Impeller

[revndave]

Got my impeller back.11lbs. I like very much :D
http://www.***boat.com/image_center/data/500/686100_0220.JPG
http://www.***boat.com/image_center/data/500/686100_0226.JPG
http://www.***boat.com/image_center/data/500/686100_0224.JPG
http://www.***boat.com/image_center/data/500/686100_0228.JPG

[Johnwithjm]

Nice Dave :D

[Hustler]

Hey Dave, is that the mag bronze from aggressor? who detailed it for you? Tommy?

[revndave]

Hey Dave, is that the mag bronze from aggressor? who detailed it for you? Tommy?
All of the above

[Hustler]

How much did it weigh before? I know mine is heavy but have no idea what it weighs.

[revndave]

It weighted about 14lbs.

[sdpm]

Be careful ! Keep a close eye on it!

[HammerDown]

:idea: It appears someone cut grooves in the wear ring area of the Impeller...I had thought this was a no-no. also I belive in the Seloc Jet drive book it also states, this should not be done. :confused:

[miller19j]

:idea: It appears someone cut grooves in the wear ring area of the Impeller...I had thought this was a no-no. also I belive in the Seloc Jet drive book it also states, this should not be done. :confused:
I was just thinking the same thing. What's the scoop on the grooves?

[Cs19]

Be careful ! Keep a close eye on it!
Why do you say that SDPM ?

[flat broke]

I'm gonna go out on a limb and say because Dave is running upwards of 1000hp and the mag bronze ain't bulletproof :) Maybe that or the fact that a drop in weight from 14lbs to 11lbs is a 20% reduction in material...
Hopefully it hauls ass for ya Dave!!!! When you going over to the ski cove and simulating a little 1/4 mile action? ;)
Chris

[Huffer]

Looks Just Like Mine!20 Years Old,mine Still Looks Great.my Bowl
Was Detailed The Same!makes A Very Big Difference!

[revndave]

Wear ring grooves create a hydraulic seal.Boats is running good.Trying out different nozzle inserts.So far it likes more nozzle dia.3.065 :yuk: 3.090 :) 3.125 :confused:

[Heatseeker]

:idea: It appears someone cut grooves in the wear ring area of the Impeller...I had thought this was a no-no. also I belive in the Seloc Jet drive book it also states, this should not be done. :confused:
The B-C stainless I got with my boat had the same grooves. From what I was able to find out, some old school pump guys added the grooves and tightened the wear ring clearance a bit.

[sdpm]

Why do you say that SDPM ?
Hi CS, like Flat Broke said. Mag/Bronze is not all that strong. Removing that much material is not going to help! I've seen quite afew "Mag/Bronze impellers come apart or atleast crack after just a few runs. So my advice is to just keep an eye on it and check it often. He has a fairly heavy boat (21' Daytona) with a stout engine. All the more reason. We checked our s.s. impeller after every race. Cheap insurance. Thats all. Nothing negitive. Hopefully none taken.

[Cs19]

None taken, I only wanted to hear your thoughts on it,and I agree with everything you mentioned.
I run a stainless as well, breaking it is the least of my worries at this point, but I do check it after every race or river trip.
Hope all is well, see you in about a month :220v:

[Fogged Gullwing]

I Thought that Mag Bronze was good to 4000 HP? That is what they advertise!!! So what problems have been found? I'm going to put a thousand HP to mine Help!!!!! Jack detailed mine after I got it.
BK

[revndave]

Tom has run mag bronze in Blue Thunder with no problems.2000+hp

[OkieDave]

Even a good SS impellor can break. I ran over a roller at full throttle one time and the pump got a gulp of air and laid one blade over on the front side of the impellor. it was an easy fix but if I'd kept running it, it could have gotten worse. Good thing about SS, it welds nice. :D

[bp]

there's stainless, and then there's stainless. 304 can deform after years of heavy use, and eventually fail. need to keep an eye on it.
current mag bronze impellers are extremely strong, but as stated, you should keep an eye on those as well. don't assume that all these well known blown boats have no problems with their impellers, just because you may not have read about it in ***boat. stuff happens. if people have had no problems, they'll say so. sometimes, they won't say anything.

[Mr.&Mrs.Budlight]

I had an orginal berkley ss impeller that Scotten blueprinted, that was cracking in multiple places. Scotten said it was a porest casting. Better keep an eye on it!!! Budlight

[pops1]

