Pressure Gain Combustion (Now Proven)

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Eric
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Re: Pressure Gain Combustion (Now Proven)

Post by Eric » Thu Aug 14, 2008 9:49 am

If you have a specalist that acts like breaking a turbine rpm record is a good thing, it might be a good time to get a new specalist.

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Re: Pressure Gain Combustion (Now Proven)

Post by luc » Thu Aug 14, 2008 12:52 pm

To my way of thinking, running it without load is a "yes, but why?"
You're question is very pertinent Mike ... And the answer at this point would just be "Because it was the preliminary test" ... No other reasons, but you're right and we will load it today.
And why risk your turbine at this point?
No perticular reasons I would say, except that we (GLC & the turbo suplier) are curious to see up to what speed this turbo can reach and especially, how much rotation our engine can spin that turbine. But here too you are right. Although we want to push some limits here, I promiss I will do it wisely ... He he he :wink:
A simple dyno can tell you what power you have to work with at some throttle level, and then it's easy generating a power curve
True ... But don't forget that this power curve will be very different when taken directly at the turbine shaft and then, taken at the gearbox shaft. Imagine what torque a 10:1 reduction gearbox would give when at full power. But yes, your suggestion is good. The problem now, is finding the Dyno that will do this, which I believe will be easier finding a Dyno that can take 10,000 rpm then one capable of 100,000 rpm.
Having the compressor on there, and restricting the output of that will let you read torque at rpm
Also true ...
Torque can be read at the compressor housing with literally a torque wrench
This is where you are wrong budy. In such application, "Speed or RPMs" are crutial to get torque. Let me put it this way ... Years ago up north during extreme winter cold conditions, we use to help turboprops to start by holding the prop in our hand so the power turbines would not turn so the engine's temp would rise rapidely. It was really easy to hold that prop since nothing was turning, but once the engine's turbine temp (T6 or EGT) was ok and then we let go that prop, trsut me mate ... Don't try to catch it back after that first turn, for I believe "Twin Otter's" PT6 engine have a reduction gear ratio somewhere around 5:1. This shows how much rotation is important to have torque. So, your torque wrench would have the same effect, for you would read very little torque if there is no rotation. But once that wheel is spinning, that's another story.

This is also why helicopters have a torque indicator in the dash ... If you drop gearbox speed to low, you will then loose torque and run into a risk of stalling that main rotor.
if the housing is free to rotate a small angle
Yes ... It is free to rotate and you can put it at the angle you want over 360°.
(though you probably already have a torque transducer, don't you?)
Nope ... Something we have to get down the road.
Personally, I'd want to know that before spending any time at all on a gearbox
True ... We will do this one step at the time and we will sure try to get as much data as we can before going into finding and getting a gearbox. This makes me think ... Would'nt you like to be next to me at this time Mike ???? ... he he he :lol:

As for having a glimps of what torque we have right now, I am using a computer program called "Engineering Power Tools" http://www.pwr-tools.com/ which has a "Torque and Power" calculator that can give me this info, given we provide adequate data to it. You should have a look at this software ... It is full of good and useful stuff in it.

Anyway Mike ... I hear you loud and clear Budy ... I am just going one step at the time but will give your advices the highest consideration ... Trust me on this one :wink:

I will keep you posted,

Thanks and regards,
Luc
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Re: Pressure Gain Combustion (Now Proven)

Post by luc » Thu Aug 14, 2008 1:27 pm

Eric wrote:If you have a specalist that acts like breaking a turbine rpm record is a good thing, it might be a good time to get a new specalist.
Eric,

The goal here is not to break something, but more to establish limits and gather data. And no I won't change specialist for this guy was able to select the right turbo model just by looking at a simple video. Who esle can claim such experience for this guy is a turbo "Pro".

Remember this, there is no common sens designing something that will have its "Normal Operation Conditions" to close to its upper boundry limits, for this usually leads to hearly stage operation failures and which is to often seen these days.

There are to goals to do this for us;

1) To see where "No man Lands" is so we stay away from it,
2) Establish optimum "Engine power to Speed gain" point so we won't build something that burns fuel for nothing or miss out on that optimum operation point.

