does anybody know if we have to go to the lecture? Will they do anything if you miss it?

1/26/2006 9:26:47 PM

This is the first semester they are doing lectures. I don't know what they will do if you don't go, but the whole idea is to have half a clue what is going on in lab before you get their to make things easier, so you probably should go.

1/26/2006 10:30:17 PM

you probably dont need to go

that damn room is packed full and stuffy as shit anyway

Ill bet only about 1/2 of the people that were there last time will be there tomorrow

1/27/2006 2:52:57 AM

yeah it seemed like he was going to take attendance, but it would be really hard with that many people

1/27/2006 10:23:12 AM

i asked Tran today how he will be handling it. he will be passing around sheets individually instead of only the pad so it'll go quicker since 1 person wont have the whole list but just the select section sheet.

1/27/2006 10:55:00 AM

well that was a huge waste of my time

1/27/2006 2:07:33 PM

is there any penatly towards your grade if u dont show up

1/27/2006 2:13:37 PM

anyone in section 201, monday at 1:30? i have a question about the 6 data points from the manufacture's curve

1/27/2006 5:18:53 PM

anyone know if we have to calculate percent error between Qexp,sg=1 and Qman,sg=1 and between Qideal and Qexp? the lab guidelines mention nothing of it.

1/29/2006 12:09:18 PM

I wasn't sure about that as well. I went ahead and did it anyway just in case.

1/29/2006 3:30:24 PM

anybody know what volume each line represents?

and are we supposed to have Q in cm^3 or ft^3 or what

1/29/2006 5:14:05 PM

is anyone's Qideals really different from the Qexp values for the venturi? mine are waaaayyy different and i have no idea why. using the formula that was provided.

1/29/2006 5:38:07 PM

.069 gallons 261.193 cm^3

either one, i would say to use cm^3 though

[is anyone's Qideals really different from the Qexp values for the venturi? mine are waaaayyy different and i have no idea why. using the formula that was provided.]

if you converted everything right you should get something really small in m^3/ sec, if you convert it to cm^3/sec (Qexp is in cm^3/sec) it should be close to Qexp

1/29/2006 5:59:31 PM

yea i'm doin everythin in english units cause i figured it'd be easier. but maybe it isnt?

1/29/2006 6:06:33 PM

metric is almost always easier, that's what I would recommend

hey, the delta p value we measured was in inches of Hg

does that translate to any real unit of pressure? I'm not sure what to do with that

1/29/2006 7:17:09 PM

omg i forgot that it was mercury! holy shit that just saved my butt..thanks nerdchick

btw 1 inch Hg = 3.387 kPa

1/29/2006 7:23:21 PM

thanks man, glad I could help

1/29/2006 7:23:59 PM

okay, here's my graph for the venturi, my exp and ideal get to be way different

am I doing something wrong, or is it supposed to look like this

1/29/2006 7:37:24 PM

yea this is mine:

1/29/2006 7:59:39 PM

mine ended up looking like Nerdchick, not sure why yours look so different brianj320

1/29/2006 8:21:40 PM

yea i have no fuckin clue either

1/29/2006 8:28:48 PM

changing my pressures, this is my new graph

1/29/2006 8:35:01 PM

accordin to my TA, "The pressures recorded from the manometer in class for the veturi part are inches of water."

1/29/2006 9:07:03 PM

ohhh, so what's the conversion factor for inches of water?

I'm not sure why your values for P are so high, mine are all <100

1/29/2006 9:09:51 PM

bttt, anybody know what conversion we are supposed to use from in Hg to Pa

1/30/2006 9:11:01 PM

you need to start by using inches Hg in the deltaP=(densityHg)(gravity)(heightHg) where your inches Hg will go in the height. if you want to get your deltaP in Pascals I would convert your inches to meters, then plug metric units into the deltaP equation; deltaP=(13.6)(998 kg/m^3)(9.81 m/s^2)(mHg), 13.6 bc of the specific gravity of mercury. if you want to use english units with this equation you have to remember your gravity will cancel out because of the lbf/lbm conversion, this conversion can also screw up your flow rate calculation.

1/30/2006 9:53:40 PM

so far I've multiplied by 3.387 to get from in Hg to kPa

my Qideal is still way different than Qexp and I'm not sure what I'm doing wrong

1/30/2006 10:09:23 PM

so I found a way to get a Qideal that is very close to Qexp

The only problem is that deltap should be 1.69 kPa according to my conversion factor of 3.387, not 16.9. Something inside the square root is off by a factor of ten. But doing it this way gives me really good numbers. Does anybody see what else I might be doing wrong?

1/30/2006 10:31:22 PM

I think your problem is in your conversion from m to cm. There are only 100 cm in a m, not 1000.

1/30/2006 10:41:03 PM

>.<

thanks a lot, I've been looking at this forever and didn't spot that.

1/30/2006 10:48:53 PM

nerdchick pwnt by a n00b

1/30/2006 10:59:42 PM

stfu, n00b

1/30/2006 11:00:40 PM

man my shit came out perfect as far as i know. my experimental and ideal values are pretty much right on.

1/30/2006 11:32:02 PM

i dont see how your graphs are so far apart, mine are practicly on top of each other

2/1/2006 3:29:29 AM

Ok so I read through this whole thing and still didn't really understand how to do the conversion for delta p. Its in in per hg so what does it need to be in?

2/1/2006 12:20:15 PM

this might help

2/1/2006 12:50:18 PM

delta P is in in OF Hg and needs to be in Pascals to use with the Qideal equation.

the conversion is in the front of the fluids book, and it is:

1 in Hg = 3.387 kPa or 3387 Pa

2/1/2006 2:21:42 PM

lol this class sucks.

which e/D are we using to tabulate friction factor?

[Edited on February 3, 2006 at 11:46 AM. Reason : cause i didn't write that shit down.]

2/3/2006 11:45:34 AM

^ assume smooth pipe

2/3/2006 1:12:08 PM

who told u to assume smooth pipe? if u do the roughness/diameter u dont get 0, which is a smooth pipe.

btw, is Q supposed to be .669gal/line or .069gal/line?

[Edited on February 4, 2006 at 2:13 PM. Reason : .]

2/4/2006 2:13:09 PM

0.069 gal/line

tran said smooth pipe in the lecture
there is an arrow on the moody diagram that points to the smooth pipe line

2/4/2006 2:34:13 PM

my TA said "You are supposed to be using the roughness over diameter of 0.0004"

2/4/2006 2:47:36 PM

^yeah

2/4/2006 2:51:34 PM

ok the line for .0004 relative roughness does not extend far enough to the left for reynolds numbers around 5000. wtf is goin on here?

2/4/2006 3:09:49 PM

The roughness is so small, and so is the diameter, that you get a small epsilon/diameter value. If you follow the line, it runs into the smooth pipe line near the 2-5 x 10^3 Reynolds number values.

2/4/2006 4:25:25 PM

what range are most of yall getting for the Reynolds number?

2/4/2006 4:46:17 PM

10^3 through 10^4 for the reynold's number. conversion is tedious, but you have to do it right if you want your number to come out right.

2/5/2006 11:19:35 PM

my values fall between 5635 - 9284

2/5/2006 11:30:05 PM

how was the apparatus set up? venturi to manometer to volume capture, or manometer to venturi to volume capture?

2/6/2006 10:10:41 AM

just use the apparatus sketch on the lab handout sheet.

2/6/2006 10:11:41 AM