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Post by racket on Nov 22, 2022 14:51:59 GMT -5
Thats hardly the "smallest possible combustion chamber " :-(
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notjet
Junior Member
switzerland sure doesnt like selling large piping in my area ._.
Joined: October 2022
Posts: 54
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Post by notjet on Nov 22, 2022 15:15:01 GMT -5
Hi John, yeah sorry about that, i had some weird thought that an annular chamber would be realy fat but that isnt true right? I did some measurements on the moped frame and found out that 30cm lenght isnt a problem but i need to get it skinnier to about 130mm total combustion chamber diameter if i want it all to fit and still look good :/
Cheers, Neo
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Post by racket on Nov 22, 2022 16:05:40 GMT -5
Hi Neo
With a 50 mm inducer , the flametube cross sectional area needs to be 5890 sq mms or 87 mm dia , even with a 40 mm "hole" to create an annular flametube , the OD of the annular flametube only needs to be ~96 mm dia , add on 10 mm per side for airflow , and we have an outer can ID of 116 mm.
If we have a annular flametube of 40 mm ID X 96 mm OD = 56 mm for the two sides, so only 28 mm wide annulus ring , which will only require ~100 mm length at most
With say 10 evap tubes to get good coverage of fuel , you now have a "small" combustor
Cheers John
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notjet
Junior Member
switzerland sure doesnt like selling large piping in my area ._.
Joined: October 2022
Posts: 54
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Post by notjet on Nov 22, 2022 16:10:19 GMT -5
Hi John, I just calculated the annular "ring" berfore coming online and came to that conclusion too, i dont know why i didnt do that earlier but thanks for boosting my confidence and confirming that lol, ill go draw a proper combustor now that hopefully wont have much issues with the design...
Cheers and Thx, Neo
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notjet
Junior Member
switzerland sure doesnt like selling large piping in my area ._.
Joined: October 2022
Posts: 54
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Post by notjet on Nov 25, 2022 5:43:41 GMT -5
I certainly hope my turbo will arrive soon
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notjet
Junior Member
switzerland sure doesnt like selling large piping in my area ._.
Joined: October 2022
Posts: 54
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Post by notjet on Nov 26, 2022 10:45:11 GMT -5
Hi John, is it a problem if the inner tube cross section area is greater than 1.5x the area of the inner tube holes?
Cheers, Neo
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Post by racket on Nov 26, 2022 15:36:53 GMT -5
No , but if its bigger then the OD of the FT will be bigger and the outer can as well , you're trying to get the smallest possible
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notjet
Junior Member
switzerland sure doesnt like selling large piping in my area ._.
Joined: October 2022
Posts: 54
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Post by notjet on Nov 27, 2022 16:15:01 GMT -5
Hi John, Here is my new ft design, please ignore the calculations since im not the brightest but you may want to look at the marked numbers also there are just 10 holes at the top which are offset from the middle of the ring closer to the inner tube primary holes...
Cheers, Neo
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Post by racket on Nov 28, 2022 19:40:54 GMT -5
Hi Neo
I'm having difficulties understanding your drawing :-(
Could you just write out the holes sizes and number etc etc
Cheers John
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notjet
Junior Member
switzerland sure doesnt like selling large piping in my area ._.
Joined: October 2022
Posts: 54
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Post by notjet on Nov 29, 2022 15:55:20 GMT -5
Hi John,
Here is the hole data:
Outer tube: Primary: 30x 5mm Secondary: 10x 7mm Tertiary: 10x 11mm
Inner tube: Primary: 10x 3.6mm
Secondary: 10x 3.2mm
Tertiary: 10x 5mm Top: 10x 5mm
Question: should the area of the evap tubes also be calculated with the hole area or in some different way?
Here are the Ft sizes: ID: 22mm OD: 96mm lenght: 90mm Primary: 7mm from top and second row 16mm from top Secondary: 35mm from top
Tertiary: 75mm from top taper is 30mm long and tapers into 65mm seen from side
Cheers, Neo
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notjet
Junior Member
switzerland sure doesnt like selling large piping in my area ._.
Joined: October 2022
Posts: 54
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Post by notjet on Nov 29, 2022 16:30:29 GMT -5
I forgot to mention these numbers are for a 54mm inducer, as my hx35 just arrived
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Post by racket on Nov 29, 2022 16:54:43 GMT -5
Hi Neo
Thanks for that , I'll have a look at them and get back to you :-)
Cheers John
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Post by racket on Nov 30, 2022 2:52:15 GMT -5
Hi Neo
I think you need more hole area in the inner wall .
The evaporator tubes flow area needs to be included into the total Primary hole portion of overall hole area , something ~10-12% of total wall hole area for the tubes , so ~230 sq mms , or 23 sq mms/tube if 10 of them , so ~5.4 mm ID .
If we go with 30% for Primary , 54 mm inducer = 2300 sq mms , 2300 X0.3 = 687 sq mms, take off the 230 sq mms for the evap tubes , leaves 457 sq mms for Primary wall holes , I'd be splitting the areas more equally between inner and outer walls , I generally go for a bit more through the outer than the inner , 50% outer , 35% inner and the remaining 15% for the other walls , this will require a bit larger diameter for your inner/outer wall .
Cheers John
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notjet
Junior Member
switzerland sure doesnt like selling large piping in my area ._.
Joined: October 2022
Posts: 54
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Post by notjet on Dec 2, 2022 17:13:04 GMT -5
Hi John,
Sorry for the late reply, i will do the calculations and make a proper drawing (hopefully) of the new FT, i was wondering tho, if on the bottom wall (turbine side of ft) there are the 10 evap tube holes, should i put the 15% inducer area holes all on the op or put sone small ones between the evap tubes,
Cheers, Neo
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Post by racket on Dec 2, 2022 23:20:50 GMT -5
Hi Neo
If it looks right , it is :-)
Cheers John
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