Very good job, congratulations. As someone already mentioned, You should read Kamps article on microturbines, there is much information and calculations there. What I can say is that the combustion chamber seems to be a bit long. Also, the blades of the NGV needs to have the right angle. And above all, the bearings. The full ceramic bearing can not withstand the high RPMs. Try buying the ceramic spheres and build the bearings. The inside and the outside of the bearings are made from stainless steel. You can use an existing one as a base.
Haven't had the time to read but definitely will before reattempting this. The way I built this turbine... it's not suitable for rapid prototyping. This seems like a highly empirical field so I may try 3d printing in ceramic or something to test different parameters especially for the ngv. Or... Of course just copy someone else's design but what's the fun in that. With ceramic bearings, would you clarify on why full ceramic isn't suitable for high speeds?
I am building an engine too🤠, but you are a little ahead of me... so many things to learn. The fluid dynamics of an engine that is moving are different than an engine standing still. When an airplane is flying air goes in the engine mostly from the front. When testing an engine on a test stand a lot of air gets sucked in from the side. Air getting sucked in from the sides can cause a shockwave at the front of the engine that stalls the compressor. The way to get around that problem is to use a bell(trumpet shaped) cowell for testing. The length of your cowell to your turbo is almost non-existent. It could be slowing down your RPMs. In big jet engines ( just because your's is only a few inches long doesn't mean that it's a toy) the combustion of the kerosene is supposed to be completed and the gas already cooling off before it hits the turbine. Kerosine burns at 2,000C. Steel melts around 1,200C. Titanium melts around 3,000C but it burns around 700C. Molybdenum melts at 2,400C, but it burns around 640C. Big gets are made out of a nickel alloy that melts around 1,500C. The gas has to be cooled to 1,100C before it hits the turbine so that it isn't destroyed. The newest metal to be used in jet engines is niobium C-103. All of these fancy metals cost money. If you have a magnetic induction heater, maybe the lowest cost way is to get unservicable turbine blades from a big engine and melt them . If the turbine stator is glowing yellow, the gas hasn't cool enough before getting there. The way to fix that is increase the length of your flame holder, or have more cooling air that bypasses the flame holder to the turbine. Your flame holder doesn't have much color on it, so there is a good blanket of air between the metal and the flame. There are two kinds of bearings and jet engines need both. You already have an axial bearing, but you need a thrust bearing in the front and back end. [radial bearings reduce friction perpendicular to the axis, thrust bearings reduce friction parallel to the axis] For anybody that is trying to build their own engine, the bearings are one part that you can't make yourself. Because it is one of the most important parts, it's a good idea to buy your bearings first and then build the rest of the engine around the bearings. This is one of the thrust bearing that I am looking at to build a jet engine www.mcmaster.com/product/5909K24 www.mcmaster.com/content/bearings/ball-bearings-4 trying to find radial bearing and thrust bearing with matching sizes and RPM ratings is frustrating. The higher the RPM rating the more you can push it without overheating.but the higher the rpm the less choices of bearing there are. I wish you good luck with your second build. I am still collecting pieces for my build. Making a small 2-stage oil cooled axial engine is turning out to be crazy. lol I should have taken the easy route with a centrifugal engine like yours🥸
Your very knowledgeable indeed! I'm aware of these ideas too and have tried to address them in the design, though to vary degrees of success. Your note about the combustion chamber colouring is appreciated, but I believe the reason no visible change is observed is because it is already entirely oxidated after I heated the entire thing as a test. Poor choice as it would have been a great diagnostic tool to see the temperature distributions. Best of luck with your build. Is 2 stage axial even going to have any significant compression? How will you source (or build??? Impressive if you do) the rotor and stator?
That is by far one of the best home made designs I've seen so far 👍👍, I'm so intrigued by jet turbines I've built two small ones using stainless steel coffee mugs ,I'm building a third one , this time it has a two stage compressor, can't wait to see how that works out for me lol, thank you for your video, it was very informative, great job 👍👍 ✌️😎
I also wanted to build one years back and at that time due to cost of bearings I decided to use a point bearing on ends. Also I see a problem why it's not sustaining, because there is too much air exiting the chamber. You need to add a shield in the turbine side to reduce airflow so that flame stays stable in the chamber and you get more preassure build up in chamber
To reduce the combustion chamber outlet area (but not the holes on the combustion can itself), am I understanding correct? Another commenter also suggested such a thing, I will try this in the next iteration.
