Fuel efficiency

[Jack Gifford]

Can you guess the purpose of the pictured contraption?

I recently read a Hot Rod Magazine article from 1974 about Autotronic Controls Corporation (ACC) research into using ultrasound to reduce fuel droplet size of an engine's air/fuel mixture. Their prototype system also included closed-loop mixture control via an oxygen sensor and computer-controlled fuel injection- a precursor of today's technology. But I was intrigued by the ultrasound function and its potential efficiency gains. Fuel droplets in the A/F mix from a carburetor (and also from their fuel injection) are about 40 microns diameter. The ultrasound reduces their diameter by a factor of 10-20; but this reduces their mass by diameter-cubed, so mass is reduced by a factor of 1,000 - 8,000! Think about that- no more A/F ratio changes nor cylinder-to-cylinder variations due to twists and turns of the intake manifold. Not to mention the more complete combustion in the chambers.

So... upon seeing that I could buy an ultrasonic transponder complete with circuit board for $11, I've embarked on DIY ultrasonic experiments. The cobbled together pieces are a rough approximation of a log-style intake manifold and 1-bbl side-draft carburetor (water instead of fuel for safety) with transponder below the "carburetor" and air flow created by a vacuum cleaner drawing on the end of the "manifold" through a clear hose for viewing the mixture.

Nothing learned yet, except that my "carburetor" is way off- it instantly floods the manifold with water. I need to create some smaller "main jets" than the .063" that I used.

To be continued.......

[Historical trivia: As ACC began having success with the A/F mixture, they had a need for better ignition and developed the first multi-spark-discharge system. The ignition sold so well that they changed the company name to MSD!]

[POPS]

Mr. Gifford,
Very interested in your microwave droplet experiments.  Check out my page on Facebook, Don Jackson Engineering.  I manufacture impact nozzles that have produced spectacular results. We have almost 100 qty of .024 impact nozzles in the Flashpoint streamliner. 
Things we have observed:
Total EGT spread 35 F.
EGT's average 850 F.
2 psi boost increase, (better sealing).
Dropped manifold temperature 20 F.
Almost zero nitro in the oil.
75 HP gain in fathead alcohol motors.
Seems to me that microwave power could be reduced significantly if the droplets are already small. Close to a change of state which would really
cool the charge.  Ridiculous power gains.   
Don Jackson

[Jack Gifford]

Shade tree research can only go so far, and I've pretty quickly struck out. I'm not equipped to evaluate the droplets in the fuel/air mix. I tried a large clear expansion chamber, and added red food coloring to the "fuel" (water), but any effect on droplet size still isn't visible. I can confirm the potential for ultrasound, since placing a single drop of water on the transponder creates about a half cubic foot of "fog". My other problem is that my physics skills are too rusty- I can't even estimate the energy required of the ultrasonic waves to "break up" a given mass of fuel.
I'll keep searching for any possible successful attempts. I wasn't able to learn why ACC didn't follow through- anybody know why?

[Jack Gifford]

Don- I'll have to look at your impact nozzle information. Any idea of droplet size (gasoline)?

[POPS]

Jack,
I have not measured the droplet size.  Found a company in Michigan that has a laser based particle size machine that can do it.  A bit pricey will try to get it done later this year.  Particle size is a bell curve distribution so who knows?  When I hold a nozzle 5ft above the floor the spray will not wet the floor.
Don

[tortoise]

Think about that- no more A/F ratio changes nor cylinder-to-cylinder variations due to twists and turns of the intake manifold.

I'm thinking about it, but don't follow. Why do low-mass droplets change direction more readily?

[John Burk]

In the Bill Pitts Surfers series Tom Jobe tells about how their 200 psi fuel pressure / fine atomization helped their top fueler . Less detonation , much less fuel required (they could run 100% nitro with the limited flow of a Hilborn 175 pump when when everybody else could only run 75% without going lean" and other benefits .

[jacksoni]

Think about that- no more A/F ratio changes nor cylinder-to-cylinder variations due to twists and turns of the intake manifold.

I'm thinking about it, but don't follow. Why do low-mass droplets change direction more readily?

Nothing moves without a force applied and as some of the fuel becomes a gas in the intake and the rest in the cylinder, a smaller droplet or a gas takes less force to move (change direction).

[Darcane]

Who is the author on the original article?

In college, (New Mexico State University circa 1998) I had a college professor that was working on a way to better atomize fuel to improve fuel efficiency.  IIRC, he had a SBC running around 20:1 AFR under load on 87 octane fuel.  He was an old hot rodder from the 60's named Dean Hill and occasionally wrote articles for Hot Rod magazine. 

Mike

[tortoise]

Nothing moves without a force applied and as some of the fuel becomes a gas in the intake and the rest in the cylinder, a smaller droplet or a gas takes less force to move (change direction).

Well, that doesn't explain it, but I think I've got it. A smaller droplet would take less force to move it, but would also have less force exerted upon it, by virtue of having a smaller surface and frontal area. In fact, the surface/volume ratio, and thus the drag/mass ratio, of a smaller droplet is higher. Thus, it's more likely to go with the flow.

[John Burk]

In about 1972 the Patent Gazette showed a fuel injection design somebody patented that vaporized the fuel by passing it across an electrically heated plate .

[RichFox]

You might want to talk to Don Jackson, He makes and sells injection parts that run around 400 psi, Many really trick nozzles and a very fine spray. Or look at the Rage fuel pump web page. They sell his stuff

[Jack Gifford]

Darcane- the author of the article was Jim McFarland, but Jack Priegel (of ACC while it was still a privately held company) was the developer.

Yes, Dean Hill did a lot of development of performance parts.

I doubt I'll learn much, but since it looks fairly easy... I'm almost done "implanting" the ultrasound device under the carburetor of the 6-cylinder in my Falcon.

[Jack Gifford]

In searching the web, I found a paper presented at a 2015 Icelandic design conference that described successful design and testing of an "Ultrasonic Carburetor" on a single-cylinder 170cc engine. I have yet to finish reading it.

[edinlr]

This topic was interesting so I had to send a message to my buddy Darin Morgan.  For those of you who don't know, Darin left Reher-Morrison last year and has joined MAST.  I figured if anyone could speak on authority it would be him.  I'll try to get the short version to report back.‎

Ed Holman‎ to Darin Morgan
1 hr ?
Darin, glad to see that you are still alive. I have a quick question that is being discussed on the landracing.com site about fuel particle size. Is there anything to this? http://www.landracing.com/forum/index.php?
Fuel efficiency


Darin Morgan Yes, there is a lot to it. I knew Dr Dean Hill for decades. We have designed them, used them and found out a lot about ultrasonic atomization. Way to much to go into here but give me a call. I will fill you in on all the pitfalls