Hi CS, like Flat Broke said. Mag/Bronze is not all that strong. Removing that much material is not going to help! I've seen quite afew "Mag/Bronze impellers come apart or atleast crack after just a few runs. So my advice is to just keep an eye on it and check it often. He has a fairly heavy boat (21' Daytona) with a stout engine. All the more reason. We checked our s.s. impeller after every race. Cheap insurance. Thats all. Nothing negitive. Hopefully none taken.
I WOULD DIFFER WITH YOU ON OUR Mag Alloy. It charts out @ 110,000+PSI tensile, which exceeds most S/Steel Impellers made. All our Mags have very heavy side walls and shrouds to insure a better cast. You can pull several pounds out by trimming the side shrouds(Blue Printing). Our Mag Alloy has been a 9 year extensive development to arrive at the exact alloy combination we now use. As a comparison last year we made a total of 23 S/Steel Impellers vs several hundred Mags. Our S/Steel is 17-4 Mild H/Treated and charts out @ 135,000 tensile. Its the same alloy we use for our Race Shafts. In almost every case its gone into fuel boats or just hard core S.S. fans that do not believe. The Memory on our mag is as good or better than S/S. and the year after year re-usage of the same mag proves it. FYI

[toad polumsky]

Hey pops,
Can bronze impellers be repaired? I know that ss impellers can be welded. Maybe that is why some people prefer ss over bronze. Why buy an expensive impeller that can not be fixed when you can buy a stainless for a couple hundred more bucks and use it forever.

[Wild Bill]

What about resistance to cav burns? Are the SS and mag b equal in that regard?

[Danhercules]

:idea: It appears someone cut grooves in the wear ring area of the Impeller...I had thought this was a no-no. also I belive in the Seloc Jet drive book it also states, this should not be done. :confused:
I have those on mine. They were there when I took my impeller to MPD to get turned down to a "B". He told me, (if I remeber right) its was an "old school" trick. I asked if it was bad, he said it will not hurt, but the one problem is sand can get trapped in the grooves and cause premature wear.
Nice piece Dave, looks like an "OUT OF THE BOX" Aggressor to me!! :crossx: :rollside: :p

[pops1]

Hey pops,
Can bronze impellers be repaired? I know that ss impellers can be welded. Maybe that is why some people prefer ss over bronze. Why buy an expensive impeller that can not be fixed when you can buy a stainless for a couple hundred more bucks and use it forever.yES MAG IS WELDED BY GOOD WELDERS ALL THE TIME. Specify Mag when getting rod. it makes a diff. Frontal fatigue happens with HP and big bites over time on Mag or S.S. both can be welded. Mag like S.S. takes a good heat. Its when you try to detail Mag that you gain respect for the alloy. Its Tough Stuff!

[pops1]

What about resistance to cav burns? Are the SS and mag b equal in that regard?I have yet to see Cav burns on a Mag. But like someone in prior said + If you have burns you are not loading hard or someone did a bad flow design to cause the burn. If not loading find out why!
You are leaving performance behind.

[pops1]

I have those on mine. They were there when I took my impeller to MPD to get turned down to a "B". He told me, (if I remeber right) its was an "old school" trick. I asked if it was bad, he said it will not hurt, but the one problem is sand can get trapped in the grooves and cause premature wear.
Nice piece Dave, looks like an "OUT OF THE BOX" Aggressor to me!! :crossx: :rollside: :p In Deep weel pumps and others, Threaded Grooves was thought to cause a wash bearer. As water bypassed the wear ring it would run into these pressure locks caused by the grooves.
The right way to do these is to reverse thread the grooves- So there is a reverse pressure created at the bypass point. In all with today motors and pump parts, I think you could run 50 passes on each- with or with out and never see a time change or mph change (Excluding Driver, Air etc.) But thy sure look good and make you ask why!.

[revndave]

Pops 1 thanks for all the info.

[toad polumsky]

Originally Posted by Danhercules
I have those on mine. They were there when I took my impeller to MPD to get turned down to a "B". He told me, (if I remeber right) its was an "old school" trick. I asked if it was bad, he said it will not hurt, but the one problem is sand can get trapped in the grooves and cause premature wear.
Labyrinth Seals
The Labyrinth Seal is an effective barrier against water and other contaminants that destroy bearings. Non-contacting rotary and stationary elements provide a restricted flow path and utilize centrifugal force and gravity to prevent intrusion of contaminants into the bearing chamber. Unlike common lip seals, the Labyrinth Seal will not damage shafts and has a virtually unlimited life.
http://powmat.com/brush.html

[pops1]

Originally Posted by Danhercules
I have those on mine. They were there when I took my impeller to MPD to get turned down to a "B". He told me, (if I remeber right) its was an "old school" trick. I asked if it was bad, he said it will not hurt, but the one problem is sand can get trapped in the grooves and cause premature wear.
Labyrinth Seals
The Labyrinth Seal is an effective barrier against water and other contaminants that destroy bearings. Non-contacting rotary and stationary elements provide a restricted flow path and utilize centrifugal force and gravity to prevent intrusion of contaminants into the bearing chamber. Unlike common lip seals, the Labyrinth Seal will not damage shafts and has a virtually unlimited life.
http://powmat.com/brush.htmlIs that what a Reverse thread is.!