Is that your own design? Very impressive. I'm particularly impressed with the way you made your diffuser (but I don't think the design is correct): The vanes on the diffuser need to be at a particular angle, to suit the compressor wheel / RPM (have a look at Kamps or KJ66 designs for reference) and benefit from being spaced away from the edge of the compressor wheel (the 'vaneless space'). The passageways in the diffuser need to increase gradually in cross section for their full length - the step you have where the casing fits is a big no-no (you would need a bigger casing). I don't know if it will work if you fix these things, but it would stand a better chance. If you can get hold of the Thomas Kamps or Kurt Schreckling books, they have all the information in them to allow you to evaluate the design of the engine and figure out how to improve it / whether it will ever work. (The yellow Thomas Kamps one is still in print). I think you may have problems with balancing if you're using 'C' clips on the rotor, and they may not survive running RPM (they are likely to be ripped off the shaft by centrifugal force). I'm not sure how well the turbine will work with the cut-off front edge, but getting the design right is the most important thing. Kudos for getting as far as you have. 👍
Thanks for your advice and kind words. I'll try to find those resources you mentioned, but I don't have too much time at the moment to work on this project. Interesting suggestion about the vaneless space, I assumed you'd want the vanes to be as close to the impeller as possible. I'll have to look diffuser design more, those books may be a place to start.
24:14 , I like your threaded, air tight, rear axle. That way, the high pressure hot air can not leak from combustion chamer through the rear bearing to the nozzle. Most model jet engines don't have the air tight thread, and they just bolt on the case without sealing gasket because no gasket material can withstand the hot air.
Just subscribed, I do have an smaller turbine... but i need to deal with the balbearing on the rear.. it usually gets destroyed with in a few minutes... May I inquire where do you purchase the ceramic bearing??
i'm confused, how's the lubrication system works? is it not going to mix with the fuel? or is there some type of seal to contain the oil. any inputs would be a big help
Actually the lubrication system doesn't exist. My assumption is that the ceramic bearings could operate at temp without any lubrication. Which is probably not a standard or reliable solution.
Hi Tamas lot of effort there but you could do to get Thomas Kamps and Kurts books they explain a lot of things . Compressor Air must pass down the bearing tube to cool the bearings they are only 20mm from 650c to 700c turbine temp . 5% oil is mixed in with the fuel and is Teed off from fuel line metered down to 5% of the flow to the engine injector needles and is feed to the front of the front bearing passing down the bearing tube to lube and cool the rear as a total loss system getting burned up in the exhaust. The force on the turbine wheel will may be rearward as the drag on the wheel with the air/ Jetstream leaving is giving the thrust ;the compressor will tend to get pulled forward with the low pressure in front, most engines went to front preload because of this or ran high rearward preload. Your diffuser may work but you need the wedges to be same diameter as the case or you are expanding and contracting the air. also you need a gap between the diffusor back and the combustor front to let air get through to the middle of the the combustor. looks like your bearing tube is blocking the airway. You turbine wheel looks like a radial turbine wheel with the back face machine off but the pass area will be too big don't know any of your sizes but blades need to be about 12mm high for about a 66mm dia. maybe better to make a flat sheet twisted axial turbine wheel as Kurt did . Your combustor dilution holes at the rear should have the vaporizer tubes in between not blowing on the tubes as this will cool them. can't see the inner combustion tube .the needles for fuel look too long the idea is the fuel is injected/smeared on the inside of the tubes were it is heated and vaporized ,the needles should touch the inner wall of the tube not shooting it straight down the tube. You mention alcohol for fuel ? best to use Paraffin or diesel fuel alcohol is more of a degreaser not good for the bearings. doesn't Thomas book gives all the size's but best to stick with a design I have never designed one of my own .
Hi reedy, astute observations there and indeed very good points. Many commenter have suggested I take a look at that book so I certainly will before any major rework but your suggestions are good. Looks like you've built your own turbine too? I went way over my head designing my own turbine but it's been a great learning opportunity for sure.
