Can you guys give me some feedback on this thing I'm writing

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Can you guys give me some feedback on this thing I'm writing

Postby swank » Thu Dec 17, 2015 8:07 pm

Hi everybody. I'm doing a write up on the engine dyno I built for my senior design project last spring. Going to post it on gsrfab.com as we build that site out. The stuff below will be "part 1" of however many.

The kind of things I'm wondering:

Is the technical side appropriate?
Would you like more details or are there enough to give you a headache?
Did you learn anything?
Did you enjoy reading it?
Do you have any feedback I didn't ask about?
And lastly, did you find any technical errors?

With that, thanks and what you think?

Water brake engine dyno

So you think you want an engine dyno, huh? How handy would that be, right?? Have something you can throw an engine on to develop tunes, break in your new engine build, maybe test out some new fuels or something, right?

Well, strap in for some serious thinking. For my senior design project in mechanical engineering, I proposed to the class doing exactly that. After being joined by a few others, we set off on the project.

First, the research. I had pretty much made up my mind already that a water brake was going to be the easiest way to achieve our goals. BUT, that’s not how engineering works, so the team explored and learned about the different types of engine brakes (I.E., engine dyno). Some examples are: gigantic disc or drum brakes, huge electric motors that essentially act like gigantic heater elements (needing liquid or other cooling), one of my teammates even thought it would be acceptable to put an airplane propeller on the output shaft of the engine (it has been done before, after all). All of these options can be viable, but none of them met the “cheap, safe, clean, and cheap” criteria set up at the beginning of the semester. After much debate and learning, a water brake of the toroid type was decided upon. Turns out that toroid is the mathematical term for donut, in case you were wondering. There are patents as far back as the early 1800s for this type of device, the first one designed by William Froud to induce a load on a steam ship (a big one too). The first known toroid water brake was used to absorb 20,000hp, at 90 friggin rpm. Think about that for a second and let it sink in. The equation for hp is:

HP=(Torque∙RPM)/5252

After rearranging the equation to figure out what torque is needed to produce that much power, we get:

(HP∙5252)/RPM=Torque

Dropping what we know into this equation gives us:

(20,000∙5252)/90=1,167,111 ft∙lbs

All by spinning water around in a donut shape…

Second, HOW THE HELL DOES THAT WORK??

And HOW THE HELL DOES THAT WORK??? Well, sit back and prepare to be learned.

So if you remember anything about physics, you might recall that the “definition” of work is a force times a distance. I think they claim this came about from measuring how far a horse could drag a large bag of chips or something, and decided to rate everything from that moment forward based on this finding. So, to minimize your work, you will want to minimize both the force you apply and the distance that force has to be applied for. Take a basic water pump for example, like the kind irrigating the field over yonder. To be an efficient pump, it should take not very much work to run it (to move the water), right? As in, you don’t have to pay a bunch of money to the power company to pump a bunch of water (because it’s not doing much work). Well, if you have ever looked inside of a water pump (or maybe even a turbo?), you might have noticed there are blades in there that spin. The basic idea is that water usually enters in the center and travels in as straight a line as possible to the point of exit. This can be in less than one rotation of the pump even! The key point here though is that it’s traveling in a relatively straight line. That is what makes it efficient. By traveling in basically a straight line from inlet to outlet, in less than one rotation, the force being applied to the water to get it to move has been minimized. This is where blade shapes come into play, and people get PhDs studying that sthi. They are the ones squeezing a hundredth of a percent gain in efficiency out of some pump used to move chemicals in a plant somewhere, so that the company pays $3 less a year in electricity. And god bless em, because we get to use that tech for things like moving water through an engine block at the appropriate pace without creating a bunch of parasitic drag. But I digress…

To recap, a pump moves water (or any fluid really) in as short a distance as possible to reduce the work, needed to drive the device. As a side note, now is the time to introduce the idea of power, which is work times time. Phrased in another way, it’s work done over a period of time. Back to the horse thing about work, now they see how fast a horse can drag the bag of chips some set distance, an magically you have horsepower.

SO, say we wanted to make a device that we hook a big, high horsepower engine up to in order to determine just how much hp and or torque we gain (or lose) from duct taping magnets to the fuel line. If we hook up a plain old water pump to the drive shaft, we are going to pretty much have to be parked next to a lake because we are going to move a literal metric whAt? of water with that thing. That’s because a water pump is designed to move water from point A to point B using as little power as possible.

