Any real engineers here? Can anyone recommend a book on gas turbine construction? Like the actual construction not just theory and super simplified diagrams. I want it for my hoverboard research. I have spent a while researching compressors and turbines and practicing drawing them with CAD software and 3D printing models so I'm familiar with that part but I'm not confident about the rest of it. Major gaps in knowledge are the oil lubrication system and the combustion chamber. So far I've seen amateurs like myself hooking up two turbochargers and for the combustion chamber they always punch "flame holes" of increasing size but I don't understand why that allows stable combustion.
Bumping for interest... also I think I know one, let me try to find it.
>>7683122
Thanks. Post it when you find it.
Nobody here knows anything about turbomachinery? Should I take this to /diy/?
>>7683044
>Like the actual construction not just theory and super simplified diagrams.
I'm pretty sure that kind of in depth information is guarded by the handful of companies that manufacture gas turbines.
>>7684783
Seriously? Even for an old obsolete design? I'm not trying to make an F-22 here, I don't need Area 51 insider tips.
One thing I want to know is how much of it you can get away with building it out of aluminium? Turbine is a no-no obviously but compressor should be okay right?
>>7683044
>"flame holes" of increasing size but I don't understand why that allows stable combustion.
I think the most fun way would be to run a fluid simulation and play with it.
that's how commercial turbines are designed: tests and tweaks. these machines are much too complex for analytic theoretical solutions. Yeah, you can stack the basic principles together but they're not gonna translate 1-1 to a constructed product, because you can have anything from too much skin to eddies following an irrational attractor.
btw the holes increase in size so that the pressure gradient attains the proper shape and enhances the chimney effect.
>>7684865
you need to acquire some basic machine element/construction and fluid dynamics knowledge, that much is evident from the questions you're asking
start with this, after that you can think about what kind of book may help you specifically for turbine construction
>>7683044
Lubrication is easy part. Your oil selection depends on the speed and surface speed of the shaft. Other stuff like additives are good for numerous properties, but it really is basic. There are charts you can look up that have this stuff.
The combustion section needs to be set up so you can burn evenly and contol fuel flow. The nozzles as small enough to be volume limited (i forget the term).
>>7683044
I think I know more about turbine than you do, but I can in no way design a working turbine engine (beside the truck-turbo thingy ofc). So I first recommend you to try and learn a lot more about it, and try to build the turbocharger-turbine first.
>>7684865
Like when you have to ask this kind of stuff, you're not even half way.
>>7684851
or even a quarter way.
Yeah, let's post P&W or GE engineering drawings on 4chan, what could possibly go wrong
OP you are a dumb cockslut
>>7683044
Getting my bachelor's in ME in a few months. That's barely how construction works. You either grab a catalog and buy whatever existing turbine suits your needs or spend years drawing, simulating and prototyping.
>>7683044
you should think smarter, not bigger
Instead of building a gas turbine hoverboard, why not build a chainsaw powered skateboard
>>7685029
Skateboards don't hover my man.
>>7684866
CFD has too much of a steep learning curve for me I tried to get into it when designing airplane wings but eventually I just gave up and stuck with NACA airfoils for which there is plenty of written experimental data
>>7684907
I disagree, you can build a lot of things (a crude version anyway) without advanced knowledge of the working. Many amateurs build gas turbines simply by plumbing turbochargers together. They aren't GE-tier of course but they work. Besides as I said earlier I've spent quite a while studying turbomachinery and the relevant thermodynamic cycle. This is why I am not plumbing turbochargers together, I know the radius isn't large enough to give enough compression ratio therefore the efficiency will suck. I have a workshop I can mill or cut or lathe whatever, I just need to know the dimensions. I could trial and error this but I'd rather not waste money.
>>7684943
As a workshop floor engineer/grease monkey I find that students sell themselves short when it comes to their perceived ability to construct things. When it comes to actually making working parts manufacturing skill is actually more important than theoretical knowledge. I know people who never went to university who can build a radial engine blindfolded. Long ramble but my point is you should believe in yourself, don't be frightened off by the theory.
>>7685009
Yeah I know as I said when making RC aircraft I just select from a list of known airfoils. However in this case all the turbines on the market are either too small (coke can RC turbojets) or too big (actual full aircraft engines).
>>7684972
4chan chickening out of piracy? Who would have thought?