@@tamashamas6193 would not have written such a long reply but you have put a lot of work into it I am impressed with the sand cast diffusor ,as a eyeball check a line through the the wedge should be 90 degrees to the compressor blade tip . you could try thinning the bearing tube flange to 4mm thick on the screwhead side and use countersunk screws you don't want them 3 large holes at the front of the combustor a spot welder would make life a lot easier for welding patch's over the holes, you don't want away gaps at the front as very little air is needed for combustion , The injector needles don't want to be bigger than 0.8 mm o/d or you will get a hot spot at the bottom of the NGV outlet.. Think i have a overview on my channel of the Kamps book Kurts book on the fd3/64 and KJ66 ,Kurt has also done books on turbo prop and turbo fan engines amazing guy at one of the GTBA talks he flew a heli powered by a fd3/64 driven off the compressor suction you get about 2hp this was in about 1996 . I have built a turbine or 2 Kamps ,KJ66 and FD3/64 all on my channel .not many early runs when it was on near melt down.
I might go for a full combustor rebuild. Earlier you mentioned building a custom turbine, which I waved off as being impossible to build diy and also be balanced. Furthermore, I didn't consider any of the materials accessible and machineable suitable but I suppose running cool enough makes stainless and option. I also recently saw an interesting method for propeller forming using a hard and thermally more resistant die which the rotor material could be formed against after being heated, this might be worth a try? The die itself could be made by roughly grinding tool steel for instance into the shape each blade should be. Repeatability is possible without needing inaccessible cnc machines. I'll look into this more but in general I want to approach my next attempt with simpler manufacturing to allow rapidly prototyping.
@@tamashamas6193 stainless steel is ok but stay below 600c(550c better) and don't go over 80k to make real power you do need the correct metal but as you say hard to machine . if you make your own turbine you need to use 8mm thick boss and turn a centre boss but get Kamp's book it will show dimensions. making a die would be a big undertaking you need to thin the blades at the tip and leave the root thick /rounded grinding the blades is the only option once you start its not to bad just do it in stages the balance can be done as you grind by checking the thickness as you get near to 0.8mm at the tip and when you do the balance look to correct any blades that are on the heavy side .
@@tamashamas6193 Hi, friend. I'm from Chechnya I'm from Russia, I'm a Chechen by nationality, here in Chechnya they accuse me of many things that I didn't do, I want to somehow leave here, But I have neither money, nor means, nor health. You can collect some planes to fly for me somewhere on the territory of Russia. Then take me and leave back, I beg you, tell me what country you are from.
Excellent Job, Try with compressed to avoid fuel, so what happens to the turbine. Does this jet engine throws high velocity exhaust? most of the work goes in spinning the turbine blade fans
@@tamashamas6193 My concern was that if the burning of fuel going to spend all its energy in spinning the turbine blades, then will this turbine propell the jet forward
An efficient system will leave some energy in the exhaust which can do useful work. My setup is not, It cannot even extract enough energy to self sustain. So next iteration will need to improve efficiency + more aggressively choke the flow before the turbines.
Do you think axial flow or hybriz engine could be functional in a similar scale? I am in the process of making a jet engine myself. The body will be somewhat larger. The problem with the crntrifugal compressor is the complicated design and cost. Perhaps an impeller pump and a couple fans in front could be used to compress air into the chamber?
I considered such a design, I dont remeber the details as clearly but I decided against it for the following: 1. There is no readily avaliable commercial sale of axial turbine impellers. Whereas the centrifugal impeller is mass produced for automotive turbos. Geometry perhaps not optimal at low rpm, but a compromise that's necessary due to budget. 2. Axial turbines require multiple stages to attain the same pressure ratio as a single centrifugal. This is desirable in my small build, maybe at your scale it becomes worth the added complexity. Especially considering each stage requires a stator too. Not very simple to make. I don't know what manufacturing capabilities you have, I trust you to make a judgement.
I got my hands on an old leaky turbo. The fan is a bit small so I'll add another fan in front of it for added pressure. Don't have time to recheck the video but how do you manage cooling? Do you simply use low temperature fuel, liquid cool or is the air flow enough to keep this cool enough not to break? Also do you have room for thermal expansion?
Are you talking about cooling the bearings? If so, my setup is air-cooled and uses ceramic bearings. I wanted to avoid needing to seal the bearing chamber which is necessary if flowing extra coolant. Thermal expansion isn't really managed, in fact this might be why the rotor seems to vibrate more as the engine warms up.