[toad polumsky]

No that is what the grooves in the skirt of the impeller are trying to achieve. Check out the second diagram in this link.http://www.powmat.com/brush.html

[LVjetboy]

"No that is what the grooves in the skirt of the impeller are trying to achieve. Check out the second diagram in this link"
I posted about Labyrinth seals earlier in this thread (2/10) but my post was removed...Hammer said he didn't know why...supposed computer glictch. Since Labyrinth seals were mentioned again in a later post, I'll post again.
I've seen the application in turbine engines and I've heard and read what Danherc refers to. Seloc says (p7-8), "From an unreliable, unknown source, an undocumented and unsubstantiated theory quietly finds its way into marine shops around the country. (my note: lots of "un" this and that drama don't you think) The practice of cutting a series of grooves around the outer diameter of the impeller collar is not uncommon but never the less prevails. The premise seems to be: water finding its way into these grooves will "seal" around the impeller and act as an O-ring. (my note: Although the labyrinth enhances a fluid pressure drop thus sealing efficiency, I don't think it compares to an O-ring)
Seloc goes on to say, "Nothing further from the truth could be possible. Such grooves will NOT produce a "seal", will NOT maintain pump efficiency, but will actually produce exactly the most unwanted results." (my note: Whoever wrote Seloc failed an effective writing course. And Seloc's been wrong in the past. That aside, how did the writer verify grooves will not produce a better seal?)
Seloc goes on to say, "The grooves will allow more "dead water" to flow around the impeller causing slippage, cavitation, and turbulence. All determent to efficiency." (my note: How was that measured?)
Seloc continues with, "the increase in clearance between the impeller and the wear ring allows small pebbles or grains of sand to wedge between the two surfaces and cause considerable damage."
Now I don't claim the rounded grooves shown in Revndaves picture are a true Labyrinth or as effective. But I'm thinking the idea of a Labyrinth seal may work and Selocs put-down seems a bit weak in proof.
Also, as I said in my earlier post that was mysteriously removed, I'd like to see a spiral reverse pumping design. Not sure if that's what Pops refered to but maybe.
jer

[HammerDown]

"No that is what the grooves in the skirt of the impeller are trying to achieve. Check out the second diagram in this link"
I posted about Labyrinth seals earlier in this thread (2/10) but my post was removed...Hammer said he didn't know why...supposed computer glictch.
Also, as I said in my earlier post that was mysteriously removed,
jer
Trust this...I never touched that post. Some strange things have been happening around here (not that Im not one of them) :D

[toad polumsky]

As you can see from the diagram, the labyrinth teeth must fit down in the corresponding grooves on the skirt. So this type seal will not work because the wear ring would not slip on the impeller. Unless the wear ring was split.http://www.powmat.com/brush.html

[Duane HTP]

Okay guys, here goes. The Labyrinth seal DOES in fact work when it is set up correctly. However, cutting grooves in an impeller wear ring surface is NOT setting up the seal properly. It can not be done very successfully with a metal wear ring. It CAN be done with the ULTIMATE WEAR RING though. The trick is, DO NOT cut grooves in the impeller. Instead, turn down the wear ring surface of the impeller .030" all except for two or three ridges about .060" wide. Then install an Ultimate Wear Ring that is an interference fit to the ridges. Put the boat in the water and fire it up and shut it off several times. Then take it out and run it slowly for a while. Gradually take it up in RPM each time until you have reached full WOT. By the time you have done this, the ridges on the impeller wear ring surface will have formed grooves in the Ultimate Wear Ring surface. When you put the big HP to a pump like this, the impeller expands, the ridges on the impeller surface spread into the groves on the wear ring and presto, You have a Labyrinth Seal that hole shots like a m((&*^&. Do not try this with a metal wear ring, it will wipe it out. By setting up a pump this way, you can have an excellent seal on the pump that demands NO HP from your motor. I've run wear rings like this on 3000 hp set ups with as much wear ring side clearence as .080" and still had a very well sealed pump. I wish I knew how to run a CAD program to make a good diagram.

[steelcomp]

Okay guys, here goes. The Labyrinth seal DOES in fact work when it is set up correctly. However, cutting grooves in an impeller wear ring surface is NOT setting up the seal properly. It can not be done very successfully with a metal wear ring. It CAN be done with the ULTIMATE WEAR RING though. The trick is, DO NOT cut grooves in the impeller. Instead, turn down the wear ring surface of the impeller .030" all except for two or three ridges about .060" wide. Then install an Ultimate Wear Ring that is an interference fit to the ridges. Put the boat in the water and fire it up and shut it off several times. Then take it out and run it slowly for a while. Gradually take it up in RPM each time until you have reached full WOT. By the time you have done this, the ridges on the impeller wear ring surface will have formed grooves in the Ultimate Wear Ring surface. When you put the big HP to a pump like this, the impeller expands, the ridges on the impeller surface spread into the groves on the wear ring and presto, You have a Labyrinth Seal that hole shots like a m((&*^&. Do not try this with a metal wear ring, it will wipe it out. By setting up a pump this way, you can have an excellent seal on the pump that demands NO HP from your motor. I've run wear rings like this on 3000 hp set ups with as much wear ring side clearence as .080" and still had a very well sealed pump. I wish I knew how to run a CAD program to make a good diagram.
How on earth do you have .080" side clearance and still get the impeller to make the grooves in the "ultimate" wear ring???? Impellers don't grow .080"! I'm thinking maybe .005-,010", maybe worst case .020". :idea:

