Mathematical Model Speeds Up Fuel-Efficient Engine Design
Designers can now test engines without having to build them.
On your marks ... get set ... go do the math! A mathematical model that lets engineers test-drive their design ideas could speed up the development of fuel-efficient systems for everything from minivans to rockets.
The computer model, which was developed by researchers at the University of Alabama, Huntsville, allows engineers to work through the numbers associated with a fuel system without having to actually design and build that system.
Chien-Pin Chen, chair of UA Huntsville’s chemical engineering department, and his team of researchers first had to create a surrogate fuel — a simplified fuel that they could represent mathematically.
The surrogate fuel has only three components, compared with the hundreds of components found in fuels such as gasoline. And while the surrogate fuel can be made in a lab, the researchers represented its characteristics purely mathematically. Now that they have the model, however, researchers can accurately depict all real-world fuels, from rocket fuelto common gasoline to the newer E85 ethanol-gasoline blends.
Once they established the fuel's mathematical model, Chen and his team were able to measure its use in different scenarios.
In modern automobile engines, injectors spray fuel into a combustion chamber at precisely timed intervals. The size, composition, behavior, temperature and pressure of the fuel droplets can all be measured and represented by the mathematical model.
Researchers used the model to demonstrate how fuel droplets from different injector designs will behave inside the combustion chamber, including how quickly they evaporate and how efficiently they combust.
“We are already changing the injector designs,” said Chen.
The mathematical model is also changing the way that engineers approach new fuel systems. Chen said that it has led to more research in areas like fuel turbulence, which, if reduced, could help cars and trucks run more smoothly and lengthen an engine’s lifespan.
“The long-term goal is to find a way to burn fuel more efficiently for more power and cleaner combustion,” Chen said.
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