Turboshaft Racecar?

[racket]

www.amazon.com/Gas-Turbine-Engine-Development-Applications/dp/0801957532/ref=sr_1_1?s=books&ie=UTF8&qid=1481417503&sr=1-1&keywords=the%20gas%20turbine%20engine%20%20by%20jan%20p%20norbye&tag=viglink20248-20 page 359

....................GE Firebird 111 en.wikipedia.org/wiki/General_Motors_Firebird

[rcman50166]

We'll the jet specs design seems to work okay. This is a reverse flow model. I'm going to try a few other kinds of entry flow to see what happens.

[racket]

Hi

If you want to do the combustor properly I'd suggest getting a good used copy of

www.amazon.com/Gas-Turbine-Combustion-Arthur-Lefebvre/dp/0891168966/ref=sr_1_3?s=books&ie=UTF8&qid=1484444453&sr=1-3&keywords=gas+turbine+combustion+lefebvre

used copies www.amazon.com/gp/offer-listing/0891168966/ref=dp_olp_used?ie=UTF8&condition=used

The Jetspecs combustor isn't the best solution , its a way to get a working engine , but seeing as you're going to spend a lot of hard cash on decent sized turbos to feed the combustor, you may as well get good value from it .

Invariably the Jetspecs combustor runs with a very hot cap , not the safest outcome , ideally you need the cap of the flametube to be stood off from the combustor cap with air entering through the flametube cap via a swirl vane set if using a single spray nozzle .

Cheers
John

[rcman50166]

Jan 14, 2017 20:49:23 GMT -5 racket said:

Hi

If you want to do the combustor properly I'd suggest getting a good used copy of

www.amazon.com/Gas-Turbine-Combustion-Arthur-Lefebvre/dp/0891168966/ref=sr_1_3?s=books&ie=UTF8&qid=1484444453&sr=1-3&keywords=gas+turbine+combustion+lefebvre

used copies www.amazon.com/gp/offer-listing/0891168966/ref=dp_olp_used?ie=UTF8&condition=used

The Jetspecs combustor isn't the best solution , its a way to get a working engine , but seeing as you're going to spend a lot of hard cash on decent sized turbos to feed the combustor, you may as well get good value from it .

Invariably the Jetspecs combustor runs with a very hot cap , not the safest outcome , ideally you need the cap of the flametube to be stood off from the combustor cap with air entering through the flametube cap via a swirl vane set if using a single spray nozzle .

Cheers
John

Book ordered! For $3 it really is a no brainer.

That flow analysis does not include combustion. The main focus is to see the direction of the flow going toward the injector area in the primary zone. It also appears to be very turbulent. This won't come close to modeling the correct conditions simply because I cannot add heating into the model.

'nother angle. Still figuring out the flow analysis.

[rcman50166]

Whew, sorry for the hiatus. The book I ordered nearly a month ago just came in today. Not surprisingly the package had a customs sticker on it. I'm going to try and take a chunk out of it before doing any more design. I'll post with questions.

[racket]

Theres plenty of good info in there, happy reading :-)

[trc]

Nov 28, 2016 20:08:38 GMT -5 rcman50166 said:

Hi everyone,

I'm new to the forums. Some background about me. I am an NDE technician for a major jet engine manufacturer (I don't care about disclosing this information, but they might). I have a mechanical engineering background and I'm a car enthusiast. I've joined the site to seek more advanced concepts to jet engine theory and design. I'm also looking for good places to start researching my project.

So what is it? Well the title pretty much says it all. I want to make a turboshaft powered race car. I mean driven wheels. This is by no means practical or economical so I'd rather not hear about how there are cheaper alternatives. It's something I've wanted to do since seeing vehicles like the helicopter powered minivan (one of your own), the Howmet TX, and turbine assisted vehicles like the Mannic Beattie. The scope is autocross or SCCA track day type stuff. The vehicle will be built from the ground up to accommodate the engine. It will likely be a small RWD, mid engined, open wheel car.

So what engine should I use? I'm looking for something in the 200-1000hp class. I want a low maintenance, low cost engine. I'd prefer single stage compressor and turbine with a separated power turbine. Blisk/centrifugal architecture is preferred. Looking around a Pratt and Whitney PW200 or something similar would be perfect. This is where my knowledge is lacking. I am unaware of what the big manufacturers make or how easy they are to get. Quantities produced greatly affects how many trickle into the private owner arena. I am also unaware of where any private citizen gains access to such equipment. This is knowledge I hope to gain from this forum. So any help in this area would be greatly appreciated.

Other talking points:

-Engine maintenance cycles and costs
-Power transmission to driven wheels
-variable guide vanes for power turbine
-throttle response and how to translate a throttle pedal into acceleration
-oil system
-fuel system
-gyroscopic influence of a jet engine
-chassis to engine vibration mitigation
-hot section metallurgy
-flow design and jet turbine architecture

[stoffe64]

How about a RR Nimbus? Or a RR Gem helikopter engine? Or a GE T58 helikopter engine??

[CH3NO2]

Dec 5, 2016 21:41:43 GMT -5 racket said:

Hi

I did some numbers for that big Garrett turbobygarrett.com/turbobygarrett/turbochargers/gtx5533r-gen-ii , the turbine stage is just too small to flow the compressors potential output :-(

.....