[Duane HTP]

Then install an Ultimate Wear Ring that is an interference fit to the ridges
In other words NOT a standard wear ring size, one that rubs, (interference fit), on the grooves of the wear ring.
That was an extreme example, but it works. The ridges were .080" tall. Re-read the sentence above and you will underderstand. Normally, I would use a .030" ridge with an Ultimate Wear Ring that is .020" to .025" undersize. Thus, INTERFERENCE fit. Your ridges will fit the grooves very closely and you will still have a .020" to .025" clearance on the rest of the wear ring. Does that help explain it?

[steelcomp]

No.
Regardless of the depth of the groove, the wear ring has to be able to slip over the impeller, even with interfearance on the high point of the ridges. So where the wear ring is making contact with the ridges, there is zero clearance. The wear ring can't be any smaller than the largest dia. of the impeller wear ring surface, (tops of the ridges) no matter how deep the grooves. Right? The only thing that actually makes a groove in the wear ring is the spinning and expansion of the impeller, which if it grows .020, means there is a .020 deep groove in the wear ring from the .06 +/- wide ridge(s) on the impeller. Right? So what does it matter how deep the groove in the impeller is as long as it's deeper than the amount the impeller will expand??

[Duane HTP]

Give me a call tomorrow.
So what does it matter how deep the groove in the impeller
You're not reading this right, there is NO groove in the impeller, that's the point I'm trying to make. It Doesn't work that way. There's a lot more involved here than you are seeing. Okay. In a perfect world you would be close. This is not a perfect world. The shaft and the impeller both flex some. You have not taken that into consideration. One other thing, your metal wear ring will not give, I agree. But for assembly purposes ours will. 316-794-8616

[pops1]

Originally Posted by Danhercules
but the one problem is sand can get trapped in the grooves and cause premature wear.
http://powmat.com/brush.htmlI agree, I just received a Impeller in to re detail and balance with the groves. It became a sand block.

[pops1]

Give me a call tomorrow.
You're not reading this right, there is NO groove in the impeller
I am sure what he is saying here, is he sets it up for a burn in. You can do that with his wear ring. Remember its all about application. If you are pure Drag Boating, maybe, Yet I still say look @ the ticket - you will not see any
change. So why cut up a good Impeller!

[Duane HTP]

I agree with look at the ticket. But there are many things that we do to a pump that are pretty hard to define by the ticket. Yet when all is said and done, I'l bet the guy who wins the eight second class has 99 per cent of it in his pump on Sunday. Like it's the right total combination that wins.

[LVjetboy]

"As you can see from the diagram, the labyrinth teeth must fit down in the corresponding grooves on the skirt. So this type seal will not work because the wear ring would not slip on the impeller. Unless the wear ring was split"
I've seen both straight, stepped and varied labyrinth seal tooth designs. A labyrinth seal can be done without gooves on the skirt (wear ring)...here's a picture:
http://members.cox.net/lvjetboy/LabDesign.jpg
I'm still interested in the spiral design. Has anyone tried it for our application?
jer

[Duane HTP]

Yes, I have used it before. But, I was using it with a little different idea in mind. We turned the spiral to make the groves pull the sand and trash away from the corner of the liped wear ring. Does it work?? I think so, but I doubt that the "ticket" will tell you anything.

[pops1]

Yes, I have used it before. But, I was using it with a little different idea in mind. We turned the spiral to make the groves pull the sand and trash away from the corner of the liped wear ring. Does it work?? I think so, but I doubt that the "ticket" will tell you anything.
Now it all comes out. That Guy that has 95% of all the good stuff, is the guy that wins. "AMEN" - Yet you know, I had 4 Racers in here this year, that told me the reason they were beat- WAS LUCK! So this year - We are going to bottle LUCK in a Salt Shaker with a candle and a book of matches. and just watch the outcome.
Some of the fastest guys out there will get this major go PEE or #2 need & Red Light.
Some will just fall asleep on the rope.
Some will not turn on the fuel.
Some will see a Wagon full of Beer with Naked Dancers on top Dancing & miss the ramp call.
Yes it will become "VOODOO" Racing at its best!. Marketing will be done by the GUY's with the Flatties Like "Jet Boat GURU" Tony! assisted by the Pet Rock Foundation and Pet Rock Relationship Assoc.
Propers have been looking for something like this for Years. It puts the slower boats to final rounds and now gives them a 40% chance at winning. :eat:

[Duane HTP]

Hey Pop's we were talking boat performance here, not driver error. I agree with you again 100% on the driver though. I've thought seriously about putting a driver in the seat and controlling the boat by radio control. HA HA!
Maybe we could eliminate the driver error. But that wouldn't be much fun for the driver would it? (grin).

