reducing the aerodynamic drag
CFD Simulation and Digital Twin Technology Drive Innovation
To improve the aerodynamic design of their baseline required extensive experimentation. Fortunately, Volvo Trucks is an advanced user of virtual experience twin technology (also known as “digital twin” technology). This powerful combination of virtual 3D design and multi-physics CFD (Computational Fluid Dynamics) simulation allowed Raja and his team to experiment in the “Digital Wind Tunnel” with real-life accuracy, testing thousands of variations in a fraction of the time and cost that would be required for testing with physical prototypes.
Unlike physical testing, our virtual experience twin process offers detailed visual insight into the airflow around the vehicle. This is critical as it drives our iterative design process— every design change is based on learnings from the previous iteration, thereby continuously improving the aerodynamics until we reach saturation or diminishing returns.
After hundreds of tweaks and dozens of iterations, we were able to reduce the overall aerodynamic drag of ST1 by 40%, yielding a 20% direct improvement in fuel economy. But there were indirect benefits as well.
At a cruise speed of 65mph, almost half of the road load on a tractor-trailer comes from air resistance or aerodynamic drag. Therefore, by drastically reducing the drag, we were able to downsize our engine—from a 13L 485HP in the baseline to an 11L 425HP in ST1. This reduced the weight of the tractor (thereby increasing payload and therefore, freight efficiency) and lowered the engine cooling demand from what was originally anticipated, which meant we could use a smaller cooling package. This resulted in a narrower hood, a smaller grille opening, and a much lower cooling drag.
Project Update: Paving the road to success
On the heels of the success of ST1, the DOE initiated the Supertruck II (ST2) program in 2016 and doubled the challenge—to achieve 100% improvement over the same 2009 baseline.
The project is still ongoing as we enter the final, build phase. However, the tractor-trailer design was frozen a while back, a culmination of a similar process as ST1 powered by the same virtual experience twin technology. This time, the team were able to reduce the overall drag by 50% over our 2009 baseline—almost 20% over ST1. MY2009 Baseline Volvo Supertruck 2.
Supertruck is similar to a concept car; while many of the improvements already are, or soon will be, incorporated into our commercial offerings, others need more work to bring down their cost. And Supertruck II isn’t the end of the journey: they recently announced Supertruck III program will focus on battery-electric and fuel-cell-powered vehicles—the designs that will move the trucking industry from a transitional period of lower tailpipe GHG emissions to one with zero tailpipe emissions.
Discover PowerFLOW
COMPUTATIONAL FLUID DYNAMICS SIMULATION SOFTWARE IMPROVING PRODUCT DESIGN & DEVELOPMENT
Using the PowerFLOW suite, engineers evaluate product performance early in the design process prior to any prototype being built — when the impact of change is most significant for design and budgets. PowerFLOW imports fully complex model geometry and accurately and efficiently performs aerodynamic, aeroacoustic and thermal management simulations.
Key Capabilities:
- Fast automated setup: Create and import geometry, define initial & boundary conditions and choose measurements to record during simulation with this application. The intuitive, fast interface application provides an entirely automated fluid grid generation solution.
- True rotating geometry: PowerFLOW can simulate true roating geometry to optimize performance and noise in systems, such as wheel aerodynamics, brakes, HVAC systems, cooling fans and more.
- Coupled simulations: PowerFLOW suite has the ability to seamlessly integrate PowerTHERM surface termperature & heat fluxes technologies and PowerACOUSTICS aeroacoustic noise technologies to existing simulated designs.
- Digital wind tunnel: The digital wind tunnel model includes static and moving ground plane modeling and boundary layer suction points to match that of real-life experimental wind tunnels.
- Analyze designs: Upon simulation completion, PowerVIZ analyses results quickly and PowerINSIGHT automates results analysis.
- Rapid turnaround time: Once a surface mesh model is prepared, the same model may be used to perform additional simulations. Setup, grid generation, simulation and results analysis can be performed in less than a day.
Sources:
Originally published: https://www.3ds.com/fileadmin/PRODUCTS/SIMULIA/IMG/products/PowerFLOW/Volvo-case_studyUPDATED.pdf
[1] “Fast Facts on Transportation Greenhouse Gas Emissions.” EPA, Environmental Protection Agency, 8 June 2021, www. epa.gov/greenvehicles/fast-facts-transportation-greenhousegas-emissions.
[2] Lobner, Peter. “SuperTrucks—Revolutionizing the Heavy Tractor-Trailer Freight Industry with Science.” The Lyncean Group of San Diego, 3 Apr. 2020, https://lynceans.org/tag/ doe-supertruck/.
[3] Delgado, Oscar and Nic Lutsey. “THE U.S. SUPERTRUCK PROGRAM” https://theicct.org/sites/default/files/ publications/ICCT_SuperTruck-program_20140610.pdf.
