Turbine Test Rig design

[Fwann15]

I'm designing a turbine test rig, and for the air supply system, I'm thinking to have a compressor connected to an air receiver, then to a back pressure regulator, and finally to a converging nozzle connected to the turbine. There are some known variables, the turbine nozzle inlet diameter is 77mm, the mass flow rate at the inlet is suggested to be 0.7kg/s, and the compressed air should be around 7.5 bar. I'm struggling to find any air tanks/receivers that have an exit area of 77mm or higher, and I'm not even sure if this design is the best for my test rig. Will really appreciate it if anyone could suggest a better air supply system and where I can find the relevant components. Thanks!

 

[IRstuff]

You have to build your own, and ensure that the laminarity is consistent with what the turbine would see under normal operations.

Have you actually run the calculations? I get something around 1200 scfm, which is NOT something that a home compressor is going to get you. Home Depot shows

https://www.homedepot.com/p/EMAX-25...pressor-Cabinet-Only-ERI0250003-208/315481600

which outputs 104 cfm @ 40 psi and costs about $10k

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[Fwann15]

IRstuff, thanks for your reply! I'm not actually building it, I'm only designing one. Consider this test rig to be used for industrial testing, so it's not any home experiments and I'm not worried about the budget as well. My turbine is 1m in diameter, so I think a high scfm makes sense. However, from my calculation, I used an inlet mass flow rate of 0.84kg/s and an initial air density of 8.71kg/m3 at 7.5 bar and I got a scfm of 205 with is different from what you have calculated. Not sure if I have done anything wrong.

And I'm finding the right components for this setup. Currently, I'm considering an air receiver of around 24 gallons, but I would still need to find one which allows me to connect a >77mm diameter pipe to it.

 

[IRstuff]

scfm is defined by

https://www.pdblowers.com/tech-talk/scfm-standard-cfm-vs-acfm-actual-cfm/#:~:text=SCFM%20is%20normally%20used%20to,density%20of%200.074%20lbs%2Fcu.[/URL]]SCFM is normally used to designate flow in terms of some base or reference pressure, temperature and relative humidity. Many standards are used, the most common being the Compressed Air & Gas Institute (CAGI) standards, which are 14.5 PSIA, 68°F and 0% relative humidity (RH). This converts to a density of 0.074 lbs/cu.ft. for air.

Your inlet mass flow is 0.84 kg/s --> 1251 scfm inlet flow

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[IRstuff]

Conversely, you can look at the cited compressor's output of 104 scfm and convert that to a mass flow rate of 0.0582 kg/s, which is less than 1/10th of your notional requirement, i.e., you need something like 12 of those puppies to do what you want

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[Fwann15]

Thank you for the link. Isn't there some industrial size compressor that can do the job? instead of having 10 of them?

 

[IRstuff]

The rest is up to you

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[Fwann15]

I'm hoping to find a site that sells this type of size of compressor or air recievers, I don't know where I can find them.

 

[IRstuff]

It's likely custom-designed, since there probably aren't a whole bunch of people doing this sort of thing, and industrial compressors are intended for supplying pipe air for power tools, pneumatics, etc.

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[Fwann15]

Thanks very much!