New projects for this year.

[dwilfong]

I figured i would post this here because it has to do with Eng.

I have decided to build some testing equipment this year.

A Eng Dino and a flow bench.

Would like to here from those that have done this to help with my quest.

What I have planed for the flow bench is a two Chamber box. the top part will be made out of clear plastic so I can flow carbs and see what the atomization looks like.

Have talked with Bruce at Flow bench Tech and he is making a plate that will flow 25CFM at 28" of water.

The upper box will have a deflector cone above the plate hole to deflect the wet flow and separate the fluid in to the upper box to be drained at a later time.

I will use a shop vac with a simple speed control to set the vacuum at 28" in the lower box and use a v tube set up to check the differential between the upper and lower boxes.

I will use this set up to also check flow changes thew the case.

Next will be the Dino.

I am planing on using a brushless motor to load the Eng. Mounted in a floating cradle with a load cell attached to it.

A bridge rectifier will change the 3ph AC out put to DC current. then using a load system of resistance to still be determined will load the motor.

All reading will be logged using the Eagle tree logger. this will include RPM,EGT,head temp and reading from the load cell. Thy will all be logged in real time on the same graft and in Excel spreed sheet form.

Any input will be more than welcome to help with this project.

David

 

[Tim_Duggan]

Found this on another site ( http://www.eng-tips.com/viewthread.cfm?qid=84432) and thought you may find it useful;

A very easy way to build an eddy current brake is to just use any ac induction motor, and feed dc current through the windings. It only works for low power engines though, because the solid steel (squirrel cage) rotor does not dissipate heat well.

But if you are experimenting at home with very small engines, it is a very practical ultra low cost way to do it.

A three phase motor will have three terminals, just feed a dc current into any two terminals, and ignore the third. The rating plate will have a current rating for the motor, which should not be exceeded.

Only a low dc voltage is required because the resistance of the windings will be quite low. Also the braking torque will be extremely high, even at currents far below the maximum on the nameplate.

With a given braking current, the required torque to turn the motor increases very rapidly with speed. A given motor will brake full rated torque at its slip rate, which might be only 150 RPM.

Just to explain this, if the mains frequency is 50Hz, the magnetic field inside the motor rotates at 50 x 60 = 3000 RPM. The motor speed might be rated at 2850 RPM, so the slip will be 150 RPM.

If you try to spin it faster than 150 RPM with full field current, it will readily sink far more torque, so a small electric motor can easily hold almost internal combustion engine. But the big problem is heat buildup in the rotor. It will get very hot very fast, so that is what limits the power absorption, not torque sinking ability.

So, a single or three phase induction motor would make a nice home chassis dyno for a cart or small bike, provided you were careful not to cook it. A large external blower or submerging the whole thing in oil might also work.

It is all a bit Mickey Mouse, but some of us are not that wealthy. Short power runs are all you really need with long cool down periods for home use. Also, excessive RPM and heat might cause it to fly apart, so a bit of caution is required.

Try it yourself, get a quarter horse or larger single phase motor, and while turning the shaft by hand, apply 12v dc and see what happens.

 

[dwilfong]

Found this on another site ( http://www.eng-tips....d.cfm?qid=84432) and thought you may find it useful;

A very easy way to build an eddy current brake is to just use any ac induction motor, and feed dc current through the windings. It only works for low power engines though, because the solid steel (squirrel cage) rotor does not dissipate heat well.

But if you are experimenting at home with very small engines, it is a very practical ultra low cost way to do it.

A three phase motor will have three terminals, just feed a dc current into any two terminals, and ignore the third. The rating plate will have a current rating for the motor, which should not be exceeded.

Only a low dc voltage is required because the resistance of the windings will be quite low. Also the braking torque will be extremely high, even at currents far below the maximum on the nameplate.

With a given braking current, the required torque to turn the motor increases very rapidly with speed. A given motor will brake full rated torque at its slip rate, which might be only 150 RPM.

Just to explain this, if the mains frequency is 50Hz, the magnetic field inside the motor rotates at 50 x 60 = 3000 RPM. The motor speed might be rated at 2850 RPM, so the slip will be 150 RPM.

If you try to spin it faster than 150 RPM with full field current, it will readily sink far more torque, so a small electric motor can easily hold almost internal combustion engine. But the big problem is heat buildup in the rotor. It will get very hot very fast, so that is what limits the power absorption, not torque sinking ability.

So, a single or three phase induction motor would make a nice home chassis dyno for a cart or small bike, provided you were careful not to cook it. A large external blower or submerging the whole thing in oil might also work.

