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Post by finiteparts on Jul 26, 2014 12:17:36 GMT -5
All, I just wanted to put up a link to an interesting paper that shows cross-sections of some small turbojet engines that were produced for drone engines. Pages 16-20 show the cross-sections. There are other sources of information on several of these... www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA256320I thought a new thread might be a good way for us to share some of the good info that we find with everyone and make it easy for us to access it when we need it. ~ Chris
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ripp
Veteran Member
I'm sorry, I don't speak english, so I torment you (and myself) with a translation program,Sorry
Joined: January 2013
Posts: 227
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Post by ripp on Jul 26, 2014 12:45:18 GMT -5
Hi Chris!
Thank you for sharing.
regards
Ralph
translate.google.at
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Post by finiteparts on Jul 26, 2014 13:10:56 GMT -5
There is a wealth of information out there on gas turbines designed for automotive use. The work by General Motors might be the most famous of that, but almost every auto manufacturer got on the gas turbine wave for a while anyway. Usually the cost of the components and the specific fuel consumption drove the final nails in the coffins for these programs, but there were some successes. GM sold theirs to the US Army as a drive train for some vehicles and also as a stationary power generation module. There is a a lot of good information for us to use in our design work. Here is a set of nice reports on the work done by the famous Chrysler team... www.turbinecar.com/misc/SAE-Turbine/Here is a great review of the larger engine developed by Allison/Detroit Diesel...of particular interest here for the homebuilder is that they chose to use a radial turbine wheel for their free turbine section. ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19870002562.pdfHere is a link that shows how Toyota delved into the GT space... www.tytlabs.com/english/review/rev411epdf/e411_001ohkubo.pdfThere is so much more out there. Searching NASA's Technical Report Server will yield a ton of hits...great stuff out there! Enjoy! ~ Chris
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Post by finiteparts on Jul 26, 2014 13:47:37 GMT -5
Another great resource for gathering information is Patent searches. Once you stumble onto a good patent, the cited documents section will lead you to even more great stuff. A great example for the homebuilder community is US Patent 4,825,640 which is a patent submitted by Sundstrand Corporation for an enhanced cooling scheme for their radial turbine "monorotor" expendable turbojet engine. The patent art shows the general arrangement of the small turbojet they offer... which looks similar to their TJ-90 engine shown previously in the earlier post in this thread. In US Patent # 8,438,858 also from Hamilton Sundstrand, we get these nice images, which might be of more value to the homebuilder since we can't really make out turbocharger bits fit together like a mono-rotor without significantly weakening them: and this sweet exploded view, There is also a nice bit of technical information given in the patents as to why their patent solves the particular problem and you also get to see the inventors. You can then sometimes find more information that the inventors have published in the technical literature such as ASME or SAE journals. This is how I came upon the AIAA article on the development work that Hamilton Sundstrand has been doing on miniature turbojet engines, their TJ-50, TJ-120 and TJ-30. arc.aiaa.org/doi/abs/10.2514/6.2003-6568Interestingly, they do not talk about the TJ-90 that showed up in the Australian Dept of Defence paper cited in the first post of this thread. I hope you enjoy looking through these as much as me! ~ Chris
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Post by racket on Jul 26, 2014 17:40:24 GMT -5
Hi Chris Not to forget the original turbine car manufacturer, Rover www.rover.org.nz/pages/jet/jet5.htm who built the first Whittle aero Jet Engines , and their famous record holding/setting 150mph JET 1 car of the early 1950's . The Chrysler engine was a great engine in unfortunately a crappy chassis , if only it had been fitted to an "English chassis" rather than a couple of tons of soft suspension'ed family auto . The great high pressure ratio Ford turbine engine with its two stage compression was another interesting example , ............... lotsa stuff on the Net these days , more being added every day :-) Cheers John
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Post by finiteparts on Jul 26, 2014 21:10:33 GMT -5
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Post by racket on Jul 26, 2014 21:51:34 GMT -5
Hi Chris
Yep , the Pistons to Blades book is a good read , I purchased it direct from the RR Site , it arrived from the UK to Oz in 3 days , they must have sent it via Concorde, the fastest delivery I've ever had , even faster than domestic purchases .