Are you beginning to see where this is going? If not, that’s ok. Anyway, to make a water brake instead of a water pump, we are basically going to reverse what we are building it for and turn it into the worlds worst water pump. Something that takes so much work to turn, that it can actually stall the engine/motor that is making it turn. Any guesses on how we might do that? If not, that’s ok, we are all learning here…

To make the worlds worst water pump, we are going to play with the distance thing and make the water travel as far as it possibly can from point A to point B. To visualize this, now would be a good time to go grab a donut. Seriously. You shouldn’t have to go far though, as there is probably one on the desk somewhere. Now grab something long and skinny, preferably not attached to anything (dental floss, shoestring, a long strand of hair, etc) and drop one end of it through the hole in the donut. Now, round and round we go, keeping the wraps relatively close together. I promise you will run out of your chosen long skinny stuff before you get halfway around the donut (unless you grabbed the wifes knitting or something, which won’t fare well with the glaze on the donut). At this point, you should be able to make the logical leap that the distance traveled in this manner will lead to the theoretical maximum possible distance traveled without the fluid (string/hair/etc) changing directions (which we don’t really want to do inside of the device, supposedly). You might also guess that this maximum possible distance is much, much, much greater than that of a normal pump.

NOW, we have talked about two ends of the spectrum with the distance aspect of things. Why haven’t we talked about the force aspect of things? Well, the forces involved in both situations are going to be close enough to the same that we can pretend that they are actually the same. A handy little trick used throughout an engineering education. We are going to assume the forces are the same for the worst pump and the best pump because they are both moving water through them, and the distance traveled is so much different that spending time on the forces would be like trying to figure out why some people by more shoes than others.
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Re: Can you guys give me some feedback on this thing I'm writing

Postby RCCUMMINS89 » Thu Dec 17, 2015 9:16 pm

Subscribing for later....... I'm being lazy to ready that much right now. But I definitely want to read it. :mrgreen:
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Re: Can you guys give me some feedback on this thing I'm writing

Postby Remps » Thu Dec 17, 2015 10:57 pm

Might wanna scour some old drilling rig boneyard for a hydrostatic brake/drum assembly, could possibly concocted to work for cheap somehow.
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Re: Can you guys give me some feedback on this thing I'm writing

Postby 1STGENFARMBOY » Fri Dec 18, 2015 12:23 pm

All the water brake dyno's i have had tractors on work well enough but cooling the water is the only problem, usually they just run fresh cool water in and exaust the hot on the ground.

thats all i have about that.....Forest Gump.
93 W250 STD CAB, AUTO 3.55, GAUGES, 80HP DDP STICKS, DENNY T ,16CM HOUSING, 60MM GILLETT, VE MAXED,BHAF, BHFF, 366 SPRING,P/S INTERCOOLER, TIMS COOLER TUBS, TIMMING 1/8 BUMP,4in TURBO BACK TO DUEL 5IN STACKS,33 12.50 BFG, HOLLEY BLACK, CONVERTER COOMING.
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Re: Can you guys give me some feedback on this thing I'm writing

Postby 1STGENFARMBOY » Fri Dec 18, 2015 1:05 pm

One more thing from my non engineering background, i could see it beeing a problem if turning the inpeller at a high rate of speed feed large enough volume of water to keep it from cavitating,

we use a large gate valve on a plate of steel to dead head the 95hp pumps we rebuild to load test them, we are really only testing the full load amp draw on the motor part of the pump, not really the performance curve of the pump itself.
93 W250 STD CAB, AUTO 3.55, GAUGES, 80HP DDP STICKS, DENNY T ,16CM HOUSING, 60MM GILLETT, VE MAXED,BHAF, BHFF, 366 SPRING,P/S INTERCOOLER, TIMS COOLER TUBS, TIMMING 1/8 BUMP,4in TURBO BACK TO DUEL 5IN STACKS,33 12.50 BFG, HOLLEY BLACK, CONVERTER COOMING.
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Re: Can you guys give me some feedback on this thing I'm writing

Postby swank » Fri Dec 18, 2015 1:38 pm

The dyno is already built, I'm just writing up a description of it. Just looking for feedback on the writing part. Does it make sense, etc?

Thanks guys!
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Re: Can you guys give me some feedback on this thing I'm writing

Postby fatty » Fri Dec 18, 2015 4:05 pm

Made sense but I thought it was just a bit too casual. When I read something informative like that, I don't really want the little extra bits in there. My opinion of course.
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Re: Can you guys give me some feedback on this thing I'm writing

Postby swank » Fri Dec 18, 2015 5:23 pm

fatty wrote:Made sense but I thought it was just a bit too casual. When I read something informative like that, I don't really want the little extra bits in there. My opinion of course.