[Duane HTP]

By the way, that last batch of Mag/Bronze Impellers I got from you were the Cadillac of impellers. Good Job.

[Old Guy]

Duane,
Does the friction wear away the wear ring to form grooves, or reform the wear ring? Does wear ring material go away or move?
Does the impeller projection have a shape (sawtooth) or is it like a straight step? It seems like it would need to have some kind of relief angle so as to allow assembly.
Once the new seal configuration has been achieved, can the impeller be removed without wrecking the wear ring?
Thanks,
Roger

[Duane HTP]

Does the friction wear away the wear ring to form grooves,
YES, That's why you run it a little at a time at first so as not to heat it up when first assembled.
Does the impeller projection have a shape (sawtooth) or is it like a straight step? It seems like it would need to have some kind of relief angle so as to allow assembly.
It is a straight step. The actual inside diameter of the wear ring is exactly the same, (+ or - .002"), as the outside diameter of the ridges.
Once the new seal configuration has been achieved, can the impeller be removed without wrecking the wear ring?
Yes, it is not a problem.
Lvjet, If I send you a hand drawing, could you make a CAD that people could understand? I think it would help.

[PC Rat]

Lvjet, If I send you a hand drawing, could you make a CAD that people could understand? I think it would help.
Duane,
If LV is unavailable, I can do it for you.
Brian

[steelcomp]

This is really interesting. :sleeping:
What's the real world performance gain from all this? I'm not trying to throw ice water on the concept here, but I can't help but think this isn't much more than a gimmick. Sorry if I just can't grasp the significance of this. If everything else was perfect...it might make a difference, but when is that ever the case?? Better places to spend less money and effort, IMO, but it makes for interesting discussion. NOT.

[LVjetboy]

"Lvjet, If I send you a hand drawing, could you make a CAD that people could understand? I think it would help."
Sure no problem send them. I think visuals help too...as you can tell from my posts :smile:
jer

[LVjetboy]

"What's the real world performance gain from all this? I can't help but think this isn't much more than a gimmick. Sorry if I just can't grasp the significance..."
SteelComp, think brainstorming. "A group problem-solving technique in which members let ideas fly new and creative solutions to a problem without regard to (or being inhibited by the perception of) their initial worth." (my edit)
If from a race perspective you're thinking what's a quick and cheap x mph improvement? Then no, this thread is not for you. After all, some seal designs would require extensive impeller machining if not a change in wear ring or pump design.
If from a design perspective you're thinking what new idea can improve jet pump performance and efficiency by better sealing the impeller? Then read on...but only if you're interested. :confused:
Unless of course you've already decided current jet pump impeller seal design can't be improved? In that case please enlighten us as to how you know this.
Are you familiar with how far jet engine technology has come in efficiency and performance based on airfoil design, sealing improvements and secondary flow technology? Small improvements in all aspects eventually add up to x mph. But if you're looking for the whole x mph from one design change then maybe you're looking in the wrong thread. If so then keep on :sleeping: and skip on by...nothing to see here.
jer

[steelcomp]

All Im saying is there are enough places and things to improve on 99% of the boats out there that this seems miniscule AFA performance gain/effort or cost involved. How many guys out there even know if their pump is in straight? When was the last time you checked your valve spring pressures? So you know what your real compression ratio is?? Do you actually have the best cam for your application?? I could go on.
I understain the concepr and agree that it's got it's merit. You're right...every little improvement will add up, and they all count, I just think this one sits pretty low on the list.

[sdpm]

When was the last time you checked your valve spring pressures? So you know what your real compression ratio is?? Do you actually have the best cam for your application??
Question#1- last time I checked all 16 were there!
" #2- ALOT!
" #3- It sounds bitchen so it must be the best!
;) Neil

[pops1]

[i
Are you familiar with how far jet engine technology has come in efficiency and performance based on airfoil design, sealing improvements and secondary flow technology? Small improvements in all aspects eventually add up to x mph. But if you're looking for the whole x mph from one design change then maybe you're looking in the wrong thread. If so then keep on :sleeping: and skip on by...nothing to see here.
jerI will throw this back into the discussion to think about.
Old School was to reverse thread (opp. of rotation)a groove, so the flow on the outside of the wear ring was pushing forward- Not drafting in. The theory
was 2 pressures meeting. SHOW ME THE TICKET!

[MAXIMUS]

I have a few questions for you all to think about. #1 What happens when a pump is a little loose or worn? #2 What happens when the pump is "tightned"? What holds the motor back from reving to the moon? How much nozzle psi a pump makes is dependant on the power applied or not?
Take 2 pumps with identical parts & set one up loose & one tight. What would be the differences with the same hp?