I just ordered one of the Norbye books , I've got a feeling I might have read it a very long time ago , but it'll be handy to have a copy in the bookshelf :-)
Heh heh , yeh , those Lucas electrics , thankfully the Japanese came along in the 1960s and showed the world how they should be made .
Cheers John
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Post by finiteparts on Jul 27, 2014 12:05:02 GMT -5
I hadn't even thought about buying directly from them...good to know! I have to commend Rolls for taking pride in what they have accomplished. I know all the big turbine companies have similar pride, but the fact that the Rolls guys get together and publish such nice works on the development of their technologies is really nice. When I got that Norbye book, I thought it might be kind of cheesey because it was only like $4 used...but it is packed full of great stuff! I was shocked...it was so cheap, I bought a second copy to keep at work so I could whip it out and show some of my fellow engineers things that they had never seen being so focused on industrial or aircraft gas turbines. For all those who would like to see more of the TJ-90 engine, here is a video of the TPR80 turboprop that uses the Sundstrand TJ90 as its core. www.youtube.com/watch?v=C9F4-GZlji8Note that for the 80-95 shp design power, the free turbine wheel is quite compact! These guys do some really beautiful work...and I REALLY like the modular core section arrangement that they have there. John sent a link a while ago for a nice technical review of their turboprop engine that can be found here: www.dtic.mil/dtic/tr/fulltext/u2/a273595.pdfM-Dot is no longer around because it merged with another company into Azmark Aero Systems...you can see the tech sheet for the TPR60 there...a 60 hp version of the TPR80.... www.azmark.aero/Enjoy, Chris
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Post by racket on Aug 10, 2014 21:50:11 GMT -5
Hi Chris Just received my copy of the Norbye book , yep , an excellent book to have , thanks again for the Link :-) I started having a bit of a flick through and thought , these pics look familiar, so dug out some photocopied pages I've had for 20 years , and sure enough the page numbers on the copies were the same as the book . The book is much more interesting now that I have a better understanding of what I'm looking at, 20 years ago I was struggling even to understand the basic concepts , now I can appreciate the content . For any of the other Members here on JATO , if you want a really good text ,take Chris' advice and get a copy www.amazon.com/Gas-Turbine-Engine-Development-Applications/dp/0801957532/ref=sr_1_2?s=books&ie=UTF8&qid=1406425115&sr=1-2&keywords=automotive%20gas%20turbines&tag=viglink20248-20Now back to find a sunny spot out of the wind and have a good read :-) Cheers John
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Post by finiteparts on Aug 12, 2014 20:56:01 GMT -5
Glad to hear it John. I know exactly what you mean about the old xerox copies! In my days back working on my undergraduate degree, I would spend so much time in the library xeroxing bits of books that promised to be helpful as opposed to doing the homework that I should have been doing! haha! As I find those old xerox copies now, I try to go find the book on Amazon to add to my collection. Unfortunately, sometimes you find the "old standards" often are worth more than the rotors for our engines and it makes it hard to shell out that much money for a book. So sometimes I guess the xerox copies will have to do! Mellor's book is one of those that is nearly impossible to find now-a-days. Even when you can find it, it is going for like $400!!! (http://www.amazon.com/Design-Turbine-Combustors-Combustion-Treatise/dp/0124900550/ref=sr_1_3?s=books&ie=UTF8&qid=1407894541&sr=1-3&keywords=Design+of+Modern+Turbine+Combustors)
But yes...I highly encourage our fellow engine builders to go out an get this book...especially when there are copies for under $5!!! I am not sure about the $97 new price though...seems a bit much.