Mechanical engineer reporting in, working in structures
As some have stated, turbine engines are somewhat proprietary black arts. They are designed for a specific output, specific volumetric flow and size, they can be only made with a specific design that has been test or modified from previous empirical data. That being said, most of the designs from the second half of the 20th century are at the practical limit for efficiency and only differ in package. For example, the plane I'm working on now has an engine from P&W with an initial release date of 1972. That is, only minor revisions have occurred between then and now.
If you go down that route, there are many things to consider:
-Package size
-Volumetric flow (avoid supersonic flow by a good margin)
-Compression ratio (I believe most turbines fall around 18-24:1)
-Fan efficiency and design, as well as number of fans
-Gearbox (if using shaft power and not thrust)
-Fuel Injection design
All of this requiring at least a bachelors in engineering.
Other than standard thermodynamics books, two aerospace engineers pointed me to the same book: Aircraft Propulsion and Gas Turbine Engines by Ahmed F. El-Sayed. However, take this with a grain of salt; all aerospace engineers I have ever ran into have a severe deficiency in basic engineering principles except perhaps aerodynamics. Neither one of the two I asked would be able to calculate a Brayton cycle.
tl;dr It's all proprietary, and your best bet is to mimic or purchase another design.
A turbine sounds like an exhaustive approach when they sell kits to make a hoverboard with a vacuum motor; you should reconsider your scope. The ME club at my school helped freshmen and sophomores build a 2-person hovercraft using a 10-hp briggs and stratton and a industrial truck radiator fan. Cable controls and a jackshaft-propeller combo to control speed and direction. Worked damn well considering a team of 6 frosh/sophs and 2 seniors built it in three months.
>>7685183
Thanks.
>18-24:1
Oh boy that's a shock I was aiming for around 3:1 ratio. Was planning on using a single stage centrifugal compressor. 24:1 is crazy, no way am I ever going to get that out of a homebuilt dynamic compressor
>Fan efficiency and design, as well as number of fans
Not using axial the airfoil sections are too much of a pain to construct.
>A turbine sounds like an exhaustive approach when they sell kits to make a hoverboard with a vacuum motor
I want better power to weight ratio. I am using a piston engine for my current design however, this gas turbine is just a future idea. Thanks for the information.
>>7685183
And yes I know the efficiency will be shit at 3:1. I calculated that I'd get 10 minutes of hover time though.
Join your local Radio Controlled Aircraft club.
There are always people there playing with gas turbines. They usually have plans, contacts for parts and even where you can buy the cheapest ones.
Good luck with your project... And don't win a Darwin Award in the process.
/sci/ hyperloop team reporting in
doing a fan+compressor design ourselves, not from the scratch but it's impossible to get a price for them since they are exclusively supplied for the jet engine producer.
Does anyone know where or how to get a 1 m diameter fan and its compressor stages, with 10:1 bypass ratio and 30:1 compression ratio respectively?
Anyway OP I won't be posting links due to proprietary troubles but there are a lot of Rolls Royce booklets available that are super informative
Btw /sci/ Hyperloop team got accepted to the Design Weekend of SpaceX. If anyone with fan+axial compressor knowledge wants to join the team, email at
>[email protected]
Cheers
>>7685210
>single stage centrifugal compressor
Yeah, not happening as you stated. Typical gas turbine compressor blade will yield a 10% increase in pressure, which is why you have multiple sets of blades. It usually ends up being the largest section of the gas turbine. The reason for this is that the small differential minimizes losses and the blades are optimized for high volume flows which is a trade off.
>>7685394
Nah I've seen it done, the efficiency is god awful but it werks. IIRC centrifugal compressors have a higher pressure increase per stage than axial. Early jet engines just used one centrifugal compressor. The reason for the switch was because staging centrifugal compressors requires awkward piping, don't think I've ever actually seen a design where they were staged, they just made it wider which you an only do up to a point of course. Axial is obviously really easy to stage.
>>7683044
look kiddo, if you want to make a hoverboard, you best learn some theory. Cause jet powered hoverboards don't exist yet, you're gonna have to do some engineering.
But hey if you just wanna copy some design here's a bunch of fucking plans:
http://www.john-tom.com/html/Jet.html
Good luck machining them. HAW HAW HAW!
>>7685584
YES
Thank you so much anon.
For some reason I feel that I am now on a watchlist though.
