ganuganu
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Joined: November 2013
Posts: 30 
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Post by ganuganu on Sept 27, 2014 12:29:32 GMT -5
I have an important question here. If we are constructing a new turbocharger usually analysis for critical speed will be done and max rpm will be fixed. How about if iam buying a second hand turbocharger and use it as gas turbine, how will i know the critical speed of that turbocharger?? Please help me.
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Post by racket on Sept 27, 2014 16:12:36 GMT -5
Hi Don't worry about critical speed , turbochargers have bearings which dampen out the problem . As for maximum rpm , keep the tip speed of the larger wheel (generally the compressor wheel) below 1450 feet/second , if you use Jetspecs www.nuclearprojects.com/jetspecs/flametube.php it will calculate for you . Cheers John |
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ganuganu
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Joined: November 2013
Posts: 30
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Post by ganuganu on Sept 29, 2014 9:06:55 GMT -5
Thanks for the quick response sir. This question is out of curiosity, the link which you provided to calculate the FT dimensions how much loss(pressure) does it produce. Usually reference say that 4 to 10% is the allowable limit does this link actually comes under this limit.
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Post by racket on Sept 29, 2014 15:58:06 GMT -5
Yes it should , pressure loss generally goes up when the flametube is "small" , Jetspecs produces a generously proportioned combustor , just make sure the flametube holes are bellmouthed
Cheers
John
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ganuganu
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Joined: November 2013
Posts: 30
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Post by ganuganu on Sept 30, 2014 10:48:55 GMT -5
Yes it should , pressure loss generally goes up when the flametube is "small" , Jetspecs produces a generously proportioned combustor , just make sure the flametube holes are bellmouthed Cheers John Usually we will select a particular design point from the compressor map and find the corresponding PR and Mass flow then we will calculate the FT size but here it is using impeller eye diameter to calculate FT size. My question is, is it calculating the mass flow using the hub to tip ratio of the impeller eye with corresponding velocity and density. |
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Post by racket on Sept 30, 2014 16:03:27 GMT -5
Hi
Jetspecs tries to cover all turbos irrespective of design , a very difficult job , hence it can only be a rough guide to producing a working engine , but it should and does produce working engines, the fine tuning of the engine then needs to be done using trial an error methods due in most cases to a lack of compressor maps for most turbochargers , especially older models which due to their inexpensive nature are used by DIY builders who use Jetspecs to make a jet engine out of .
Jetspecs uses the area of the inducer, including the hub, to determine the total hole area of the flametube in a ~30% primary ,~20% secondary and ~ 50% tertiary ratio , the total hole area should be roughly the same as the inducer area .
As for mass flow , most turbos flow between 11 and 12 lbs/minute/square inch of inducer , again only a rough guide as other engine components can vary this one way or the other .
Cheers
John
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ganuganu
Member
Joined: November 2013
Posts: 30
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Post by ganuganu on Oct 1, 2014 1:44:50 GMT -5
In fact designing a combustion camber is an art rather than science. Thanks for your quick reply sir.
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ganuganu
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Joined: November 2013
Posts: 30
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Post by ganuganu on Oct 17, 2014 3:01:20 GMT -5
After a search in bangalore(India) finally i found a dealer in second hand turbochargers. This is the first time iam going to buy a turbocharger i need some guidance in reviewing the turbocharger. Dealer said that he got Holset HX25 cost 8000 INR, is a second hand turbocharger worth this money. I really dont have an idea about the cost of new HX25 product. Someone please help me.
Thank you
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Post by finiteparts on Oct 18, 2014 15:28:02 GMT -5
Hi ganuganu,
I converted that to US dollars and $130 isn't bad for a Holset turbo in good shape. The HX25 is kind of small. I wasn't able to find dimensions on the compressor and turbine sizes...can you measure them? Can you check to make sure that the impellers look to be in good shape and no signs of rub?
If you could snap some pictures, it might be easier for everyone on here to comment on condition.
~ Chris
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Post by racket on Oct 18, 2014 18:41:49 GMT -5
Just make sure the area of the turbine wheel exducer ( outlet) is at least 25% bigger the area of the compressor wheel inducer (inlet) otherwise the turbine stage will be too small to flow the output of the compressor wheel when the turbo is converted into a gas turbine .
A lot of small turbochargers are designed to have "undersized" turbine stages as that configuration better suits their use on an IC engine .
Cheers
John
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ganuganu
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Joined: November 2013
Posts: 30
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Post by ganuganu on Oct 19, 2014 22:56:03 GMT -5
finiteparts thanks for your reply, i will surely snap some pic and post it here. This week saturday iam going to meet the dealer for the turbo. racket ya sure i will check for it.
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ganuganu
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Joined: November 2013
Posts: 30
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Post by ganuganu on Mar 21, 2015 9:20:11 GMT -5
Sorry for updating after long time, i was involved in companies steam turbine project. Today i went to a place in bangalore where we can find all kinds of second hand automobile components and i found a toyota innova turbocharger used for 100.6hp engine. It was pretty small but unfortunately iam unable to find the compressor map for it. If anyone has please share it with me. Thank you. Here is the pic of the turbocharger. Note: The turbocharger on which toyota is written on it. PLease follow the link below. postimg.org/image/uii1sb1i1/ |
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Post by madpatty on Mar 21, 2015 11:59:39 GMT -5
Hi Ganuganu,
Rs 8000 is too much for such a small turbocharger....you can get a holset HX35 brand new CHRA in about 10000 bucks...then why to go for a second hand and that too a smaller turbo when you are already spending this much....
Cheers,
Patty
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ganuganu
Member
Joined: November 2013
Posts: 30
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Post by ganuganu on Mar 21, 2015 12:56:14 GMT -5
Hi Ganuganu, Rs 8000 is too much for such a small turbocharger....you can get a holset HX35 brand new CHRA in about 10000 bucks...then why to go for a second hand and that too a smaller turbo when you are already spending this much.... Cheers, Patty Not for 8000 I asked it for 4000. Seriously hx35 is 10000 inr only!!!!! Can you please share me the link... |
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Post by madpatty on Mar 21, 2015 13:00:04 GMT -5
LOL...links not work here in India...
You need to find a local holset service centre(i got one in my city)...you can find one near you from their website....
Almost 10000 bucks for the core and some 1000-1500 for the compressor and turbine housings....turbocharger is ready...
Cheers,
Patty
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