|
Post by enginewhisperer on May 15, 2024 5:43:08 GMT -5
I'll play with some ideas once I see what parts are available
|
|
|
Post by enginewhisperer on May 15, 2024 4:23:51 GMT -5
I remember that one I'll have a rummage around for bearings, possibly even repurposed from other bike engine parts. I don't really want to pull bleed air from the gas producer if I can avoid it, but it's probably possible if necessary. If I have to lubricate high speed gears etc anyway though I don't mind doing a full closed loop oil system for the turbine shaft bearings.
|
|
|
Post by enginewhisperer on May 15, 2024 2:30:27 GMT -5
ah that would make sense if they have turbine wheels designed for ball bearings.
I'll see what I can find, but the info I have rates the common 17mm bearings for 28-30krpm, and 20mm bearings for 17-22krpm.
Realistically it's not going to be going over 30krpm very often, but it would be nice not to have to worry about it. A good oil supply with the brass bearings shouldn't cause any suprises, but I do like the simplicity of using ball bearings if possible (don't have to make the thrust washer setup etc)
|
|
|
Post by enginewhisperer on May 14, 2024 22:07:56 GMT -5
Do they machine the shaft down or something? I have plenty of good quality 15 and 17mm bearings kicking around I should also have some larger ones, maybe 20mm. I could make a sleeve for the shaft to make it work with larger bearings, but from memory it's starting to push the limits on RPM with the larger bearings.
|
|
|
Post by enginewhisperer on May 14, 2024 20:01:08 GMT -5
Yeah I already have a suitable electric oil pump or two, so not too worried about that. I'll have more of a look for bearings but all the 16mm ones I can find are for trolley wheels and I don't think I'd trust them at 40krpm!
|
|
|
Post by enginewhisperer on May 14, 2024 18:49:21 GMT -5
In Australia I can get any number of high quality bearings with 15mm or 17mm ID but anything 16mm is either very expensive or coming from overseas and / or of questionable quality. I'll have more of a look, but I figured with a decent oil system the brass bearings would go ok.
I will have a high pressure electric oil pump for the gearbox.
|
|
|
Post by enginewhisperer on May 14, 2024 17:53:44 GMT -5
Nice project ! Looking at your CAD may I suggest that you use ball bearings instead of those hydrodynamic illustrated in your design. They will not last long from the radial load caused by the gearing torque. I was originally expecting to use ball bearings but didn't find anything much available with a 16mm bore to suit the shaft. I could make some collars and run larger bearings, but they start getting pretty big for the RPM involved. I was thinking about adding an extra ball bearing on the other side of the gear, or I could potentially put a ball bearing at the gear end of the shaft and leave the hydrodynamic one at the turbine end? I could also replace the thrust bearing arrangement with a ball bearing. I'm not too worried about bearing life span because chances are this thing won't get a lot of use, but it would still be nice not to worry about this stuff at all. Definitely open to any suggestions here! Here's a video of the P4T test run:
|
|
|
Post by enginewhisperer on May 14, 2024 3:49:03 GMT -5
I should probably start a thread for this project Early this year I picked up a JetCat P160 RC jet engine for a good price with 1 hour on the clock and some minor fire damage, apparently due to a fuel line coming off during startup. After replacing all the fuel lines and giving it a bit of a checkover I found there was some junk in the start fuel solenoid which stopped it from closing. This may explain the previous owner's fire! I figured it would go well with a freepower turbine, and I had a couple of Holset HX83 turbine wheels kicking around thanks to another JATO member! After talking to John I did a test run with a jet pipe pressure probe and he worked out that the larger of the HX83 wheels should be able to extract maybe 40hp, which would make it pretty entertaining on something like a light weight motorcycle. As usual, I jumped straight to the last step and found a suitable bike for it to go in. It's a Yamaha R15, which apparently has about 19hp in standard form. I wanted a bike with cheap registration costs and a full fairing so I can hide the turbine setup in it and at least ride it around the block before I get sick of it and return it to standard form! I've since been searching for suitable reduction gears, and might end up using a combination of primary gears and parts of the gearbox from a scrap CBR125 engine to get the ~9:1 ratio needed. I started designing the shaft tunnel for the turbine shaft and mocked up the first stage of gears in CAD. To get the profile of the turbine wheel I put it in the mill and used it to machine some foam, and then scanned the edge in a flatbed scanner. It's easy to import into the CAD sketch with the correct scaling and just draw over the top of it. I'll probably 3D print a test piece to confirm the clearance for the turbine shroud. I'm not sure if the shroud will be CNC milled, done manually on the lathe, or maybe pressed / spun from a piece of tube. The next step is probably to design the scroll housing in some form that I can hand make, and once I know how much space it needs, work on the rest of the gearbox design.
|
|
|
Post by enginewhisperer on May 14, 2024 3:19:45 GMT -5
that would make sense. I thought I remembered something that looked like that from years ago!
|
|
|
Post by enginewhisperer on May 14, 2024 0:46:00 GMT -5
I think some of those are new products. I don't remember there being 5" or 6" ones before. I hadn't seen the carbon fibre one before. Nearly had to order one of those except it'll be hard to weld to my aluminium intake pipe
|
|
|
Post by enginewhisperer on May 13, 2024 23:20:57 GMT -5
Aeroflow is in Sydney I can probably get some of those bits at trade price if you need them. I think the aluminium ones are 1.6 or 2mm thick. I have a 4" one at home I can check.
|
|
|
Post by enginewhisperer on May 9, 2024 20:49:20 GMT -5
you didn't have to spam everyone else's threads with this. It makes it look very scammy. One post would have been fine.
This is a great way to get your account banned.
|
|
|
Post by enginewhisperer on May 8, 2024 16:30:40 GMT -5
a lot of turbos (eg MHI TD series) have individually balanced components and it is standard practice to replace a compressor wheel without balancing the assembly. It's probably not as good as a balanced assembly but for lower performance parts it's certainly not an issue.
I wouldn't be too worried about it for a turbine that's just aiming to self sustain - as long as the turbine wheel / shaft has been balanced and the compressor wheel has had some sort of factory balancing.
|
|
|
Post by enginewhisperer on May 5, 2024 19:26:45 GMT -5
Okay, and if my gas turbine doesn´t have this step, it will affect a lot? it doesn't need the step on the back of the diffuser, but you do need your compressor wheel outlet to be flush with the front side of the diffuser - which will generally mean having a small recess there.
|
|
|
Post by enginewhisperer on May 5, 2024 4:37:29 GMT -5
that step looks to be a recess for the compressor wheel to sit in, so the face of the diffuser is in line with the "front" surface of the compressor wheel.
Baically there's a step in the metalwork to prevent a step in the air flow.
|
|