[Duane HTP]

The tighter pump would hole shot better. There is no correct answer to the other question without knowing close to the dyno sheet specs. If the motor ran at it's hp peak with the tight pump it would probably slow down if loosened. If it was running 1000 rpm below it's hp range, it would go faster when loosened up because the motor could make a lot more hp. I've seen a lot of the old Berkeleys come in so loose that they could hardly get a skier up, yet they ran like hell on the top end. Tighten the pump up good, they pull up two skiers easly and slow down. Solution for that scenario; cut the A to a B impeller.

[bp]

[i]Are you familiar with how far jet engine technology has come in efficiency and performance based on airfoil design, sealing improvements and secondary flow technology? Small improvements in all aspects eventually add up to x mph. But if you're looking for the whole x mph from one design change then maybe you're looking in the wrong thread. If so then keep on :sleeping: and skip on by...nothing to see here.
jer
i'm not sure about the whole barrel full of stuff you're talking about here, as i'm sure there is a massive amount of room for improvement in design, as my own personal impeller demonstrates when compared to a stock out of the box one. but getting back to labyrinth seals, they have been used on turbines since christ was standing wheel watches on the ark, and what has been described here is NOT a labyrinth seal. it does sound like a very.. unique way to try and make a gain in the shoulder/wear ring tolerance area. it's just not a labyrinth seal...

[Duane HTP]

Okay bp, we're listening. What is a labyrinth seal?

[bp]

why don't i just try to find a picture of one tomorrow.
generally, each seal half is split, one is installed in the upper case, one in the lower case. both the upper and lower case seals have ports; the upper a steam or water (depending on the turbine section) supply, the lower a drain. the seal is wide, depicted as in the previous drawing, but a picture is better. initially, either water or steam is fed into the seal as the turbine rolled. once up to speed, the seal "seals". there is zero leakage from one "side" of the seal to the other.

[LVjetboy]

"All Im saying is there are enough places and things to improve on 99% of the boats out there that this seems miniscule AFA performance gain/effort or cost involved."
I agree Steel. But then there's other threads talking those issues. To me this's interesting from the pump design perspective...a topic getting little if any attention from mfgs.
"Old School was to reverse thread (opp. of rotation) a groove, so the flow on the outside of the wear ring was pushing forward- Not drafting in. SHOW ME THE TICKET!"
Old School? I missed that. But I have seen recent technical articles on sprial design. As for the ticket...well, that depends on way more than just impeller seal right? :) But I'd be interested in anything you could share on your experience with a spiral labyrinth seal design.
jer

[LVjetboy]

"...and what has been described here is NOT a labyrinth seal. it does sound like a very.. unique way to try and make a gain in the shoulder/wear ring tolerance area. it's just not a labyrinth seal..."
Which post are you talking about bp?
"...once up to speed, the seal "seals". there is zero leakage from one "side" of the seal to the other."
So maybe an adaptive (contact) seal like brush or carbon? To me, labyrinth may be adaptive at break-in but not after wear. Even fan tips against an abraidable outer seal qualify as labyrinth. Some swing both ways. Flexible seals like brush or lip adapt to wear and are most effective with contact. But in the end may become a simple form of labyrinth. To me, except for wear, labyrinth is a non-flexible and non-adjustable seal.
I doubt you'll see brush or carbon technology for our impellers but consider that current wear ring design is just a simple (one tooth) form of labyrinth sealing.
jer

[miketsouth]

gas turbines, specifically the Allison T63 Have been using the interference breakin method for years on their compressor stages.
A plastic like shroud is placed over the first 6 compressor blades and it actually locks the rotor until spun. The blades cut their own tracks in the substance for a very close fit. I think it is called "ablative sealing"
The reverse groove has been around a while too, always "screwing the fluid" backwards trying to decrease the flow.
some of the labyrinth seals i have seen never contact. Just a tortuous route for the fluid to take.
another seal i have seen in steam turbines is a carbon friction seal, similar to the labyrinth seal with spring loaded carbon disks.
I like Duane's solution with the ultimate wear ring and the ablative breakin. Sounds like a very tight seal with a somewhat shortened lifespan.

[Duane HTP]

Life span is not shortened if broke in properly. We ran the same one in
flashback for 5 years. I would not recommend this type of seal for a lake boat that runs a lot of trashy waters. It's probably a waste on anything less than 800 HP anyway. The 800 hp is a guess, not a fact! Jer is drawing up a picture of what I sent him. Be done maybe monday.