It is all a bit Mickey Mouse, but some of us are not that wealthy. Short power runs are all you really need with long cool down periods for home use. Also, excessive RPM and heat might cause it to fly apart, so a bit of caution is required.

Try it yourself, get a quarter horse or larger single phase motor, and while turning the shaft by hand, apply 12v dc and see what happens.

Tim you are the man.

This looks like the answer to the problem in a very simple solution.

The motor will have a very big water cooling jacket.

Tyler posted a pick of a Dino that he uses and it has the motor built in to the cradle with water cooling to it.

I am planing on basing my build on this design.

This kind of build will pull lots of heat from the motor with a closed loop heat transfer coil running in ice water.

 

[dwilfong]

as far as your flow bench david i would use a venturi style vacuum driven from an air compressor

that way its infinatly adjustable via an air regulator

Greg I will look into that setup and see what is involved.

I have a small air vacuum pump that I use to suck down the AC systems in the trucks I work on.

Already have a 5 hp shop vac. and a 120v 15amp router speed controller is only $30.

Great input from all thanks.

David

 

[dwilfong]

you wont need the vac pump i was a hvac tech many years ago so i know just what that is take a look at these http://www.thepartsb...099_rpr_-d.html

http://www.ebay.com/itm/Festo-LS-Compressed-Air-Vacuum-Cleaner-1982-Vintage-New-in-Box-/271150764107?pt=LH_DefaultDomain_0&hash=item3f21d8504b

What ya think?

 

[lohring]

The big question with a flow bench is what are you going to study and test. The problem with two strokes is that the flow is not steady and often reverses. As far as I know, this means flow benches aren't going to be useful for predicting scavenging performance.

We used a flow bench to look at carb flow. it was very instructive. Others have used them to get an idea about transfer flow, transfer flow matching, and transfer flow direction. Water from a hose has also been used. People have even built pulsating flow benches. The work of Jante and Gordon Blair studying scavenging efficiency can give an idea of how to study scavenging. As far as I know, only expensive computer flow simulations can approach their results using simple mechanical test beds.

Below is a setup we used for carbs. We sucked air through a Quickdraw cylinder that served as a carb mount.

Lohring Miller

 

[dwilfong]

The big question with a flow bench is what are you going to study and test. The problem with two strokes is that the flow is not steady and often reverses. As far as I know, this means flow benches aren't going to be useful for predicting scavenging performance.

We used a flow bench to look at carb flow. it was very instructive. Others have used them to get an idea about transfer flow, transfer flow matching, and transfer flow direction. Water from a hose has also been used. People have even built pulsating flow benches. The work of Jante and Gordon Blair studying scavenging efficiency can give an idea of how to study scavenging. As far as I know, only expensive computer flow simulations can approach their results using simple mechanical test beds.

Below is a setup we used for carbs. We sucked air through a Quickdraw cylinder that served as a carb mount.

Lohring Miller

I will try different things. Wet carb flow for one. the flow of actual air thew the carb will change with fluid suspended in the stream.

I did a small experiment last night with the shop vac and the carb and back plate off my CMB 1.01 it was a prefect fit to seal.

was looking at the stream coming out of the spray bar. now I hook the carb to my needle and to a tank then hooked my BM flow meter to the tank to pressurize the system.

It did not take long to suck the tank dry.

the flow was much more than the eng will produce so it was not a good test.

This lead to my disunion to build the bench.

Also I can tell the flow of fuel with a graduated cylinder for the tank.

This will give me a wet airflow rate and a fuel rate.

Testing and seeing what dose what is what I am looking for not definitive numbers. It will be a learning tool.

Being able to remove the liquid from the stream in the box will give a wet flow number.

Also flowing the case will help with port sizing. checking the intake and ex in separate wet flow test will give a ratio. Also it will let me know if the carb can support what the case can flow.

Not to say that this is a definitive number but will be used as a guide line.

Relationships are what I am looking for. This is the bases of all theory.

Not sure what it will tell me but I will have a tool to work with.

David

 

[dwilfong]

Found this in the shed. knew I would use it for some thing.

Cheep old glass bead cabinet. Pulled it apart and will replace all the pop rivets with bolts and seals. Reseal every seam and put plates over the holes.

The two big holes in front will be the working ports. can make different adapters to fit any thing.

Will put a box in the box to attach the flow plate on. plenty of volume to separate the liquid from the air. the tray will hold the liquid with a drain on the bottom.

Mount the tubes on a board and attach it to the top.

