Fuel simulation for the real world

Posted on 27. Sep, 2013 by in Academic Departments, Annual Report, Environment and Sustainability, Issues, Mechanical Engineering, Research

fuel simulationMechanical Engineering Assistant Professor Mario Trujillo confidently predicts that liquid fuels are not going away, but understanding how they’ll behave in fuel-injection systems will become increasingly complex. “There is probably going to be a wide range of new fuels with different physical properties, which means liquid fuel injection is going to change,” he says. “There’s a need to have more predictive science.”

With funding from Caterpillar Inc., Trujillo is developing simulations to predict how different fuels will disperse on their way to an engine’s combustion chamber. His research group’s work complements that of several colleagues in the Engine Research Center, whose interests include emissions, engine performance, and turbulence models. Having better access to predictive simulations potentially could impact every aspect of how Caterpillar develops new diesel engines.

“The diesel spray is one of those areas where the physics are not modeled as well as they need to be,” says Chris Gehrke, a senior engineering team lead at Caterpillar. “It impacts everything in the simulation from emissions to the thermal stresses on the mechanical components of a cylinder.”

But the sorts of incredibly vivid, physics-driven simulations Trujillo has been creating in recent years involve vast expense, time and computing power. It’s impractical for a company to run many such simulations in the course of developing a new diesel engine. “The recurring message from industry is: ‘Look, our computations have to be done quickly,’” Trujillo says.

The Engine Research Center solution is to stake out a middle ground and break the simulation down into two parts: Use the intensive computer-simulation approach in the near field (where the fuel is closer to the nozzle), and a more traditional modeling approach further along in the flow.

Ultimately, access to predictive simulations will spare Caterpillar a great deal of real-world testing when it’s developing diesel engines. “If we can make our simulations more predictive, they’ll become more useful,” Gehrke says “It will impact on our engine development process across the entire diesel engine product line.”

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