|
|
Post by stoffe64 on Apr 21, 2011 11:05:07 GMT -5
|
|
|
|
Post by racket on Apr 21, 2011 17:08:19 GMT -5
|
|
|
|
Post by ernie wrenn on Apr 25, 2011 8:31:37 GMT -5
Racket
How about checking my math.
96 holes
.075 drill size
I come up with a flow area of .40176
I need to max out the .500 tubing with a .040 wall thickness. ...leaves .0812 short?
Plessure on AB pump set at 1200 psi backflow popet.
Feeding with a #10 jic from pump to #10 T.. splitting into 2 #10 lines going into the lollypop on each side for feeding the ring.
Any idea of flow numbers using 50/50 gas and diesel fuel.
Can't get the math 101 working today.
Ernie
|
|
|
|
Post by ernie wrenn on Apr 25, 2011 19:59:51 GMT -5
Thanks... I was close, but got lost in the numbers.
Ernie
|
|
|
|
Post by racket on Apr 25, 2011 20:48:46 GMT -5
Hi Ernie
Gunna do this from basics as somethings not making sense here :-(( .
Your engine flows ~50 lbs/sec -3,000 lbs/min , therefore you need a total of ~200 lbs/min of fuel , 50 lbs to the flametube, 150lbs/min to the A/B at an overall 15:1 A/F ratio
Your 96 holes will flow at ~60% effective area due to their sharp edge inside the plumbing .
Velocity at 1200 psi is ~400 ft/sec
96 holes at 0.075" dia = 0.4241 sq ins or ~a 3/4" dia hole
Therefore ~0.72 cubic ft per second or 43.2 cu ft/min or ~2160 lbs/min , way too much , lets go back to say 100psi , flow generally at square root of pressure so roughly 34.6 :10 ratio , still way too much at 625 lbs/min , 4 times too much , pressure needs to be super low , lets go to 10psi , sq root 10 = 3.16 , or a 10:3.16 ratio , still too much , bugger , you're gunna need a very low pressure .
When I did flow tests on my kart injectors , using 4 X 1/32"- 0.032" dia holes and 5 psi fuel pressure the 4 holes flowed 0.8 litres/min or 0.2 litres/min / hole , 96 of those 1/32" dia holes would have flowed 19 litres/min - 33 lbs/min of kero , if they were 0.075" holes that would be ~110 litres/min or ~190 lbs/min of kero ................still too much for you .
The AiReseach turbojet of c 1978 used 8 X 0.035" injection orifaces in its A/B flowing up to 2.5 lbs/sec of air , or ~5% of your engines air flow , therefore you'd only need 160 X 0.035" dia injector holes running pressures between 25 -50 psi above static gas pressures in your A/B , these should only be ~10-12 psig . ...............so a max fuel pressure of perhaps 60 psi with 0.035" oriface , with your 0.075 holes it'll be a max fuel pressure somewhere around 20psig, lotsa variables that could increase or decrease that pressure , but not by very much .
Hope this helps
Cheers
John
|
|