Thinking of putting the blower on the back to make it self contained. will see how it progresses.

Want to keep the build under $200.

David

 

[Tim_Duggan]

Blasting cabinet for a flow bench / atomisation tester - I like it!

Are you planning on pressurising the fluid at similar rates to that of a pipe pressure system, or just rely on the venturi to draw in fluid. I would think it would have to be pressurised progressively to exactly the same rates as an engine on pipe which is determined by stinger diameter and pipe design to make sure the atomisation is the same as in a boat.... The dyno would be handy to get carb position to tank pressure references from!

 

[Tim_Duggan]

David,

Your comment about working on trucks gave me another idea - which whould be to find a truck retarder and use that as a brake. Low voltage, high current though and a lot more electrickery and bulk than the AC motor on DC.....

 

[dwilfong]

The test that i did with the vac sucked the fluid right out of the tank with no pressure on it.

like the float chambers thy use over seas.

When I put the pressure to it, it really started to flow.

The Dino will give me a test stand to check the pipe pressure.

It looks like with a large spray bar no pressure will be needed to draw the fuel using a float chamber.Just using the pipe pressure to fill the float tank.

Jack St.Clair here in FL Dis 3 runs his scale with a .67 in it and uses no pressure tap.Draws the fuel right from the tank. no hopper. The tank is higher than the carb. His boat is real fast. wins almost every race he enters.

the residual pressure in the tank will mess with the needle flow I am thinking.

that is what I will explore with this setup.

Putting the needle right on the end of the spray bar and using Ex gas temp to control it.

The Brush less motors are not that expensive to test with. Will start there. Also the rotor mass is low not absorbing power thew inertia.

I think this will give a more realistic test closer to what the Eng will see in a boat.

Using the eddy current as a progressive load.

 

[j whiddon]

Sounds cool David. I'm really interested in your flow bench. I was trying to come up with a way to flow carbs and spray bars. Keep us posted.

 

[dwilfong]

im working on a similar setup for a flow bench

david the vac on ebay looks good

You know the more I think about it that would make a good vac. could flow real fuel mix and not blow up. :huh:

As long as I put my cig out first. :lol:

can any one interpret the flow Numbers to CFM ?

Needs to be over 25 CFM to work with the 25 CFM plate.

Got it 14 CFM will not work!

 

[dwilfong]

http://www.anver.com/document/vacuum%20components/vacuum%20generators/QVP%20Generators/q-vdf375!.htm Found this but it takes 29 CFM at 80 PSI to run it.

Have a rol-air v4 air compressor set up I use and this is at the top of its range of 32 CFM. It will never shut off while testing.

Takes a 220v 7HP motor to turn my pump.

And I bet this is not a cheep vac!

 

[dwilfong]

My bad looked at it better. It will work.

45 CFM suction. 14 CFM input.

David

 

[lohring]

You could use a mist system to spray either water or fuel into the transfers to study steady state flow. A friend used a standard coolant mister and a UV light with dye to do this. He made a transparent piston and head to see the flow. He felt the view through the piston was the best.

Lohring Miller

 

[dwilfong]

You could use a mist system to spray either water or fuel into the transfers to study steady state flow. A friend used a standard coolant mister and a UV light with dye to do this. He made a transparent piston and head to see the flow. He felt the view through the piston was the best.

Lohring Miller

That is what I was thinking . Checking wet flow thew the case.

I was thinking about the clear head but the clear piston now that is intriguing.

I will use the carb as the mister as that is how the Eng will run.

Have a feeling the flow characteristics will be different wet than thy are dry.

Have bin talking on a other forum for engineers that Tim turn me on to about the Dino.

It looks like a Delta wind motor with a single phase load across the windings will work.

Just hook restive load across the wires coming out of the motor.

No rectifier or any thing else just resistance.

It will produce a load 2/3 of the motors rated power.

Still talking with them about this will see where it leads.

Sounds to simple to be true. But if it works it will be the bomb.

 

[lohring]

I finished the mechanical parts of the eddy current brake dyno. So far it turns 30,000 rpm peacefully sitting on the counter. The magnets really brake the disks. I'll hook up everything, calibrate the load cell, and start real testing.

Lohring Miller

 

[Terry Keeley]

I finished the mechanical parts of the eddy current brake dyno. So far it turns 30,000 rpm peacefully sitting on the counter. The magnets really brake the disks. I'll hook up everything, calibrate the load cell, and start real testing.

Lohring Miller

Nice work!

 

[dwilfong]

That looks great Lohring!!

What load cell is that?