[pops1]

[QUOTE=QUOTE]Are you familiar with turbine straightners- which stop the counter rotation air flow. Dave

[miketsouth]

[QUOTE=QUOTE]Are you familiar with turbine straightners- which stop the counter rotation air flow. Dave
no
i have seen straightners though, and what is refered to as "pre-rotation" vanes. Pre-rotation is a loosly used term that describes a device that sits just before the eye of an impeller. I have seen them in water and air systems. It presents the fluid to the eye of the impeller such that the impeller can process it more effectively. Usefull where there is turbulence caused by an elbow or other influences that reduce laminar flow to the inlet. It may be stationary or moveable. When moveable i have seen it used to throttle certain air systems as a capacity modulator.
Mostly air.
I have seen straighteners too. Where i see them is in steam lines just before a flow sensing device. Turbulence will negate any useable pressure measurements without them. I have seen them in pumps too, where there is an elbow close to the inlet..
I am supposing you are talking about the reverse flow caused by vortecies just after the vanes of the turbine. I again suppose the same thing is happening on the outlet of the jet pump impeller and i know it happens after the straightners in the bowl. How much efficiency is lost here i cannot even guess. I suspect that it is part of the suspected smaller cut impeller ineficiency as well as the smaller cut tending toward axial rather than mixed flow.
Duane, when i posted that the lifespan was reduced i knew that these applications were for maximum efficiency, high horsepower stuff. I expected that in a race boat the pump would be torn down or tore up long before the MTBF became an issue. I dont know shit, but it sounds good to me.
It is my understanding that the lipped wear ring and its direction of the water to the eye tended to be an anti cavitation device. Dont know where i heard that but that made sense too. Fits with what i know about low NPSH pumps. They have holes drilled in the eye to let a little head water in to reduce the tendancy to cavitate.
and the labrynth seals that i have seen are not air tight. Just tends to reduce the bypass to an acceptable level.
And i want to try a back cut shoe. You sell them Duane?

[bp]

i have a couple pretty good pics of the bottom case seal installed in the hp section of a turbine that drives a 1200 mw generator. just need lv's email address so he can postem... :rolleyes:

[LVjetboy]

Bp, I pm'd my email.

[LVjetboy]

Ok, here's some drawings illustrating how Duane's Ultimate Wear Ring forms a Labyrinth seal*
The first cross-section view below (Ultimate seal in red) shows how the seal relates to the rotating impeller collar and stationary suction piece shoulder, along with an overview of the pump flow path to help visualize seal placement and function...
http://members.cox.net/lvjetboy/SectionView.jpg
As you can see, the wear ring seals high pressure bowl fluid from leaking towards the intake side. This because bowl pressure will always exceed intake pressure except during shutdown. Side note: Seloc illustration (p. 7-8) explaining excessive impeller-to-wear-ring clearance loss shows the seal leaking the wrong direction along with a questionable seal loss mechanism.
The next view is expanded from above and focuses on the wear ring and impeller collar alone to illustrate the Ultimate Wear Ring seal design...
http://members.cox.net/lvjetboy/WearRing1.jpg
Before break-in, teeth contact the seal and wear. At this point, the seal would be better classified as a contact design such as spring loaded ring or lip with positive contact...not Labyrinth. As the seal wears it tends towards a non-contacting Labyrinth design...
http://members.cox.net/lvjetboy/WearRing2.jpg
Unlike most mechanical contacting seals, an adaptive seal adjusts for minor misalignment yet retains the low friction (non-contact) advantage of the Labyrinth seal. After break-in, you can see the "torturous path" as Mike put it, causing a fluid pressure drop i.e. sealing effect...
http://members.cox.net/lvjetboy/WearRing3.jpg
Each time fluid passes over a sharp corner or around a blockage there will be a pressure drop. Postive contact or NO contact. Labyrinth seals take advantage of this fact without incuring the life and efficiency drawback of a mechanical or positive contact design and related sensitivity to misalignment.
*Illustrations not true to scale. The above is my understanding of seal design and not an endorsement of any product.
jer

[kojac]

After looking at the drawings of how the ultimate wear ring creates a labyrinth seal I can see how it makes perfect sense that performance could be improved.
I wonder how much better performance the hole shot and top speed are compared with the conventional improved blueprinted race pump? Say on a stealth tunnel???
Duane have you compared your wear ring on a supposedly good running boat with no other changes? It would be interesting to see the before and after data?
Really good info.
Kojac

[bottom feeder]

Duane HTP, thank you for sharing your knowledge.
Jer, Thank you for putting this in a form all can understand.

