|
Post by Johansson on Mar 4, 2024 16:10:16 GMT -5
Thanks!
Once I have it sorted out and running I have a feeling that it will idle at really low rpms. A push with the hand sends it spinning for 10 seconds and the 500mm turbine wheel will produce lots of torque for turning the compressor.
Next up is the NGV, this evening I made a drawing for the parts needed and will try to get them laser cut at work. I have no thick stainless at home so I might as well save me the trouble of hand making a 300mm disc with bolt and cooling holes from a 5mm sheet.
|
|
|
Post by Johansson on Mar 4, 2024 14:30:24 GMT -5
The "Pet-Processor 2000" has dried and is installed on the shaft.
|
|
|
Post by Johansson on Mar 4, 2024 12:09:19 GMT -5
HAHAHA! That was a good one! )
|
|
|
Post by Johansson on Mar 4, 2024 0:22:03 GMT -5
I don´t know why but red came to me as the natural compressor color. I ran out of paint before I could put a last layer inside the comp wheel but I figured who cares.
|
|
|
Post by Johansson on Mar 3, 2024 13:10:08 GMT -5
The compressor wheel is red enough and set to dry on the fridge lid.
|
|
|
Post by Johansson on Mar 3, 2024 9:14:42 GMT -5
The shaft tunnel is finished now, but I won´t paint it until the engine is finished since I would scratch the hell out of it during the flame tube construction. The NGV flange is small in diameter so I can get the flame tube past it during assembly/disassembly. When the metal epoxy had cured I painted the compressor wheel with red metal paint, a layer more is needed for acceptable coverage. Cheers! /Anders
|
|
|
Post by Johansson on Mar 3, 2024 3:14:16 GMT -5
It is a wet and rainy winter sunday today, a perfect day to get something done in the workshop. I welded a bit more before breakfast and cleaned the compressor wheel for gluing, I searched the shelves yesterday and found a kilogram of Belzona industrial metal epoxy. Can´t get much better than that, funny that I forgot about those cans. Lots of dead fishes and acid warning labels on them so they must be good. My plan is to get the shaft tunnel finished today with welds and strengthening fins, but we´ll see how it goes.
|
|
|
Post by Johansson on Mar 2, 2024 15:23:44 GMT -5
I didn´t get kicked out of the house today, but I fled to the workshop when the Swedish Eurovision auditions begun on the tv. The star of tonights show was a mentally ill man dressed as a street prostitute, a new and world encompassing Carrington event would be a blessing at this point... The gap is evened out around the compressor wheel as I told you yesterday, I also made a flange for the NGV. I added some welds to the bearing housings as well, I will do it a little at a time to keep things from heating up too much. A number of strenghtening vanes will be fitted between flanges and the shaft tunnel later, all weight is hanging from the bearing houses so they need some support. Cheers! /Anders
|
|
|
Post by Johansson on Mar 2, 2024 5:08:43 GMT -5
Hi Anders LOL.............can you bribe your daughter to have more friends over more often :-) Rotor looking amazing ..............now thats BIG . Cheers John I have passed the "difficult" diaper years with the kids so no one is missing me if I spend an hour or two in the workshop, it is mostly finding a balance between running, doing gun stuff and the workshop. It is pretty big, the blades are stiff in the sense that I can´t bend them by hand so hopefully the wheel will hold its shape even when spun and heating up. What do you think about blade profiling? With the size of the wheel a 3mm edge on the blades is perhaps not a big deal, on a tiny KJ-66 turbine the need for sharp edges is more evident.
|
|
|
Post by Johansson on Mar 2, 2024 3:29:14 GMT -5
For some strange reason my Onedrive account is blocked, so all images posted in the thread so far are gone. Hopefully it will solve itself but until then I upload the images to JATO. Yesterday my youngest daughter had her friends over for a birthday dinner, a strange feeling to be kicked out of my own house. In Sweden there is a children story about Emil i Lönneberga where a kid who makes lots of unintended pranks gets locked in the wood shed until his father calms down. I got those vibes last night when I was ordered to go to the workshop and stay there for 3 hours. The turbine blades are all profiled and twisted now, closest to the root the twist is not as good as I had hoped for but it is what it is. The main portion of the blade has the 30 degree exducer angle I was aiming for. I didn´t take a picture of it but I also evened out the gap around the compressor wheel. Cheers! /Anders
|
|
|
Post by Johansson on Feb 28, 2024 1:41:56 GMT -5
Holy crap that is shiny, good job!
|
|
|
Post by Johansson on Feb 27, 2024 1:40:18 GMT -5
We´ll see how fast this contraption can be spun before things go downhill, for the gen2 version I am tempted to try a single blade approach with hollow sheet metal blades locked by pins (similar to fir tree but with round holes in the disc instead).
With a series of 3D printed press jigs I think it would be possible to make them, a 1mm folded blade tig welded together along the inducer and exducer edges. Holes radially drilled in the disc to supply cooling air to the blade internals.
The compressor wheel shouldn´t have the same problems with the holes since it is in one piece, holding itself together and not pulling on the bolts like the segmented turbine blade arrangement.
|
|
|
Post by Johansson on Feb 26, 2024 15:43:55 GMT -5
True, but since the blades are laser cut to .1mm tolerances the balance in the un-profiled wheel is probably as good as it gets, profiling the blades and then statically balancing the wheel will most likely make it worse. I have to do any profiling by hand, flap disc style. Milling the blade profile would awaken vibrations from the outer regions of Hell... Shame you can't just get it red hot and squish it into shape with a few tonnes haha save the grinding nightmare. Sure you can rig up some setup to keep the grinder in the same position for each blade, like a diy surface grinder I don´t think it will be that much of a headache to profile the blades, if I weigh each segment before and after profiling I should be able to make them pretty identical. If this proves to work it is still a very easy way of making a turbine disc compared to turning a big chunk of inconel into a disc and manually grind out each blade from solid. Just need to improve on the lowest hanging fruit which seems to be the blade segment holes, until I can get a decent performance out of the design.
|
|
|
Post by Johansson on Feb 26, 2024 14:11:36 GMT -5
Remember turbos are usually balanced to a high level since even a tenth of a gram at high rpm is a lot of force so any weight you can shed that is further away from the axis of rotation will benefit you, plus profiling makes it better for flow so win win. You could probably profile before twisting, use an end mill or HSS radius cutter after you do the slot cut on each blade segment? True, but since the blades are laser cut to .1mm tolerances the balance in the un-profiled wheel is probably as good as it gets, profiling the blades and then statically balancing the wheel will most likely make it worse. I have to do any profiling by hand, flap disc style. Milling the blade profile would awaken vibrations from the outer regions of Hell...
|
|
|
Post by Johansson on Feb 26, 2024 14:10:56 GMT -5
Good find, it looks like 12.9 steel shoulder bolts are the way to go.
|
|