Hope this clarifys,

Regards,
Luc
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Re: Pressure Gain Combustion (Now Proven)

Post by Mike Everman » Thu Aug 14, 2008 4:09 pm

luc wrote:This is where you are wrong budy. In such application, "Speed or RPMs" are crutial to get torque. Let me put it this way ... Years ago up north during extreme winter cold conditions, we use to help turboprops to start by holding the prop in our hand so the power turbines would not turn so the engine's temp would rise rapidely. It was really easy to hold that prop since nothing was turning, but once the engine's turbine temp (T6 or EGT) was ok and then we let go that prop, trsut me mate ... Don't try to catch it back after that first turn, for I believe "Twin Otter's" PT6 engine have a reduction gear ratio somewhere around 5:1. This shows how much rotation is important to have torque. So, your torque wrench would have the same effect, for you would read very little torque if there is no rotation. But once that wheel is spinning, that's another story.
Luc, yeah I would love to be there! I'm going to some point north of Toronto in Sept, but alas, just for fishing and drinking with crazy canucks.

You're not getting my point about the "poor man's dynamometer", let me explain.
The main point you've missed from my post is that the torque measurement is not of the turbine shaft. That spins freely. You're right in that torque at zero rpm is meaningless. The torque you sense is the reaction torque at the housing due to the compressor pumping air. This has a 1:1 correlation to torque output of the turbo at some rpm.
The gate valve (variable restrictor) on the output of the compressor allows you to adjust the reaction torque so it pulls the RPM down to a number you want data for.

Setup:
The turbo/compressor housing must be on a bearing so it can rotate freely, and the PJ oriented up or down as you have it.
The torque gage is attached to the housing and senses torque with respect to ground.
You can place this bearing and torque gage anywhere, actually, ideally at the CG of the whole system, but axis parallel to the turbo rotational axis. Torque is torque, no matter where it is applied or read. At a guess, this point would be somewhere on the PJ exhaust pipe, but you can add balance mass anywhere to put this axis wherever is practical.

Procedure:
Get the PJ running at some known throttle level.
Adjust the gate valve on the compressor output until the rpm drops to some value, like 40,000.
Record torque and rpm.
Adjust gate valve for 30,000 rpm, record torque.
Etc;;
Change PJ throttle level and repeat.

You will find a power curve for the system, but more importantly, you'll find the optimum relationship between PJ throttle and the peak of the power curve. If the curve flattens out before full throttle, time for a larger diameter turbo.

All this must be known before you can design/spec a gearbox, and this (50KRPM+ input side) gearbox is not trivial, as you may know. You can waste many dollars on it when this testing is simple and fun!
Mike
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Re: Pressure Gain Combustion (Now Proven)

Post by luc » Thu Aug 14, 2008 4:37 pm

Mike Everman wrote:
luc wrote:This is where you are wrong budy. In such application, "Speed or RPMs" are crutial to get torque. Let me put it this way ... Years ago up north during extreme winter cold conditions, we use to help turboprops to start by holding the prop in our hand so the power turbines would not turn so the engine's temp would rise rapidely. It was really easy to hold that prop since nothing was turning, but once the engine's turbine temp (T6 or EGT) was ok and then we let go that prop, trsut me mate ... Don't try to catch it back after that first turn, for I believe "Twin Otter's" PT6 engine have a reduction gear ratio somewhere around 5:1. This shows how much rotation is important to have torque. So, your torque wrench would have the same effect, for you would read very little torque if there is no rotation. But once that wheel is spinning, that's another story.
Luc, yeah I would love to be there! I'm going to some point north of Toronto in Sept, but alas, just for fishing and drinking with crazy canucks.

You're not getting my point about the "poor man's dynamometer", let me explain.
The main point you've missed from my post is that the torque measurement is not of the turbine shaft. That spins freely. You're right in that torque at zero rpm is meaningless. The torque you sense is the reaction torque at the housing due to the compressor pumping air. This has a 1:1 correlation to torque output of the turbo at some rpm.
The gate valve (variable restrictor) on the output of the compressor allows you to adjust the reaction torque so it pulls the RPM down to a number you want data for.