~ Chris
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Post by racket on Aug 12, 2014 22:34:25 GMT -5
Hi Chris
LOL........I spent up big and bought a $25 copy , and then about the same to get it sent here to Oz , but well worth it ,thanks again for the Link :-)
Cheers John
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Post by finiteparts on Sept 7, 2014 13:48:58 GMT -5
So I finally got around to tearing down a T62-11 core that I have had sitting for a while. It had some damage to the combustor casing and damaged aft bearing, but I thought it might be a cool to see how Solar approached the small, cheap turbine engine. Once I got the combustor apart, I thought that I would share some pictures so that everyone could see some of the neat engineering they put into it. It is such a simple design, it might be a good one to emulate when building a homebuilt engine. So the first picture shows the cross sectional view of the T62-11 core engine: Then there is an image of the end of the combustion chamber (CC) nearest the exhaust end of the engine. Notice that the inner and outer CC liners are separate parts from the domed end piece. They are held together with the welded strut pieces. So there is a annular gap formed around either side of the domed end piece (as can be seen in cross section). This seems like a simple way for the homebuilder to approach this same problem. A close up of one of those struts...you can see the gaps formed... Now here is a "forward" end view (end towards the compressor side). Note the relatively large dilution holes and the vaporizer inlets. The vaporizer inlets are upstream (airflow is from right to left in this photo) of the dilution holes, so they see a "better" static pressure feed. In fact, you can see they were trying to take advantage of some of the airflow's total pressure by doing the scarf cut on the vaporizer inlet to "help" the flow turn in and capture some of the total pressure. Since, only the small cooling flow for the NGVs has been bled off prior to this, they are essentially feeding the vaporizers with the best possible static pressure, maximizing the flow in them. I really like this design! Here is a side view of the vaporizer inlet, with flow again from the right side to the left. This shows a "repaired" vaporizer. The other ones are just resistance welded in, this one shows the tig welded repair. Here you can see the "aft" end of the CC, and the little "hold-offs" that help to locate the domed end plate and maintain the annular gap. Another view of the "aft" end...notice the crimped end that slides into the turbine NGV section. Again, this seems like a nice simple thing for the homebuilder to "use". Also note, the holes shown on the inside liner sheet are just forward of the endplate. They are the only holes in the inside CC liner. The back plate is different than the one shown above in the engine cross section. Here is a close-up of one of the large dilution holes. You can see how they plunge the one side to aid in getting the dilution jet down into the main gas flow. So I did some reading on the T62 and found a nice report I had stashed away on it's design. The report reference is: "DEVELOPMENT OF A SMALL SINGLE- AND TWO-SHAFT GAS TURBINE FOR MILITARY APPLICATIONS", Petrie, K. (P. Engineer, Experimental Group, Solar), Proceedings of the Institution of Mechanical Engineers 1964, Vol 179, pp. 343-364. pme.sagepub.com/content/179/1/343The material the combustor is made from is 321 stainless, which should be good news to the homebuilder because 321 SS is relatively cheap compared to the nickel allloys (McMaster Carr has plenty to choose from) and it is nice to work with in both weldability and machinability. The NGV section and the turbine wheel casting are made form A286, which is a bit more pricey. The design of the engine for a military application called for it to be able to burn leaded fuels, which caused problems with the durability of the vaporizer tubes, and led them to test out all sorts of materials like Hastelloy X, Inconels, Stellites, etc...but they finally used an N-155 with an aluminized coating. We shouldn't have such issues and 321 SS should be good for our uses. The requirements for the engine to operate at -65F conditions really hurt the vaporizer combustor which led to the development of a can style CC...But I think most of us will not be running is such conditions so we should be fine with a vaporizer CC. There is a really interesting section were they discuss the compressor diffuser development. They describe four designs, three vaned and one vaneless. The three vaned diffusers have inlet