[Squirtin Thunder]

Very Nice Jer !!! Good Job !!!
Ok, here's some drawings illustrating how Duane's Ultimate Wear Ring forms a Labyrinth seal*
The first cross-section view below (Ultimate seal in red) shows how the seal relates to the rotating impeller collar and stationary suction piece shoulder, along with an overview of the pump flow path to help visualize seal placement and function...
http://members.cox.net/lvjetboy/SectionView.jpg
As you can see, the wear ring seals high pressure bowl fluid from leaking towards the intake side. This because bowl pressure will always exceed intake pressure except during shutdown. My note: Seloc illustration (p. 7-8) explaining excessive impeller-to-wear-ring clearance loss shows the seal leaking the wrong direction along with a questionable seal loss mechanism.
The next view is expanded from above and focuses on the wear ring and impeller collar alone to illustrate the Ultimate Wear Ring seal design...
http://members.cox.net/lvjetboy/WearRing1.jpg
Before break-in, teeth contact the seal and wear. At this point, the seal would be better classified as a contact design such as spring loaded ring or lip with positive contact...not Labyrinth. As the seal wears it tends towards a non-contacting Labyrinth design...
http://members.cox.net/lvjetboy/WearRing2.jpg
Unlike most mechanical contacting seals, an adaptive seal adjusts for minor misalignment yet retains the low friction (non-contact) advantage of the Labyrinth seal. After break-in, you can see the "torturous path" as Mike put it, causing a fluid pressure drop i.e. sealing effect...
http://members.cox.net/lvjetboy/WearRing3.jpg
Each time fluid passes over a sharp corner or around a blockage there will be a pressure drop. Postive contact or NO contact. Labyrinth seals take advantage of this fact without incuring the life and efficiency drawback of a mechanical or positive contact design and related sensitivity to misalignment.
*Illustrations not true to scale. The above is my understanding of seal design and not an endorsement of any product.
jer

[pops1]

[QUOTE=miketsouth]no
i have seen straightners though, and what is refered to as "pre-rotation" vanes. Pre-rotation is a loosly used term that describes a device that sits just before the eye of an impeller. I have seen them in water and air systems. It presents the fluid to the eye of the impeller such that the impeller can process it more effectively. Usefull where there is turbulence caused by an elbow or other influences that reduce laminar flow to the inlet. It may be stationary or moveable. When moveable i have seen it used to throttle certain air systems as a capacity modulator.
Mostly air.
I have seen straighteners too. Where i see them is in steam lines just before a flow sensing device. Turbulence will negate any useable pressure measurements without them. I have seen them in pumps too, where there is an elbow close to the inlet..
I am supposing you are talking about the reverse flow caused by vortecies just after the vanes of the turbine. I again suppose the same thing is happening on the outlet of the jet pump impeller and i know it happens after the straightners in the bowl. How much efficiency is lost here i cannot even guess. I suspect that it is part of the suspected smaller cut impeller ineficiency as well as the smaller cut tending toward axial rather than mixed flow.
It is my understanding that the lipped wear ring and its direction of the water to the eye tended to be an anti cavitation device. Dont know where i heard that but that made sense too. Fits with what i know about low NPSH pumps. They have holes drilled in the eye to let a little head water in to reduce the tendancy to cavitate.
QUOTE] Thanks for the response- I did not think of the larger cut Impeller taking on the axial mode -Yet in part I must agree to a minor extent. The biggest exception being "it is still part of a higher pressure system". Axial for all I have seen falls on its face when pressures are introduced and Axial becomes a confused flow line.
I don't see the anti cavatation effect on the Lipped Wear Ring unless that gap that exists betweent the actual wear ring and the suction (caused by the liner would have that effect). What the Lipped portion provides is a very high safety factor to the suction being taken out when a impeller and/or thrust bearing let go.
Would like to E you at a later time regarding water straighteners before and after. We have found great flow rate increases by extending our bowl vanes out ward into the pressure and thrust section (front of the bowl stuffer) and again at the end of our bowls. That same approach was taken with our impeller, providing a longer duration of ride within the encapsulated water section of the Impeller.This has to account for a higher thrust @ release.
I have been working on a new design for a suction for years. Starting with water control at entry and full consideration to high speed. I Hope to provide a working model within the next year in some working form and perhaps get first performance runs.
Again Thank You. Dave

[Duane HTP]

Jer, Thank you for the great illustrations. You did a good job!
Duane have you compared your wear ring on a supposedly good running boat with no other changes? It would be interesting to see the before and after data?
Yes, we have, and the results have been that we were able to release more HP to the pump from the holding rope, quicker. "Hole Shot". I do not feel, however, that our testing was controlled enough to really come up with what everyone wants to call a scientific conclusion. We and many others who set up the wear ring "as per instructions included" like and use it on every pump we build unless the customer requests otherwise.
I also want to say at this time, we don't necessarily recommend this particular configuration of the Ultimate Wear Ring for every boat. They work well without the ridges on the impeller in just about any application.

[pops1]

Jer, Thank you for the great illustrations. You did a good job!
I also want to say at this time, we don't necessarily recommend this particular configuration of the Ultimate Wear Ring for every boat. They work well without the ridges on the impeller in just about any application.
Jer. Thanks for the layout.
Duane, To make all this simple- I still would go with the burn in way you outlined early in this string.

[steelcomp]

What's the wear ring made of??

[Jake W2]

Dude if Duane tells you that he will have to kill you.
Jake ;)

[steelcomp]

Dude if Duane tells you that he will have to kill you.
Jake ;)
Yeah...He'd like you to think that. :rolleyes: