lukenz
Member
Joined: October 2018
Posts: 38
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Post by lukenz on Oct 12, 2018 23:54:32 GMT -5
Hi everyone, First of all, appreciate all the effort of those that take the time to help out on JATO and the generosity of knowledge being shared. I'll cut right to the chase, my build is based on a Garrett turbo re-manufactured for Volvo (Off a truck) and not completely sure on what I have on my hands, all i know is the compressor side is A/R 72, the Garrett P/N is 466076-9019 and Volvo P/N 8112299.   The one interesting characteristic about this turbo is the exhaust turbine inlet is a twin scroll configuration, having purchased the turbo before realization that this can be problematic in the divider being broken down from combustion heat and sending steel particles through the turbine wheel i have attempted to die grind the divider as far down into the inlet as possible (see the below photo).  None the less I will proceed with the build, the turbo dimensions are: Inducer Diameter: 68mm
Outlet Diameter: 91mm
Hub Diameter: 22mm
Based on the above figures the flame tube will be constructed out of 5" stainless tubing (123.4mm ID, 1.8mm wall thickness) and the combustion housing will be constructed out of 6" stainless tube (154mm ID, 2.1mm wall thickness). The end caps and combustion housing to turbine flange will be constructed from stainless plate at 2.1mm thick. Now there are a few specific questions I have (sorry if they have been answered before, tried searching on this forum): 1) How crucial is the distance between the flame tube and the combustion casing wall as the above materials only gives me a clearance of 11.4mm so less than the ideal minimum of 1/2", although only just! Should i add circumference to either stainless tubes to get the perfect volume of FT and combustion housing? 2) Is there an ideal starting distance from the first circumference of primary holes from the inside of the end cap? (end opposite combustion housing outlet) 3) Is there an ideal pattern the different stages of holes should be drilled, and where stage holes require more than one row is there a distance between each row? (inline, staggered etc.) 4) Finally, I have come to understand that the air supply intake should be positioned at the tertiary holes end of the combustion housing, does this mean that the flame tube should be sealed off from the combustion housing except for the primary, secondary and tertiary stage holes, i.e the flame tube is connected (Welded/sealed) to the outlet end cap where it attaches to the turbine flange? Sorry for bombarding you with what may seem OTT questions, but just want to make sure I get this all correct, to minimize the amount of troubleshooting when this engine does not run perfectly during its first startup which we all know will be the case, no doubt there is always things to be ironed out. I will continue to add photo's as I progress, pretty damn excited to get this beast going. Kindest regards, Luke |
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Post by racket on Oct 13, 2018 3:02:28 GMT -5
Hi Luke Just a few things to start off with ............ What is the turbine wheel dimensions and the A/R of its housing , this will provide us with an idea about its match with the compressor . Your flametube to combustor wall gap is a tad tight but should be OK as long as where the air delivery tube attaches to the can you fit a diffusing funnel to provide extra flow area at that critical junction. The end plate that joins the turbo flange needs to be at least 10 mm thick to prevent warpage and leakage under full air pressure and heat. Have you checked Jetspecs for FT wall hole sizes etc ?? Have a look here jetandturbineowners.proboards.com/thread/680/diy-turbines Yes , all the air should go through the flametube wall holes , a "rattly" slipjoint is required for axial expansion of the flametube . And finally , checkout some of the other builds on here for ideas . Keep those questions coming :-) Cheers John |
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lukenz
Member
Joined: October 2018
Posts: 38
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Post by lukenz on Oct 13, 2018 3:19:16 GMT -5
Hi Luke Just a few things to start off with ............ What is the turbine wheel dimensions and the A/R of its housing , this will provide us with an idea about its match with the compressor . Your flametube to combustor wall gap is a tad tight but should be OK as long as where the air delivery tube attaches to the can you fit a diffusing funnel to provide extra flow area at that critical junction. The end plate that joins the turbo flange needs to be at least 10 mm thick to prevent warpage and leakage under full air pressure and heat. Have you checked Jetspecs for FT wall hole sizes etc ?? Have a look here jetandturbineowners.proboards.com/thread/680/diy-turbines Yes , all the air should go through the flametube wall holes , a "rattly" slipjoint is required for axial expansion of the flametube . And finally , checkout some of the other builds on here for ideas . Keep those questions coming :-) Cheers John Hi John, Thanks for the quick reply! Will get the A/R of the turbine housing. For measurement of the turbine wheel, is it just a simple measurement of the overall OD? Could you please explain the diffusing funnel a little further or do you have an example? Yep, I used Jetspecs to work out compressor dimensions and calculate the FT wall hole sizes was just curious on how specific/crucial the placement has to be along and around the FT, i'm probably just over complicating things as I am known to do from time to time lol. Awesome will go with the slip-joint approach which obviously gives the ability to remove the FT as required also. Will spend a bit more time going through the forum looking at other builds, i did a few quick searches but slightly impatient as I have just acquired AutoDesk Inventor and to excited to draw my concept up haha! Thanks again for your kind help! :-) and will get the turbine wheel dimensions and housing A/R when I get back to work. Cheers, Luke |
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Post by racket on Oct 13, 2018 15:28:29 GMT -5
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Post by slittlewing on Oct 14, 2018 12:36:15 GMT -5
Hi Luke,
Look forward to seeing your progress!!
