To know what happens inside a cylinder of an outboard engine regulating during 5500 rpm, BRP/Evinrude got some assistance from an doubtful source: program formula creatively created to know a suit of atmosphere after an atomic explosve explosion.
The production of liquid upsurge are germane in both cases, says Rolf Reitz, a highbrow emeritus of automatic engineering during a University of Wisconsin—Madison. In a 1970s, in response to a OPEC oil crisis, Reitz helped repurpose formula created by a weapons organisation during Los Alamos National Laboratory for a automobile industry.
The outcome became a basement for a package called KIVA that predicts and explains a rarely formidable events inside an engine’s cylinder, permitting designers to strech a “sweet spot” of high power, good fuel economy and low emissions.
The cylinder is a formidable place, says Paul Westhoff, a automatic operative during BRP/Evinrude in Sturtevant, Wisconsin. Westhoff led a computational liquid energetic displaying during a “blank piece of paper” pattern for a blast cylinders in Evinrude’s E-TEC G2 engines, introduced in 2014.
“Everything is relocating quick in a really interactive system,” he says.
To take usually a few vicious variables, designers contingency change a location, distance and figure of a intake and empty ports; a figure of a piston and cylinder head; and a timing and instruction of a fuel mist and a hint that ignites a explosion.
These factors sum impact how atmosphere enters a cylinder and mixes with a fuel spray, and how a burnt gas exhausts after a explosion. Reaching one idea can concede another, Westhoff explains. “You wish to brew fuel and atmosphere via a cylinder, though don’t wish fuel going out a empty port.”
Evinrude’s new engines, that operation from 200 to 300 horsepower, are two-stroke, direct-injected engines, and paint a industry’s best multiple of power, economy and low emissions, Westhoff says.
Because a fanciful brew of designs is radically uncountable, a normal routine of engine pattern — reliant as it is on steel prototypes — is expensive, and each alteration costs some-more money. Yet until recently, engine designers had few alternatives.
So when BRP/Evinrude, a princely Wisconsin manufacturer with 700 employees that is now a multiplication of BRP Inc., embarked on a sum redesign of a flagship high-power outboards, it took an wholly opposite approach: conceptualizing in silico.
The routine relied on KIVA, open-source program that has been underneath solid growth during a UW–Madison Engine Research Center.
Reitz began operative on program to report furiously relocating fluids for his Ph.D. work during Princeton University in a late 1970s. “The Department of Energy wanted to take a ruling equations from Los Alamos investigate — a production should be a same — and request them to engines, and they were really successful,” Reitz says.
Eventually, a program beliefs and imagination grown during UW–Madison widespread by a automobile industry, and KIVA and associated program from private companies has been put to work by Ford, Cummins, Caterpillar and many other large engine makers, Reitz says.
In his prolonged career exploring a formidable events inside engines, Reitz has also used KIVA to rise gasoline-diesel hybrid engines that offer some of a top potency in a world.
Westhoff says Evinrude’s “blank piece of paper” pattern routine began where all a movement starts: inside a cylinder. “We modeled liquid upsurge by a cylinder — a initiation of atmosphere from a crankcase by a intake pier into a cylinder, that displaces a residual empty from a prior cycle. It’s critical to maximize a volume of trapped oxygen, since a some-more oxygen in a cylinder, a some-more power.”
The E-TEC G2 engines are Evinrude’s second era two-cycles regulating fuel injection, though a initial to be designed in silico. “Previous generations of approach injection engines were essentially adaptations of a fuel complement from an existent carbureted engine,” Westhoff says. “With approach injection, we have a ability to conduct a fuel upsurge that we don’t have with a carburetor. This is new technology.”
Do-overs are roughly giveaway with mechanism design, he adds. “Using mechanism modeling, we can do hundreds of runs and try potentially high-benefit, high-risk paths. If we had to antecedent them, we would run out of money.”
But that’s usually loyal if a indication is “smart enough” to obey a genuine universe of air, fuel and relocating metal. And here, Reitz says, KIVA has benefited from a corridor full of exam engines during the Engine Research Center that are used to endorse and urge a fluid-dynamics software.
The KIVA program doesn’t usually weigh designs; it also explains because they act as they do, Westhoff adds. “An engine can be a black box, though this helps us know a physics. If we demeanour during a three-dimensional displaying results, they can make we consider differently, and that leads to other ideas. The outcome is not your grandpa’s two-stroke.”
Source: University of Wisconsin-Madison