Building better engines through natural selection

Could Charles Darwin’s rules of evolution help engineers design high-performance engines of the future? This is the focus of current computer modelling at the University of Wisconsin-Madison, where researchers are using genetic algorithms to simultaneously increase fuel efficiency and reduce pollution.

Peter Senecal, a post-doctorate engineer at UW-Madison, created the computer models to help sort through literally billions of combinations of factors that determine engine performance – a task too enormous for conventional computer simulations.

Senecal says the most important advance is in improving pollution emissions without sacrificing fuel efficiency, and vice versa. Normally, engine designers who concentrate on solving one problem end up with major tradeoffs in the other.

The results to date have been dramatic. Using a Silicon Graphics supercomputer at UW-Madison’s Engine Research Center, Senecal created a diesel engine design that reduces nitric oxide emissions by three-fold and soot emissions by 50 percent over the best available technology. At the same time, the model reduced fuel consumption by 15 percent.

Six engine performance measures were studied, including fuel injection timing, injection pressure, and amount of exhaust recirculation. The simulation was then reproduced experimentally in a real diesel engine housed at the ERC.

His work also is turning heads in the engine manufacturing industry, which faces major new federal pollution control mandates by the year 2002. Caterpillar Inc., a Peoria-based manufacturer of diesel engines for trucks and heavy equipment, is funding Senecal’s post-doctorate work that will focus on improving the geometry of engines.

Mechanical engineering Professor Rolf Reitz, Senecal’s Ph.D. thesis advisor, says the computer model is extremely versatile and could be used for all types of engines. While curent work focuses on questions like fuel injection and air intake, studies of engine hardware are just beginning.

Reitz says the typical engine piston, for example, has not been fundamentally improved upon for decades. Yet engineers have no idea whether a different geometry could produce much better engines.

If engine manufacturers want a more powerful engine, or a more durable engine, one can program the genetic model to find those traits, too. ‘If you want your children to be long jumpers, high jumpers or sprinters, you can specify these attributes with this program,’ Reitz says.

The diesel engine industry faces a U.S. Environmental Protection Agency mandate to cut nitric oxide emissions in half by 2002. Wisconsin’s small engine industry, also facing pollution-control deadlines, also has initiated a research program at UW-Madison using the genetic model.