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.
Chaschas you sould do a little research as windgenerators do earn their keep and profits nicely.
Please don't confuse the finacial vehicles known as wind farms with whether wind is viable. Facts are in many places wind is the low cost energy source and those using it are paying lower costs. A recent utility study forcast that wind in the mid to west will keep the cost of electricity down. Afterall it only takes 2kw of wind generator to power an eff home and tetail they are going for $2k/kw in larger sizes.
Facts are now solar PV, Solar CSP/CHP, wind are all now under $2k/kw or will be soon. At that pricepoint it's less costly than retail coal.
As for Indy Aerodynamics it's mostly used for downforce and using hp to overcome the large aero drag it causes. It's a very hard thing to design because things like paint lines have brought down airplanes and air coming out sideways from the racecar, etc create all kinds of problems.
I depend on weight, low CG to keep me stuck to the earth and just use aero to lower drag to increase range.
Bill Allison discovered that his best configuration was with 10 blades, dead flat, highly polished, 8deg, in a 12 blade configuration was best.
He would talk about a cone of resistance which you couldn't see until he got a hunk of dry ice in a baking pan with water. Then you would see this nacelle like a P-51 nose cone show up with the 12 blade config. He would point out that to be an area of high pressure and that the oncoming wind would circumvent and avoid it hence losing efficiency. When he removed two blades directly opposite of each other the cone would instantly disappear and he said that the condition was in place to pull the most power.
So something similar must happen when 3 cars are abreast. The air in front must copress to some degree and a car lagging a little behind would suffer from having to battle the compressed oncoming stream.
The issue then would be how to insure that the air directly in front of one car would becontained and related to that car rather than shunting it off and making it much more difficult to the competitor. That almost insinuates flat fins on eather side of the vehicle forcing the air over the top rather than trying to buffet your neighbor.
This article just underscores how much aerodynamics have created parades rather than races. With the incredible emphasis of creating a car that can be driven flat out all the way around Indy, driver skill is secondary. If you look at an Indy or F1 car there are all sorts of wickers, splitters, trim tabs, diffusers, flaps, etc. designed to keep the car glued to the road with minimal drag. Unfortunately this creates unpredictable handling when running close to other cars so there is no way to pass unless one car is a lot faster (i.e., less drag) than another. I would really like to see substantial limits on aerodynamics, including an outright ban on wind tunnel testing, so that driver skill and the ability to pass are brought back into racing.
Seems lke we went to different engineering schools Frank.
The increse in efficiency from <20% up to 59% represents a 300% increase in my book.
Not worth looking at? Not one fine engineer capable of examining this in all of the world?? Not one creative and competent engineer willing to take another look?
Other issues?? What other issues? There always are other issues. Sure the wind doesn not blow constantly everywhere. But in some places it is very important.
Perhaps these men with their wonderful discoveries could push that limit. Maybe they could beat Bill.
Look at the beautiful Indy Cars with their all sorts of fins and scoops, they are examining and learning things that will benefit the broad section of humanity.
And I am curious now about that wind tunnel... how does it simulate the disruptive flow with 3 cars racing side by side? And what about crosswinds?
Air seems to be a fickle lady that seems to take the path of least resistance and it will compress in front of an obstructive object.
But I tend to think that one does have to be clear about their focus and intentions. Development forces that.
I wrote that Allison hit the Betz limit. That is 59% efficient.
The current 3 bladed fans achieve less than 20% efficient.
From an engineering perspective, what kind of improvement is that?
From what I have witnessed, engineers will kill for a 3% increase in efficiency.
Those dufus 3 bladed flying fans were known by Bill to be bogus over 30 years ago. Yet the engineers persist on the wrong path without any sort of proper testing and development and no one has stopped to understand that it's not the principle of flying but the principle of resisting that extracts the greatest amount of energy from the wind.
Ever hear of a spinnaker, or a parachute, or a windmill? They resist to extract the energy.
So Buford, in saying that he lost $150,000,000 on his farm was destined to lose because he followed some of those engineers who were advocating the very poor design approach.
You mention all sorts of testing. Where? There virtually has been none. There really is no testing and development facility that is objectively examining this issue anywhere in the world. Was Bill lying? I don't believe that at all.
As a 73 year old Architect who co-oped at the Corporate Engineering Staff at the GM Tech center, while attending GMI, I am aware of what it takes to develop something properly. And I have witnessed many lying engineers in my life, particularly those wedded to the political world.
And I have witnessed similar things in the Architectural world
No profession is completely and inherently noble. To be sure there are magnificent efforts like those of Sam Williams and Bob Lutz and Burt and others but politics seems to muck things up very quickly.
Actually Robinson Helicopter could solve the issue. They know how to set up a non confined air flow wind "tunnel".
A field of only autonomous cars may happen some day, Chuck. That would certainly showcase the quality of the inidividual vehicles. Remote control might be an option as well.
Bill (Architect), I won't disagree that "the way we've always done it" often wins out over creativity and methodology and I'm also no aerodynamic expert, but I would argue that such an exhibition like that of Watson could help fund research that would potentially benefit millions of people...
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.
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.
For 3D printing to make the jump from rapid prototyping to manufacturing, engineers will need to find easier ways to move products from their CAD screens to their printers.
Gigabit and PoE are two networking technologies moving ahead in tandem as industrial users power remote Ethernet devices such as IP security cameras at 1,000 Mbps over existing CAT5 cable.
New versions of BASF's Ecovio line are both compostable and designed for either injection molding or thermoforming. These combinations are becoming more common for the single-use bioplastics used in food service and food packaging applications, but are still not widely available.
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