Recent content by dan-g

so i can't just put the results down to magic!? all magic aside then can anything be concluded from the test?? i would imagine that the error is with the air just as it exits the pipe but seeing as i only have to compare the rough with the smooth would the error not be common to both cases? the...

i'm slightly confused with that though, doesn't that give an equation with two variables then??

well it turns out that for some strange reason the wind tunnel sucks instead of blows! iv new results that arent affected by flow around the pipe inlet is the measurement taken furthest from the fan/source smooth pipe inlet velocity outlet velocity...

where c=?? constant or what??

just doing a bit more on this and... dynamic pressure=1/2*ρv^2 @10m/s...=1/2*1.29*10^2 ...=64.5 64.5-36.5997=27.9003...(36.5997 is the pressure drop due to friction) 27.9003=1/2*1.29*v^2 0.645v^2=27.9003 v^2=43.2567 v=√43.2567 v=6.57695m/s does that not suggest a drop in velocity...

so a pressure drop is what I'm looking for then(which will show as a velocity increase?), to prove that the rough walls restrict flow or am i picking that up wrong? the system should be fairly close to completely isothermal, well close enough for the test that i could neglect it for now. it...

it was only possible to measure the velocity with what i had in college but the calculations are all based on pressure drop, sorry about that!

really confused now! the purpose of the whole thing is to compare the airflow through a rough and a smooth pipe. I'm only going to compare the calculations with the calculations and the test results with test results. from my calculations above i'v got a greater pressure drop from the rougher...

right so until i can retest this i thought i'd look over the calculations, just looking for verification really smooth L=0.8m ∅=0.036m ε=0.000045m v=10m/s ρ=1.29kg/m^3 μ=0.0000198kg/ms giving reynolds number= 23454.5455 friction factor (0.316/Re^.25)=0.0255 then using...

the fan blades of the anemometer are about 40mm so you there is a problem there! havnt really got the time to get any smaller 1's as the paper has to be handed up in 4 days but i think i'l retest it with a few alterations made to measure just the flow through the pipe, thanks for the help, i'l...

the air is measured using a anemometer similar to ...http://www.ebay.co.uk/itm/Advanced-Digital-Handheld-Wind-Speed-Meter-Anemometer-Beaufort-Scale-vwlocity-/170976656131?pt=UK_Sound_Vision_Other&hash=item27cf00bb03 i know there's some discrepancies in the results due some air flowing around...

from the experiment these are the results that i got, which shows that there a clear velocity drop though?? smooth pipe inlet velocity(m/s) outlet velocity(m/s) velocity drop(m/s) 4.03 ...... 2.07 ...... 1.97 5.63 ...... 2.4 ...... 3.23 7.3...

would that be true for an open ended pipe though? as the inlet is closer to the source of the air

bit more info might help! pipe is 800mm long, 36mm diameter and absolute roughness is 0.000045m using wind speed entering the pipe of 10m/s, what is the wind speed exiting the pipe?? so far i'v got reynolds no to be 23454.5455, friction factor as 0.0207 and frictional head loss to be 2.34745m...

well I'm trying to compare the velocity difference of say the smooth pipe in the wind tunnel to a theoretical velocity difference of the smooth pipe if you get me?!