When packs of drivers jockey for position on the speedway at Sunday's Indianapolis 500, a select group of engineers will be thinking, not about engines and tires, but about the effects of laminar and turbulent airflow.
"It's one thing when you're riding around the track and there's no air disturbance," Mark Johnson, general manager of KV Racing Technology, told us. "But when you're in a three- or four-car pack driving through disturbed air, it's another matter. That's why the wind tunnel simulation is so important."
Indy's engineers spend hundreds of hours testing cars in wind tunnels. Along with on-track testing, KV Racing employs a "rolling road" at a wind tunnel to build an "aero map" of its vehicles. The rolling road, operated by Wind Shear Inc., measures 10.5 feet wide and 29.5 feet long. Its continuously turning steel belt can accelerate from 0 to 180mph in less than a minute and incorporates a measurement system that monitors the aerodynamic downforce under each tire.
Indy cars can use aerodynamic downforce to ride lower and get a better grip on the road. (Source: Littelfuse)
"Going to the wind tunnel is critical to our understanding," Johnson said. "The engineers learn what happens when they make a change on the rear or front of the car, and they find out what they have to do in order to make all the changes work in concert with each another."
Given the new rules at Indy, those changes won't be big, but they can still make the difference between victory and defeat. One of the key components not constrained by the rules is the wicker -- a little piece of angle iron on the car's front and rear wings. The wicker, measuring anywhere from one-sixteenth to one-half of an inch in cross-section, can run the full width of a wing (about 18 inches across). By altering the size and angle of the wickers, engineers can significantly change the aerodynamics of their vehicles. To find out how much change they've wrought, they bring the vehicles to the wind tunnel or to the actual track and take measurements.
At a track in Texas, for example, KV recently experimented with wickers to provide more aerodynamic downforce for a rookie driver. Starting with a flat rear wing and varying the size of the wickers on the front up to three-eighths of an inch and then down to one-fourth of an inch, they found they could produce amazing amounts of downforce. "We got to where he could drive around the track and never lift the throttle for five or six laps at a top speed of 205 miles per hour," Johnson said. "After he got more comfortable, we took a little bit of the wicker off."
Such adjustments are commonplace for Indy race teams, Johnson said. Through trial and error, they learn how to use aerodynamics to make their cars ride high or low, increasing or decreasing drag and thereby tweaking the downforce. "You can get the car to ride closer to the ground, which increases your grip, or you can let it ride higher and faster. It's a very fine balancing act."
You can learn more about the Indy 500 at Littelfuse's Speed2Design site.
I totally understand the criticality of analyzing airflow to make tweaks to the car that will deliver a competitive edge. But what about employing 3D simulation software as opposed to or in addition to physical wind tunnel testing. Wouldn't simulation testing be easier and less expensive than putting the cars through their paces in physical wind tunnels? Do they not have the technology or are there specific reasons why the physical world still has an edge in testing at this stage of game?
Beth, in my experience, and that of others I talk to, the setting up of a model is very difficult and time consuming. This is especially true of something like an Indy Car. Considering the time between races and the ability to simulate the track with a device, it might be quicker to do it this way. On the other hand, when designing a large complex machine or one that will be made in large volume, the time is worth it.
Perhaps after getting driving rights for their autonomous cars, Google might look at autonomous race car operation. Machine accurate, faster-than-human measurements in all directions and consistent operation, it might provide an interesting man-vs-machine contest. If nothing else, the machine operated car could remove human support systems along with the human. The vehicle could operate closer to the limits.
UAVs have already revolutionized military aviation. Almost every other week or so, UAV launched missles attack our enemies in Pakistan and Yeman. The robot warrior is becoming a fact, at least in the air.
That's a very good point, Bob. If all of the variables the driver faces could be identified, they could also be optimized. The lag time between an event and a response would be quicker with a computer. That coule make all the difference.
Some day, that could happen, Rob. The problem with autonomous driving right now is so-called "rogue vehicles," i.e., cars driven by humans. Autonomous cars have trouble predicting the crazy things that humans do. If we could get all the humans off the course, I think it could happen.
Totally fascinating to me that this kind of ingeniousness and intelligence and creativity can be put forth for an entertainment venue.
But when it comes to something like perfecting the wind engine which could impact the lives of millions of people, no effort is put forth at all. Just a bunch of lemming stuff based upon a 1946 design found in the Bowels of the NASA drawing files.
When the magnificent Automotive Suspension Engineer, Bill Allison set out to see if he could hit the Betz limit, he did very methodically. And he became convinced that a confined flow wind tunnel produced supercharged, erroneous results so he created a non confined flow test environment. The results were amazing.
Yet idiocy persists, and the ethics of a profession are constantly called to question.
Not idiocy at all, Architect. Simulation is used as design shortcuts, not as final solutions. It works well to get to the finer tuning stage - then real life comes to play.
The wind engine is still a "pie in the sky" - it can't earn its own keep - even after the billions spent on research and pilot projects. It can't pass "real life". You can only "bang your head on the wall" for so long.
Don't be questiong the ethics of a noble profession because it cannot perform miracles.
By experimenting with the photovoltaic reaction in solar cells, researchers at MIT have made a breakthrough in energy efficiency that significantly pushes the boundaries of current commercial cells on the market.
In a world that's going green, industrial operations have a problem: Their processes involve materials that are potentially toxic, flammable, corrosive, or reactive. If improperly managed, this can precipitate dangerous health and environmental consequences.
With LEDs dropping in price virtually every year, automakers have begun employing them, not only on luxury vehicles, but on entry-level models, as well.
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