angles varying from 10.7 to 12.8 to 15 degrees and plot of the compressor maps overlayed on each other shows that as the inlet vane angle is reduced, the peak pressure ratio at a given mass flow is increased. The vaneless diffuser shows a much larger flow rate capability, (mass flow number = 0.35-ish at 100% speed), were the vaned diffuser with the highest PR is only capable of flowing a massflow number of 0.21 at 100% speed. But, the pressure ratio of the vaned diffuser is near 3.25 while the vaneless is barely at 2.75 at 100% speed. Additionally, the vane diffusers are capable of stable operation at 105% speed with PR around 3.75. So that is a great illustration of why you choose a vaned diffuser or a vaneless diffuser...do you want to have the highest PR possible, but a reduced range on the compressor mass flowrate or can you take less PR for being able to flow more mass? Finally, some operational numbers that I thought were neat. The engine was contractually designed for 55 shp at a SFC of 1.28 lbsfuel/shp*hr and 1.21 lbm/s airflow at PR = 3.2...this was met with a turbine inlet temperature of 1300F. But they were able to uprate the engine to TIT of 1450F, PR = 3.3, airflow = 1.34 lbm/s and SFC = 1.17 getting 68 shp with no change in hardware. Further development work with better compressor and turbine matching got them to 115 shp and SFC = 1.0 lbsfuel/shp*hr. I hope this gives some of you ideas for your next combustor design. ~ Chris
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hurdman
Member
Joined: July 2014
Posts: 11
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Post by hurdman on Sept 11, 2014 10:04:07 GMT -5
Hello Chris, I really enjoy the information you have posted about the development of small turbine engines. Its interesting to compare/create "carry-over" design details between the professionally manufactured engines and our DIY efforts.
With that being said, could you take a few measurements of the T62 core and post them. There is no rush, just mental gymnastics: 1. Compressor inducer diameter 2. FT OD 3. FT ID 4. Inner FT to dome annulus gap 5. Outer FT to dome annulus gap 6. Diameter of the 18 holes in rear dome piece 7. Number and ID of Evaporator tubes 8. Number and diameter of large dilution holes in outer FT 9. Number and diameter of small holes in inner FT 10. Distance from end of evaporator tube to rear dome inner surface
Thanks in advance Chris, and thanks for the small engine postings.
Danny AKA hurdman
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Post by pitciblackscotland on Sept 11, 2014 12:57:13 GMT -5
Hi Chris, Just want to say thank you for sharing all this information you put on this site as it is time consuming. I have two rare GTC20-1 Turbines that i will soon get them up and running and then i would like to examine the combustor design. I did start a thread on them some time ago you can check them out see what you think. Cheers, Mark..
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Post by finiteparts on Sept 14, 2014 13:11:09 GMT -5
Hi Danny,
Here are the dimensions, as best as I can measure them,
1. Compressor inducer tip diameter = 4.225 inch , inducer hub diameter = 1.815 inch, Exducer diameter = 6.25 inch, exducer passage height = .385 inch 2. FT OD = 10.5 inches (casing ID = 11 inches) 3. FT ID = 4.675 inches 4. Inner FT to dome annulus gap ...can't get into it to measure..looks like about 0.125 inch 5. Outer FT to dome annulus gap ...Again, can't get into it to measure it...it looks larger than the outer gap 6. Diameter of the 18 holes in rear dome piece = 0.150 inch 7. Number and ID of Evaporator tubes = 0.5 inch, 0.040 wall X 6 tubes 8. Number and diameter of large dilution holes in outer FT = 0.690 inch X 12 holes 9. Number and diameter of small holes in inner FT = 0.25 X 12 holes 10. Distance from end of evaporator tube to rear dome inner surface = can't get in there to measure, but looks like about 0.75 inch...overall combustor length is 5.75 inches.
Some additional dimensions in case you need them...
NGV passage height = 0.415 inch NGV passage throat width ~ 0.440 inches x 17 passages (Turbine has 12 blades, there there should not be any resonance due to blade passing frequencies) Turbine exducer tip diameter = 4.210 inches Turbine exducer hub diameter = 0.950 inches Exhaust exit diameter = 5.5 inch Exhaust passage length = 8 inches (so the expansion half angle is = 4.6 degrees) Passage in outer casing for vaporizer injector tube = 0.075 inch...the the vaporizer injector outer diameter is below this.
Hope that helps!
~ Chris
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