Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 16, 2016 4:22:16 GMT -5
thanks John.
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 16, 2016 4:43:02 GMT -5
hi John, i have decided to change the diameter of the whole engine just to be on the safest side so as to have more room for any correction in the future. from your comment about my diffuser being set at a very low angle at their leading edge i will need your help in correcting them in my new build. but please before then i will like you to look at the drawing of the whole engine and see if there is anything odd. thanks.
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 16, 2016 5:11:48 GMT -5
DETAIL ON THE NEW CKS-01 ENGINE CASING external diameter 227mm internal diameter 224mm wall thickness 1.5 COMPRESSOR Inducer diameter 91mm exducer diameter 135mm tips height 8mm
TURBINE inducer 94mm exducer 115mm tips height 16mm the new turbine blade i bought happened to be 3mm bigger in inducer diameter. NEW combustor outer wall 202mm
inner wall 115 mm
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 16, 2016 5:14:42 GMT -5
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 16, 2016 5:39:45 GMT -5
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 16, 2016 5:48:06 GMT -5
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 16, 2016 5:55:14 GMT -5
the clearance between the shaft and the combustor inner wall is 15mm.
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 16, 2016 5:59:11 GMT -5
if there are more details you need to know you let me know SIR. looking forward to your response, thanks.
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Post by racket on May 17, 2016 1:15:46 GMT -5
Yep , things look reasonable.
Your comp recess in the diffuser wall will need to be 1.5 millimetre bigger in diameter than the comp exducer, and your NGV vanes could do with being tapered so that theres not such an abrupt increase in area downstream of the their ends.
Actual comp diffuser angles etc etc will need to be calculated by you taking into account the exducer swept back angle , tip speed at your desired rpm , projected mass flow etc etc ...
The same with the NGV angles and throat areas which will depend on your temperatures, pressures etc etc ....
Lotsa unknowns that you'll have to make assumptions about .
Cheers John
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 17, 2016 6:29:18 GMT -5
thanks for the useful information. I have taken note of the comp recess in the diffuser wall to be 1.5 bigger in diameter, i understand its for heat expansion and probably bearing play during spool up.
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 17, 2016 6:39:33 GMT -5
but the diffuser angle etc/ NGV angle are what i really need your help on, in this build your are the brain then i will be the muscle then in my next build i will have to pick datas from here as my reference. assumptions? lol that's my number one challenge. thanks.
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Post by racket on May 17, 2016 17:41:48 GMT -5
Hi Chuksy
I don't like providing detailed data unless I know exactly what I'm commenting on , without handling the compressor and measuring all its parameters , the same with the turbine wheel , and without knowing the diffuser and NGV will be constructed to the highest standard exactly to my figures its only a waste of my time doing them ..............I've been misled too many times over the years with guys telling me one thing and doing another .
I would prefer that you do the designing and I'll then check it, that way I know what you intend building .
If you haven't already got the Kamp books I'd suggest you purchase it and start to learn the maths required to build an engine , there are simply too many components in an engine that must match each other , and from this distance and with only a few pics to go from, its virtually impossible for me to do the designing with any degree of competency.
Having seen your level of machining ability , I don't think you'll have any problems with the design theory
Cheers John
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Chuks
Senior Member
Joined: August 2015
Posts: 497
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Post by Chuks on May 19, 2016 9:31:37 GMT -5
thanks John, i think i will need to just machine others part while looking at means to understand some factors needed to build cut the ngv and the diffuser. meanwhile, can you tell me what clearance i need to maintain between the compressor and the compressor housing?
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Post by racket on May 19, 2016 22:58:57 GMT -5
Aim for ~ 0.012"- 0.3mm axial clearance at the exducer , and 0.015" - 0.35 mm radial clearance at the inducer , because of the clearances in the journal bearings we can't reduce the clearance to more ideal levels
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Post by racket on May 21, 2016 22:23:42 GMT -5
Hi Chuksy
I've been doing some numbers on your compressor stage and it looks like you'll need to "taper" the vaneless space between comp exducer and the leading edge of the diffuser vanes , this can be done by "burying" the comp wheel deeper into the comp cover and continuing the "taper" thats usual for the shroud at the exducer out to the 155mm diameter , the diffuser vane heights only need to be ~6.5 mm , not the 8 mm tip height of the comp wheel .
By tapering the 10 mm wide vaneless space , this replicates what is normally done with the turbocharger comp cover, the reduction in axial height forces the air to a greater radius quicker, increasing/maintaining the radial component of the air velocity which would normally drop off as the air slowed due to the increase in radial distance with consequential compression taking place .
Due to the higher radial speed caused by the narrowing of the flow passageway , your leading edge of the diffuser vanes will be experiencing airflow at a ~21-22 degree tangent , this then makes it easier to design your diffuser vanes to obtain the desired throat area at ~160 mm dia ..............the diffuser throat area is CRITICAL , so some juggling of diffuser vane number and/or width is required to obtain that throat area .
Cheers John
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