Your turbo is very similar inducer diameter to mine, so hopefully the part of my thread on ft design and hole spacing will help.
I would go for thicker than 2mm on the end caps though if they are flat (my 3mm ones started to balloon at 2 bar on propane where the radial injector made the end cap extremely hot (>900c)
Cheers
Scott
Edit - also I wouldn’t worry too much about the twin scroll, I haven’t had any issues with it yet and mine is same!
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lukenz
Member
Joined: October 2018
Posts: 38
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Post by lukenz on Oct 15, 2018 1:26:58 GMT -5
John, Just watched your video of the jet bike from last decade, crazy the speed you got out of it! Also watched your 9/94 Turbine engine, damn I want to make one after the success of this project! Cheers for the links, fully understand the diffuser concept now, I was thinking that i'll just make it somewhere between the FT & Combustor diameter where it attaches to the combustor wall? I'm fairly damn sure I found the model of turbo, it's a Garrett TA5102 so found online specs which are pretty close to my measurements as follows: Compressor Inducer: 66.9mm Compressor Exducer: 91.0mm Compressor Hub: 22.0 mm Compresor A/R: 0.72 Turbine Inducer: 88.9 mm Turbine Exducer: 77.7 mm Turbine Hub: 26.7mm Turbine A/R: 1.15 Cheers again! Luke |
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lukenz
Member
Joined: October 2018
Posts: 38
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Post by lukenz on Oct 15, 2018 1:35:20 GMT -5
Hi Luke, Look forward to seeing your progress!! Your turbo is very similar inducer diameter to mine, so hopefully the part of my thread on ft design and hole spacing will help. I would go for thicker than 2mm on the end caps though if they are flat (my 3mm ones started to balloon at 2 bar on propane where the radial injector made the end cap extremely hot (>900c) Cheers Scott Edit - also I wouldn’t worry too much about the twin scroll, I haven’t had any issues with it yet and mine is same! Hey Scott! Thanks me too! I did a little more research at work today based on the serial plate and im 99% sure it's a TA5102 and found a New Zealand supplier with the specs I have just posted in response to John, maybe yours is this turbo also, is it a Garrett? Will definitely have a look at your thread, I assume you got yours running well? We're you able to take any measurements of thrust etc? Really!!!  I guess the flat shape is fairly weaker than the cylinder shape of the tube, did you change your end caps out for thicker flat plate? How thick are your FT and combuster tube walls? Good to hear that you have had no trouble with the twin scroll divider, how many hours has your engine done approx.? Cheers, Luke |
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Post by racket on Oct 15, 2018 2:30:50 GMT -5
Hi Luke
The comp and turb dimensions look like a reasonable match so the engine shouldn't have any problems with flows.
With regards thicknesses of combustor and flametubes , 1 mm WT tubing should be OK for you , 120 mm dia flametube inside a 150 mm ID outer can , but flat end caps need to be thick , the turb scroll end needs to be at least 10mm plate , if you use a 7 litre air over water fire extinguisher for the outer can the domed top even though quite thin is safe to several times the pressure you'll produce.
Cheers
John
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lukenz
Member
Joined: October 2018
Posts: 38
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Post by lukenz on Oct 15, 2018 3:03:21 GMT -5
Hi Luke The comp and turb dimensions look like a reasonable match so the engine shouldn't have any problems with flows. With regards thicknesses of combustor and flametubes , 1 mm WT tubing should be OK for you , 120 mm dia flametube inside a 150 mm ID outer can , but flat end caps need to be thick , the turb scroll end needs to be at least 10mm plate , if you use a 7 litre air over water fire extinguisher for the outer can the domed top even though quite thin is safe to several times the pressure you'll produce. Cheers John Hi John, That's good news, thanks for looking at that. I already have the stainless tubing, the 5" has a 1.8mm WT & the 6" has a 2.1mm WT so all legit there. Here is some exact numbers of the stainless tubing I am using; FT tubing has an OD of 127mm, combustor tubing has an ID of 149.8mm leaving me with a 22.8mm difference so an 11.4mm gap between inner and outter tubing. Would you enlarge the outer tube diameter or reduce the FT diameter. My intentions are to run this engine on kero so thinking that having maximum diameters are the goal for it to run well. Re: the end caps I should be using 3mm+ for the cap at the fuel & ignition end? Might pay for me to finish my 3D model of the FT & Combustor and upload it here open for critique on getting it right. Cheers, Luke |
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Post by slittlewing on Oct 15, 2018 3:12:23 GMT -5
John is the expert but I think the advice will be not to skimp on FT diameter and instead keep the 11.4mm gap, it will be enough.