Cheers
John

Hello,

I am in the market to build a turbo jet and was looking at the GTX5533R. Research led me to this really fantastic forum JATO! (this place is awesome.)
Anyways, how is it you determine the suitability of a turbo charger in a Turbine application?

In your message above, is the turbine too small for the compressor based on the compressors input "power requirements" or is the turbine too small for the output mass flow?
Is the problem compressor stall will be encountered before it spools up? Or will the Turbine choke and not supply enough power to the compressor?

Would the 5533R be able to perform well if a degree of bypass was utilized? (I would like to be able to use bypass air if possible.)

I noticed the plots of the corrected turbine output massflow for a given housing and PR was quite a bit lower than the mass flow of the compressor... but I don't understand what the relationships between the compressor and turbine need to be.
GTX5533R maps


Thank you!
Tony

[racket]

Hi Tony

The GTX 5533R has a great compressor but the turbine stage simply can't pass the comps flow , OK in its turbocharger scenario as the pistons can force the gases through at higher pressures/densities than we can , our pressures going into the turb stage are always lower than those coming out of the compressor.

The Turbine Corrected Flow is equal to the Actual Flow times the square root of actual temp absolute degree R divided by 519 , divided by the pressure ratio going in .

So for a T I T of 900 C -1652F - 2112R and an actual flow of 180 lbs/min at 4.5 PR , 180 X ( 2112/519 )0.5, div by 4.5............180 X 2.017 div 4.5 = 80.69 lbs/min Corrected Flow , this is 15% greater than what the large 1.4 A/R housing will flow :-(

Bleeding off some of the comps flow generally doesn't help a lot as there then is an inbalance in the mass flows , with less through the turb stage it produces less power , so we need to increase temperatures to compensate , this then exacerbates the situation as far as Corrected Flow goes .

The GTX5533R is a great turbocharger but doesn't quite lend itself to being a great GT conversion , it undoubtedly would work as a GT with compromises , a bit lower T I T would help , but that then lowers final power output from the engine , increasing the PR to 4.75 would help a tad with getting gases through the turb but as efficiency from the comp is going down the higher we go with PR , the power output won't increase because we waste any potential increase by beating the incoming air harder.

LOL, if someone gave me a GTX5533R I'd certainly make it work ;-)

Cheers
John

[CH3NO2]

Thanks for the heads up on the 5533R! Its a costly part.
If the 5533R was a viable option, I would have built it with the intent to use 20%-30% bypass air for the after burner or for other combustion and flow experiments.
Air ~50 lbm/min @ ~10 psid.

If I was to build a turbine for use as a bypass air source, is it even feasible?

Thanks,
Tony

[racket]

Hi Tony

Its feasible to build an engine for bleed air purposes ...............LOL, my 12/118 jetandturbineowners.proboards.com/thread/612/fat-boy-118-thrust-engine would be a good example of the sized components you need

But 50 lbs/min at only 10 psi would require a very large turbo due to the low pressure of the bleed , it'd be easier if at 30psi as the engines comp would be flowing more air.

If you can elaborate on exactly what you'd like to achieve I'll have a better idea of where to point you.

Cheers
John

[CH3NO2]

For my purposes, the compressor and turbine could operate at as high a pressure as possible but I only need to bleed enough to maintain 10 psig at the bleed outlet. Higher pressure is always better but 10 is a minimum.

I can make an electronic closed loop system operating an electronic blow off valve such that the valve functions as a closed loop pressure regulator to maintain 10 psig at the outlet. That would be great. If the bypass, or bleed, mass flow exceeds 50lbm/min the pressure can roll off. That's OK.

If the compressor is operating at a hypothetical 30 psig @ 200 lbm/minute, I dont need to use all of it, just a portion of it.
The turbine will still need enough mass flow and pressure to keep the compressor up to speed.

And one other very important detail I didn't mention earlier... I would much rather use an off the shelf turbo charger if its at all possible.
A secondary option would be to mate a particular compressor to an appropriate turbine.

I have a local turbo manufacturer (Turbonetics) that is willing to match up a compressor/turbine for me. The Turbonetics engineer sent me a spread sheet with compressor and turbine data that he feels is a match for this application, but unfortunatly I can't upload it here.

[CH3NO2]

The fuel flow can be on a closed loop to maintain a constant turbine pressure as bypass mass flow changes.
Alcohol and/or Water injection can be used if needed.

[racket]

Hi Tony

If you're only needing bleed air, then the GTX5533R is probably being under utilised , you really only need a pretty standard ( cheap) truck turbo with "brass" bearings .

Probably best to aim for an ~3:1 PR - 30 psig where the map is widest and efficiency highest, even though theres a large waste of energy expanding the 30 psi down to 10 psi bleed pressure .

With full expansion through the turbine and a diffuser exhaust pipe there won't be any problems running a relatively "undersized" turb stage

On the GTX comp map if you design for 150 lbs/min at 3:1 PR at full bleed and high TITs , then with no bleed you'll be back at 100 lbs/min and still at reasonable efficiency and some distance from the surge line whilst running lower T I Ts ...............yep , its doable with the GTX55 with the 1.24 A/R housing

Your Turbonetics guys will be privy to info not available to the public with regards the turbine stage and will have a better idea of whats available to use

Cheers
John