Setup:
The turbo/compressor housing must be on a bearing so it can rotate freely, and the PJ oriented up or down as you have it.
The torque gage is attached to the housing and senses torque with respect to ground.
You can place this bearing and torque gage anywhere, actually, ideally at the CG of the whole system, but axis parallel to the turbo rotational axis. Torque is torque, no matter where it is applied or read. At a guess, this point would be somewhere on the PJ exhaust pipe, but you can add balance mass anywhere to put this axis wherever is practical.

Procedure:
Get the PJ running at some known throttle level.
Adjust the gate valve on the compressor output until the rpm drops to some value, like 40,000.
Record torque and rpm.
Adjust gate valve for 30,000 rpm, record torque.
Etc;;
Change PJ throttle level and repeat.

You will find a power curve for the system, but more importantly, you'll find the optimum relationship between PJ throttle and the peak of the power curve. If the curve flattens out before full throttle, time for a larger diameter turbo.

All this must be known before you can design/spec a gearbox, and this (50KRPM+ input side) gearbox is not trivial, as you may know. You can waste many dollars on it when this testing is simple and fun!
Okey Mike ... Got you now and indeed, I did not understand you correctly at first.

Now ... One problem. Both the turbos I have here don't have turbine and compressor housings mounted on bearings, but they are attached to the bearing housing by means of "V" clamps for the big turbo and "Squeeze" clamps for the small one. This said, yes I can turn these housings if I loose-up these clamps, but rotation is done face to face between housing which represent a big friction factor, not saying that if I lossen these clamps, I might run into a scenario that either housing will get out of alignement and get in contact with the rotating compressor.

Here are some pictures so you see what I mean.

Anyway ... Got the picture now and understand what you mean.

Regards,
Attachments
Small one (Turbine).JPG
Small one (Compressor).JPG
Big one (Turbine).JPG
Big one (Compressor).JPG
Luc
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Re: Pressure Gain Combustion (Now Proven)

Post by Mike Everman » Thu Aug 14, 2008 5:02 pm

Cool, thanks for the pics. You don't need to mess with any of that. As I said:
"You can place this bearing and torque gage anywhere, actually, ideally at the CG of the whole system, but axis parallel to the turbo rotational axis. Torque is torque, no matter where it is applied or read. At a guess, this point would be somewhere on the PJ exhaust pipe, but you can add balance mass anywhere to put this axis wherever is practical."

This is strange, but true! You don't even need to be very much on the CG, as the angle it goes through to make a torque measurement is very small, so once you've zeroed the gage, gravity effects of the imbalance will be tiny.

I imagine it a simple matter of welding a shaft on your PJ exhaust tube, coming out parallel to the turbo axis, with its centerline roughly intersecting the CG of the whole assembly. The bearings on the shaft then become the mount for the whole assembly. If you were to unhook all the utilities, you would be able to turn the whole setup freely. Then you put your torque gage on the end of the shaft, with the other end of the gage secured to the bench. If using a dial torque gage, then just put a socket on it, have a hex bolt head protruding from the end of the shaft, and let the handle just hit the table.
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Re: Pressure Gain Combustion (Now Proven)

Post by luc » Thu Aug 14, 2008 6:21 pm

Hi again Mike,

Yaa ... Okey ... Got you.

Knowing the entire assembly is attached to my home made support squeezed between the turbine inlet flange and PJ adapter, I guess the only thing that I need to do at this point is to add a paralel axis shaft to this support and have everything hanging. Then, position the torque sensor anywhere it would be best suited.

Anyway ... Got your picture mate and I find it very appropriate and low cost indeed.

I will complete what I am doing now, which is basically run the bigger setup, after which, I will proceed with your "ME Torque meter" ... He he he :lol: "ME" standing for Mike Everman torque meter :lol:

But Heyyy .... I am the first to always claim "Stay off complicated solution". So why not this time too. This torque meter is way off what I saw in the pass testing real gas turbine, but who cares ... As long as it works ... That's perfect.

Very good thinking Mike ... Thanks.

By the way ... I will really get pissed OFF ... If I hear you were in Canada and especially as close as Toronto ... And you did not come to see me in Lac St-Jean. Try to add or keep a day or two to drop by, for I also have a few lakes were you can see and catch few 5 pounder trouths. Caugh 15 last weekend and missed these big trouths 3 times and where one of them broke my fly fishing rod ... Yeap ... You read it right ... Broke my fishing rod.

You will go crasy if I can bring you to my "Magic Lake" for if you bend over the canoo side, you can see those big mother ****** swiming right under the boat.

Taught (Now he is going NUTS ... He he he :lol: )

Regards,
Luc
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Re: Pressure Gain Combustion (Now Proven)

Post by luc » Thu Aug 14, 2008 8:18 pm

Mike Everman wrote:I expect it won't be as easy when the turbo represents more impedance to the motor
Hi Mike,

Remember the above sentence of your ??? Well ... I am in it up to my hears now ... :? :(

I am trying to have the bigger setup running but the only thing I get are Piff2 ... Paff ... Pouff ... BANG he he he :lol:

I guess you got this one right when you said "I expect it won't be as easy when the turbo represents more impedance to the motor". Did you really had to say it you bad bird ... he he he ... :lol: :?

I tried changing the tail pipes lengt to have all the combustion before the turbo ... But no changes. I will try something tomorow and keep you posted.

Loke I said ... You can't have a mouse swalow a steak ... :lol:

Regards,
Luc
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Re: Pressure Gain Combustion (Now Proven)

Post by Mike Everman » Thu Aug 14, 2008 8:56 pm

I'm thinking you need an electric starter motor to spin up the turbo until your PJ can take over...
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Re: Pressure Gain Combustion (Now Proven)

Post by luc » Fri Aug 15, 2008 12:46 pm

Mike Everman wrote:I'm thinking you need an electric starter motor to spin up the turbo until your PJ can take over...
Hi Mike,

Na ... na ... na ... Noway Mike ... He he he :lol:

All this effort is exactly .... To stary away from starters and batteries.

Thanks for the advice ... But I have more other options :arrow: :idea: before considering starters and if indeed, it boils down to having a starter, we will simply drop this project :? .

But like I said ... I still have many other options up my sleeve ... :idea: :twisted:

Thanks anyway,
Luc
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Re: Pressure Gain Combustion (Now Proven)

Post by Jonny69 » Wed Aug 20, 2008 4:25 pm

Good effort Luc. Just a crappy picture but here's the one I built for my degree:

Image

I didn't get a chance to measure any rpm's but it ran pretty fast and glowed up like yours!

I'll buy you a beer, we can toast to everyone who says it can't be done!

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Re: Pressure Gain Combustion (Now Proven)

Post by Mike Everman » Wed Aug 20, 2008 5:24 pm

Hey Jonny, long time no hear!
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Re: Pressure Gain Combustion (Now Proven)

Post by Jonny69 » Thu Aug 21, 2008 5:58 pm

Hi Mike, yup, long time no see! Good to see you all still on here!
luc wrote:
Mike Everman wrote:I expect it won't be as easy when the turbo represents more impedance to the motor
Hi Mike,

Remember the above sentence of your ??? Well ... I am in it up to my hears now ... :? :(

I am trying to have the bigger setup running but the only thing I get are Piff2 ... Paff ... Pouff ... BANG he he he :lol:

I guess you got this one right when you said "I expect it won't be as easy when the turbo represents more impedance to the motor". Did you really had to say it you bad bird ... he he he ... :lol: :?

I tried changing the tail pipes lengt to have all the combustion before the turbo ... But no changes. I will try something tomorow and keep you posted.

Loke I said ... You can't have a mouse swalow a steak ... :lol:

Regards,
So Luc, I don't know if your engine is valved or valveless. Mine has valves and you can block it up quite significantly and it will still start and run. It'll even run with the turbine mounted on off-the-shelf ball bearings packed with thick grease, though it won't spool up very well like this. Switch to the valveless head and suddenly it's very sensitive to having the exhaust covered in any way.

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Re: Pressure Gain Combustion (Now Proven)

Post by Mike Everman » Thu Aug 21, 2008 6:09 pm

Hey, Jonny,
Luc's is a pressure jet.
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Re: Pressure Gain Combustion (Now Proven)

Post by luc » Thu Aug 21, 2008 7:18 pm

Mike Everman wrote:Hey, Jonny,
Luc's is a pressure jet.
Nope Mike ... It's a PulseRam ... He he he :lol:

Joking .... It's a PulseRam pressure jet ... :lol:

So ... You coming fishing soon Mike????

Cya,
Luc
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