The end caps I would make from 5mm minimum. Mine has a 3mm top cap (now reinforced with ribs) and 5mm baseplate to turbo, but I am using through studs to connect to turbo housing. Probably would have made from 8mm if I was to do it again just for safety.
Highly recommend checking out the threads on here before doing your combustor design as it will save you some iterations of changes!!
Cheers
Scott
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lukenz
Member
Joined: October 2018
Posts: 38
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Post by lukenz on Oct 16, 2018 4:22:05 GMT -5
John is the expert but I think the advice will be not to skimp on FT diameter and instead keep the 11.4mm gap, it will be enough. The end caps I would make from 5mm minimum. Mine has a 3mm top cap (now reinforced with ribs) and 5mm baseplate to turbo, but I am using through studs to connect to turbo housing. Probably would have made from 8mm if I was to do it again just for safety. Highly recommend checking out the threads on here before doing your combustor design as it will save you some iterations of changes!! Cheers Scott Hey Scott, Yes that was my thinking to keep my FT the current size of the 5" tube I have, however I then realized there are two ways to calculate the FT diameter. The slightly more technical way is to calculate inducer area (𝐴=𝜋×𝑟^2), multiply by 3 to get FT area. You then take the FT Area and re-arrange the area of circle equation (√𝑟=𝐴/𝜋 ) making r (radius) the subject to get a FT radius then multiply by 2 to get FT diameter. This method suggests I can use a 116mm diameter FT which I would reduce my 5" (123.4mm) piece of stainless tube therefore increasing the distance between the FT and ID of combustor wall to a 17mm gap!!! I think that will be my best approach. Your right, I will bite the bullet and purchase some 5mm stainless plate (ouch), and I will be using a 10mm base plate to turbo (T3 or T4 Flange?) which I have always done so with turbo vehicles historically. Thanks mate will definitely look at more threads before I finalize how I am going to build mine, less changes the better right, and less money out of my back pocket! Cheers, Luke |
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Post by slittlewing on Oct 16, 2018 5:26:59 GMT -5
Sounds good, I think both would work but the area method is more scientific (and suits your 6" outer tube better). 116mm is close to a 4.5" diameter which you could get "off the shelf" tube for, if you didn't want to laser cut and roll the FT. I used off the shelf 4.5" tube for my reducer (to the turbo) and rolled the FT to sit inside it at the slip joint.
Yeah my first attempt (without the help of this forum) was a bit of a failure so I had to build a new engine from scratch again haha.
Looking forward to seeing the CAD!
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lukenz
Member
Joined: October 2018
Posts: 38
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Post by lukenz on Mar 6, 2019 3:45:15 GMT -5
Sounds good, I think both would work but the area method is more scientific (and suits your 6" outer tube better). 116mm is close to a 4.5" diameter which you could get "off the shelf" tube for, if you didn't want to laser cut and roll the FT. I used off the shelf 4.5" tube for my reducer (to the turbo) and rolled the FT to sit inside it at the slip joint. Yeah my first attempt (without the help of this forum) was a bit of a failure so I had to build a new engine from scratch again haha. Looking forward to seeing the CAD! Finally got around to drawing these CAD drawings, please let me know what you guys think i.e. which will be the most effective? Note: the dotted line in each drawing is where the fuel spray will theoretically hit the combustion chamber wall.    Regards, Luke |
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lukenz
Member
Joined: October 2018
Posts: 38
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Post by lukenz on Mar 10, 2019 6:15:59 GMT -5
Was anyone able to view my ft designs?
Regards,
Luke
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Post by racket on Mar 10, 2019 16:35:36 GMT -5
Hi Luke
Sorry about the delay .
If you intend running on kero maybe replace all those small holes in the two rows of Primary holes with a single row of larger diameter holes on your dotted "spray" line , spaced/positioned longtitudenly "between" your Secondary holes
Cheers
John
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I guess the flat shape is fairly weaker than the cylinder shape of the tube, did you change your end caps out for thicker flat plate? How thick are your FT and combuster tube walls?