Cool, thanks for the feedback!
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Re: Can you guys give me some feedback on this thing I'm writing

Postby BC847 » Fri Dec 18, 2015 7:53 pm

I tend to agree with Fatty as that aspect gets almost to the point of distraction.

At the risk of appearing a simpleton, staying with the current presentation, pictures of that you describe would be of help.

Image
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Re: Can you guys give me some feedback on this thing I'm writing

Postby Richie O » Sat Dec 19, 2015 10:57 am

I guess it depends on what audience it is intended for. I myself need to have terms simple, as my technical dictionary is very limited. I guess you could say Im a couple short of a dozen. :mrgreen: I build my own antennas for ham radio. I could throw a bunch of technical terms to advanced radio geeks, or keep it simple for intro level people.
1989 W250 727, 3.07 L/S, S300, P/S Intercooler, Stans exaust, Pump adjustments, 127k miles,297 hp
1993 W250 extended cab, rag, 4.10 l/s, 6x16's, HTT 62/71/14 piston l/p, Isspro EV series tach, fuel pressure, boost, oil pres, water temp, volt, pryo, 132k/ 301 hp
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Re: Can you guys give me some feedback on this thing I'm writing

Postby BC847 » Sat Dec 19, 2015 1:16 pm

Richie O wrote: I build my own antennas for ham radio. I could throw a bunch of technical terms to advanced radio geeks

Oooooooh. I like to build yagis. Was a while ago listener via some Heathkit equipment. 8)
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Re: Can you guys give me some feedback on this thing I'm writing

Postby Richie O » Sat Dec 19, 2015 4:22 pm

73 de KC1DVL QSY to 14.313 or --... ...-- -.. . -.- -.-. .---- ...- .-.. --.- ... -.-- - --- .---- ....- .-.-.- ...-- .---- ...-- for you morse code guys. :mrgreen: Disclaimer,,,, I did cheat on a few characters. Not quite ready for code yet. My longest contact is 2 stations in Japan. Almost 10,000 miles on my antenna at 100 watts. Talked to Italy on just 5 watts. 8) Wire center fed fan dipole resonant on 20, 40 and 80 meters. Have talked to 42 different countries so far. Now back to swanks topic,,,, sorry. :oops:
1989 W250 727, 3.07 L/S, S300, P/S Intercooler, Stans exaust, Pump adjustments, 127k miles,297 hp
1993 W250 extended cab, rag, 4.10 l/s, 6x16's, HTT 62/71/14 piston l/p, Isspro EV series tach, fuel pressure, boost, oil pres, water temp, volt, pryo, 132k/ 301 hp
1992 W250 with NV4500, 3.54's, 16cm 60mm GDS H1C, ground stock cone, Isspro tach, pryo, boost, fuel pressure, slow, rusty, dented,180k
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Re: Can you guys give me some feedback on this thing I'm writing

Postby swank » Sat Dec 19, 2015 10:07 pm

Richie O wrote:73 de KC1DVL QSY to 14.313 or --... ...-- -.. . -.- -.-. .---- ...- .-.. --.- ... -.-- - --- .---- ....- .-.-.- ...-- .---- ...-- for you morse code guys. :mrgreen: Disclaimer,,,, I did cheat on a few characters. Not quite ready for code yet. My longest contact is 2 stations in Japan. Almost 10,000 miles on my antenna at 100 watts. Talked to Italy on just 5 watts. 8) Wire center fed fan dipole resonant on 20, 40 and 80 meters. Have talked to 42 different countries so far. Now back to swanks topic,,,, sorry. :oops:


LOL, you guys are hilarious.

So your previous post means that you think the terms are appropriate? Or not so much? Did it all make sense? My intention is to be as widely applicable as possible, if catered to anybody, it would be towards people with very little knowledge of these kinds of things.

Folks who are looking for more technical info have a lot of that at their fingertips these days.
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Re: Can you guys give me some feedback on this thing I'm writing

Postby swank » Sat Dec 19, 2015 10:09 pm

BC847 wrote:I tend to agree with Fatty as that aspect gets almost to the point of distraction.

At the risk of appearing a simpleton, staying with the current presentation, pictures of that you describe would be of help.

Image


Pictures will definitely be heavily used in the final product (and remember this is very much in draft form). So you'd rather have more of an actual technical paper?
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Re: Can you guys give me some feedback on this thing I'm writing

Postby meby » Sun Dec 20, 2015 6:52 am

How do you collect data off this thing?
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-Speedex Walking Tractor.
-BCS Walking Tractor


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