On 3/16/2014 2:17 AM, rotaryeng wrote:
Mercedes won, Redbull was second And McLaren was third. Many cars
dropped out with engine trouble as the new turbo V6's are very
complicated indeed. They don't call it turbo compound but "energy
recovery". That is because a large percentage of time a road racing
car is under braking and one want's to recover that energy as well
as waste exhaust energy.
That braking energy recovery does not help at all on the freeway
or autobahn. It just adds a lot of unnecessary weight.
The exhaust energy is recovered by a shaft coming out the turbo
charger compressor driving a generator. This charges a battery.
Similar to the attached 3D.
This is not an efficient way of doing it in a passenger car. Say
the generator is 90% efficient and the motor is 90% efficient over
all energy recovery is then only 81%.
Again the battery is just more dead weight. Typically the
electronc controller could also be 90% efficient so over all
recovery efficiency could drop to 73%. All this waste heat heats up
the engine compartment.
There is no beating a gear box between the exhaust turbine and the
crankshaft. That would be 95% efficient or higher.
The battery is also charged from the retarding force on the rear
wheels under braking in a road racing car. These generators also
serve as motors that provide extra torque under acceleration and in
the case the turbo charger generator it is also used in electric
motor mode to accelerate the compressor. This reduces the notorious
turbo charger throttle lag.
One can imagine this is a programmers worse nightmare. Not only is
the competition among the drivers and engineers but now
programmers are competing to see who can write the best control
program. I wonder what chip they are using? I would not be a bit
surprised if it was an ARM variation of some sort.
That is like using your cell phone to control 800 HP :)
The generator connected to the compressor shaft is interesting as
it must be geared down as the turbo is turning at 125,000 RPM. An
electric motor would probably blow up due to centrifugal loads on
the copper windings if it were to run at 125,000 RPM.
Or they good be using switched reluctance motor with no
windings on the rotor.
http://www.rotaryeng.net/Oxford-640-4802.wmv
Paul Lamar
Nice writeup, Paul. Do you think they have made it complex (and
expensive) enough? I am not enamored by the V6 exhaust note.
Gary Knutson
Thanks Gary.
I am about to blast them on that silly narrow rear wing.
The vast majority wing drag is induced drag. They would get along with a
lot less
fuel if they doubled the width of the rear wing.
"In aerodynamics, lift-induced drag, induced drag, vortex drag, or
sometimes drag due to lift, is a drag force that occurs whenever a
moving object redirects the airflow coming at it. This drag force occurs
in airplanes due to wings redirecting air to cause lift and also in
cars with airfoil wings that redirect air to cause a down-force."
The wing induced drag factor is equal to the lift coefficient squared
divided by
pi times to aspect ratio. Aspect ratio is width divide by cord.
In Formula 1 cars aspect ratio is about 2.
So the current induced drag factor is about 0.16.
If they doubled the width and kept the down-force the same
it would be one divided by four times pii or 0.08. In other words, half the
wing drag.
That is why they get those enormous vortex's off the wing tips
in the rain.
Assume the current wing area is 4 square feet and C sub l is one. The
down-force
at 150 MPH is 52 time 4 or about 200 pounds. Drag is then 32 pounds.
150 MPH is 220 FPS. HP consumed by the wing is then 7040 foot pound second
or 12.8 HP. That is roughly 8.3 pounds of fuel burned, per hour, by
the wing alone.
The slotted wing down-force is probably double that so that number could
be as
high as 33 pounds of fuel per hour. Rough calcualtions all. Two hour race
66 pounds less fuel. The current F1 fuel limit is 220 pounds.
The high end plates help but they have their own drag associated with them.
Here is my resume :)
http://www.rotaryeng.net/AIAA-Paper.pdf
http://www.rotaryeng.net/Oxford-640-4802.wmv
Paul Lamar
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