Thanks, the casing is from a Thermos mug. You wouldn't believe the looks I got pulling out calipers at the cookware store. What confused me about the carbon build up, it was kinda sticky... Either way, that build up shouldnt have ended up on the casing itself so something to troubleshoot there.
@@tamashamas6193nice! Haha must of confuse other ppl. Hmm im not sure why it would be sticky besides from a coating or something used when the mug was manufactured. But yeah refine your jet engine its a must after seeing how well it preformed
Incomplete combustion forms deposits… dry the fuel to remove water and solids… which is probably why it’s sticky. Sometimes dyes or flavorings to prevent drinking put in stuff causes this gunk
The yellow bottle heet burns very clean. Have u tried that yet? Make sure it's the yellow bottle not the red one. White gas does burn fairly clean but I think the yellow bottle heet will have a more efficient combustion. Happy testing!!!!! I'd like to see more of your creation
@@tamashamas6193 The engine should already start to run selfsustained at a pressure of 0.1 bar to 0.2 bar. Actually it is not the internal pressure which is of interest, but the flow speed and amount of air passing the system to produce thrust. Pressure and flow are of course somewhat linked together, but having a high pressure with almost no flow, will never run. The vanes angle on the diffusor is IMHO too shallow. It has to be more agressive. 25:00 it looks like the outer race of the ceramic ball bearing can spin freely. That is probably because aluminium will expand quicker and wider under high thermal conditions than the bearing is able to. Another thing I noticed: the tubes covering the fuel inlet needles seem to be very short. Do the needles stick out of the tubes? If so consider to extend the tubes. The heat from the tubes will heat the fuel in the needles when doing so and the fuel will enter the burning chamber as vapor. You may want to consider to use propane/butane instead of methanol. It is easier to ignite and to get a successful and self-sustaining combustion. Progress to petro/diesel/kerosine when that combustion works and finally go for methanol. Strive for the low hanging fruits first. You don't know if the engine will be able to run at all. So why not ruling out some unknown. And as for loop already is asking, what about leaks? Don't underestimate the power of air. 1 bar can press water in a column 10 meters high. The stress put on materials and seals is tremendous. I just saw some weeks ago a video with a transparent engine housing. It was clamped down and the seals were massive and tightened very serious. The seals simply got squezed out of their seats and were completely displaced after the engine spun up into the higher regions of rpm. But a nice looking project, buddy. You are on the right way. Keep on rocking 😃
@@Jan_Seidel hello Jan, Thanks for taking the time to type that up. Those are some interesting thoughts, I very much appreciate your feedback. I assumed running off any liquid fuel would be more effective than butane alone, simply for the much power delivered through combustion. Those tiny camper canisters cannot sustain high flow for very long. The needles do not extend pass the tubes, so that should aid in evaporation. I chose methanol since it is known for volatility, hence it should burn more cleanly even if my mixing isn't so great. I will attempt something else next time. This probably isn't the most critical issue however, a good turbine should run well on any fuel I'm guessing. The more critical issues are probably what you have pointed out. The pressure and flow rate are a function of engine rpm and the geometry of the internals. However combustion efficiency is only a function of pressure. Is this correct? The turbine used is from a turbo and apparently require much higher rpms, since they are design for efficiency. There is still much vibration in the rotor, and I am unsure how I could reduce imbalance. Preventing the high rpms needed. Diffuser geometry is something I could adjust as you suggested. However given I am no aerodynamicist I'm unsure to what effect those adjustments would provide. I will probably take your advice. Engine leakage is probably a big issue but as mentioned, not much pressure is being prodcuued so far, but this is definitely something worth working on. Currently the casing has no way of being clamped onto the diffuser, so sealing is quite bad. And indeed I think I know what video you are talking about. That was quite amazing. Shows me how far to go I still have, my engine is far to flimsy and not at all precise enough. Nor am I confident in the deeper dynamics of such a engine. Hence some design choices were simply made based on intuition. So apologies if there appears to be any blatant ignorance.
How did you get the curvature for the intake for the turbine to 3d print it? also what is you instagram I am doin a similar project and I wanna exchange idea and talk
