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Post by madpatty on Aug 25, 2021 21:03:26 GMT -5
Hi Chris. Those two pics are of the same blade. The stains are some oil leaking past the seal and getting on the hot wheel post run. Here are some more pictures. Thanks
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Post by madpatty on Aug 25, 2021 14:56:53 GMT -5
Hi All. So this happened when I tested my engine last. I saw a small pin hole crack in the turbine inducer after I disassembled the engine. Also the turbine inducer tips have “grown” radially by atleast 2 mm as I had a hard time pulling the turbine out of the NGV top plate. I don’t know if it was there before or it’s a result of creep. The turbine wasn’t even run to full rpm, max. Turbine tip speed was about 1450ft/s and temperatures were surely not high. I have seen much worse colours on turbine wheel at much higher temperature. Has anyone seen this before, or maybe it was just a bad quality wheel. Regards. Patty
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Post by madpatty on Aug 22, 2021 8:53:26 GMT -5
Not sunflower or vegetable oil BUT I have tried Castor oil as the fuel. More of a Castor oil and biodiesel blend.
It was denser than normal diesel. I don’t remember any exceptional running characteristics or any issues.
Regards.
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Post by madpatty on Aug 15, 2021 4:45:54 GMT -5
That’s a beautiful beast of a machine you are building John. The bare metal look is almost unbeatable.
Cheers.
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Post by madpatty on Aug 9, 2021 7:38:54 GMT -5
Hello All. I found this Jaquet automotive turbocharger speed sensor spec sheet and thought it would be helpful to share it here. The document lists various types of turbocharger speed sensors used in the automotive industry and the tech behind them. www.vikacontrols.com.br/wp-content/uploads/produtos/catalogos/Aplicacoes_Jaquet_-_Turbochargers.pdfJaquet is the leading brand for many OEM applications including Garrett and most probably Holset and BorgWarner as well. The speed sensor that you can buy directly from Garrett is a “Jaquet dSE 0603.02 THV | Hermes 3.5” that uses passive eddy current tech to count the blades. Cummins probably uses their “Artemis Variable Reluctance” sensors that senses a flat machined on the turbine shaft. BorgWarner probably uses one of their Hermes passive eddy current type that again counts the blades. Cheers.
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Post by madpatty on Jul 19, 2021 18:46:11 GMT -5
Hi racket. Continuing the axial vs radial turbine discussion here. I just rechecked my calculations and found I did use 80% as overall stage efficiency for axial wheel as wheel as well. Some preliminary calculations for a 99Kg thrust engine showed it needs a larger ~150-160mm turbine inducer with a much steep 28 degrees of NGV angle and atleast 130mm of turbine exducer. Are these similar to what you are seeing with your manned aircraft engine Whereas commercially available engines in this category are available to get 100kg thrust out with just ~140-145mm turbine wheels, which is quite impressive. Thanks.
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Post by madpatty on Jul 19, 2021 17:48:26 GMT -5
Hi Patty It can only be an efficiency thing if flow areas are the same , our radial stages can be a lot more efficient than 70% , I generally work on 80% when using a NGV stator. Cheers John Thanks Racket. Sorry I realized I posted it in the Andy's thread whereas had to post it in my thread. But still thanks for the reply here.
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Post by madpatty on Jul 6, 2021 10:22:23 GMT -5
Hello Gents. Out of curiosity I was reading the literature available and playing around with possible compressor diffuser vane designs and had this question came lingering up in my mind. Why can’t we design something like this- Sorry for the crapy drawing but this gives the idea. The flow at the diffuser outlet has significant swirl component and follows the path shown by yellow line and we need to get rid of that swirl somehow. Why can’t we modify the shape of the vanes(shown by green colour) so that the swirl gets reduced at the diffuser outlet (new air path shown in red). Am I missing something? BUT I have yet to see a diffuser with these shaped vanes. I know the axial vanes do this but this way we can get away without them this reducing the overall thickness of the diffuser especially for engines with already restricted lengths due to standard turbo shafts. Regards. Patty
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Post by madpatty on Jun 22, 2021 9:33:49 GMT -5
Hi Joe. I am sure we can use spray nozzles in annular combustors. SR-30 educational jet engine uses 'I think' 6 spray nozzles and its a smaller engine than what you are targeting. I am not able to add the picture but here's the link to their website- www.turbinetechnologies.com/educational-lab-products/turbojet-engine-labYou can see their engine's cut away. I think no one wants added complexity over the proven EVAP design but again getting away with using a spray nozzles will be better than getting those flimsy needles blocked or broken off every now or then. Brazing those needles is another pain. I like more "industrial" design where you just replace the part(nozzle) if it stops working due to some reason. I think all the R&D that has been put into the RC turbines, the fuel manifold and vaporizer tubes is the only thing that has been left behind. Regards. Patty
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Post by madpatty on Jun 21, 2021 22:00:33 GMT -5
Looks like #73 drill bit, so .024" hole. not sure the hole size on the "racketjectors"? Also I took the injector apart, it's 1/8"npt, and has a nice screen to keep crud out of the hole. I think this could be a very viable injector. The mass of it should make it pretty sturdy for the job as well. Hi Joe. It would be interesting to see this nozzle as a viable injector. There are Stainless versions also available out there just in case you wanna use a similar thing. I myself want to get rid of these flimsy needles from my engines and am on a lookout for a suitable fuel nozzle for our engines with annular combustors. Cheers. Patty
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Post by madpatty on May 26, 2021 9:25:46 GMT -5
It is possible to "bleed and burn" , but the thrust produced isn't as great as expected due to the fact we need to expend greater amounts of pressure drop to get less and less increase in jet nozzle velocity , unfortunately thrust is simply mass times velocity , whereas the kinetic energy has a "velocity squared" component , kinetic energy in the exhaust goes up faster than the velocity increase. This is what you invisage www.youtube.com/watch?v=4EZJkwWHQ8MCheers John Or this- youtu.be/hCwz7mnymr4Cheers.
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Post by madpatty on May 16, 2021 7:41:36 GMT -5
Here is the x-section.. Thanks Chris. By looking at the actual part I have, the shaft that transmits torque between the turbine and compressor (where torque is more) is too small compared to the curvic coupled shafts between the compressors and between the turbines. I think rotor dynamics may have to do something with this. Since I have both ends of the turbine capable of being adapted to take a gear for power transmission I was thinking which side to use for power turbine application. Thanks
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Post by madpatty on May 15, 2021 12:45:48 GMT -5
Hi Chris.
Thanks for that. I was gonna buy both but chose to buy just one of them.
Do you have a cut Section view of that engine or a picture. I am trying to see how this particular part fits in the engine. Will help to decide the adequate bearing arrangement for the wheel in free turbine application.
Thanks
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Post by madpatty on May 14, 2021 19:23:47 GMT -5
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Post by madpatty on May 8, 2021 6:56:41 GMT -5
Hi Racket.
This CHRA looks strikingly similar to the holset CHRAs I have worked with over the years, especially smaller HX35 and HX40 ones. Really simple and easy to replicate.
The distance between compressor and turbine is what. 170mm approx?
Cheers. Patty
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