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2/6/2006 11:38:31 AM

i have a question about Word.

if you copy an equation from the lab .pdf file into your word document, how do you change symbols in the equation to your numbers.

like this:

2/6/2006 12:24:39 PM

is the equation gettin copied in as a picture or actual text? i've never done it so i'm unsure of what u might be doin.

2/6/2006 12:40:49 PM

as a picture

2/6/2006 12:50:15 PM

if it's gettin copied in as a picture there is no way to actually edit the text in the picture within word. did u try selecting the text within the pdf file instead?

2/6/2006 12:52:28 PM

yeah but when i try to copy it into word it's just a jumbled mess

2/6/2006 1:03:36 PM

if you use an equation editor you can just highlight all you text in it and then copy it over to your word document, and its fine

if you dont have an equation editor you can either go onto campus and use the one they have or you can drop me a pm and ill send you one

2/6/2006 1:11:40 PM

What kind of values are ya'll getting for head loss (delta p)?

2/6/2006 1:40:44 PM

I'm talking about the theoretical head loss. And should this number be in feet or inches?

2/6/2006 2:00:14 PM

okay this worked last time, can anybody spot what I'm doing wrong for Reynold's number?

this gives me an Re of 617

2/6/2006 2:38:28 PM

damn those are some insane calculations.

i put everythin in terms of feet, much much easier for findin the Re numbers.

[Edited on February 6, 2006 at 2:41 PM. Reason : i think ur makin it way harder than what it is]

2/6/2006 2:41:02 PM

okay I changed it to ft, and I guess I fixed something because Re came out to be 7416 that time

2/6/2006 2:45:21 PM

What kind of values are ya'll getting for head loss (delta p)? And should it be in in or ft?

2/6/2006 2:51:18 PM

i put my head loss in feet because i left my Q as ft^3/s. that way to maintain ft for the graph.

my lab section's data was wrong since we measured wrong (found out today b4 class) but what i do have:

?Pexp (ft. water)
0.5667
0.9067
1.1333
1.3600
0.2267

?Pthe (ft. water)
0.5842
0.7158
0.9350
1.2408
0.3983

2/6/2006 2:53:34 PM

my TA asked for both p's to be measured with inH2O

I'm getting for my experimental

Dp exp (in H20)
2.72
6.8
14.96
14.96
20.4
28.56

still working on getting pthe to make sense, so far I'm getting like .004

2/6/2006 3:03:45 PM

how did you guys calculate the Delta p exp. im getting a high number compared to delta pthe.

2/6/2006 6:38:29 PM

delta P experimental is what you set it at in the lab

on the manometer

2/6/2006 7:03:54 PM

the head loss equation that is provided in the write-up says that:
delta(p) = f*L/D*((umean)^2)/(2*g)
but the units do not equal a pressure. let's say your umean is in ft/s, and your g is 32ft/s^2, you will have units of delta(p) in "ft".

White's Fluid Mechanics, 5th ed. (p.352) says that:
(hf) = f*L/D*((umean)^2)/(2*g)
and that
delta(p) = rho*g*(hf)
which becomes a unit of pressure

2/7/2006 9:53:38 PM

If this is pressure loss in a pipe this might help some


http://www4.ncsu.edu/~doster/NE402/Laboratories/LossesLab/SinglePhaseLosses.pdf

[Edited on February 7, 2006 at 10:06 PM. Reason : fixed link]

2/7/2006 10:06:05 PM

Quote :

"the head loss equation that is provided in the write-up says that: delta(p) = f*L/D*((umean)^2)/(2*g) but the units do not equal a pressure. let's say your umean is in ft/s, and your g is 32ft/s^2, you will have units of delta(p) in "ft". White's Fluid Mechanics, 5th ed. (p.352) says that: (hf) = f*L/D*((umean)^2)/(2*g) and that delta(p) = rho*g*(hf) which becomes a unit of pressure"

yea i had noticed this after calculating it all through but for the lab writeup it doesnt really matter. my TA said that the head loss was acceptable as a pressure denotation because to get pressure, it'd just be taken a step further with information already obtained and displayed in ur data.

2/7/2006 10:29:31 PM

anyone use MATLAB to find what the integral equals in step 4? i need help doing it in MATLAB as i have no clue what to do.

2/16/2006 3:04:13 PM

anyone...anyone?

2/17/2006 11:35:20 AM

I haven't done it yet but I was planning to use my TI

2/17/2006 11:53:16 AM

how do u do it with a TI? what model u have?

2/17/2006 12:00:59 PM

i think it will be:

"polyfit" command to find an appropriate curve:
http://www.mathworks.com/access/helpdesk/help/techdoc/ref/polyfit.html

"quad" command to find definite integral:
http://www.mathworks.com/access/helpdesk/help/techdoc/ref/quad.html

2/17/2006 12:45:07 PM

ohhh, to find the eqn of the curve you use excel

and choose 4th order polynomial, display eqn

then put the eqn in your calculator and use the integral function to find your points

2/17/2006 12:53:59 PM

I'm having trouble finding the mass flow rate also. The V*r vs. r graph should have r in feet right? I used excel to find a 6th degree polynomial because the other degrees didn't fit our data well. When I integrate this function, I am getting a large mass flow rate. Anyone else having this problem?

2/18/2006 4:14:58 PM

Vr and r should be in terms of feet...everything should always be in terms of feet, never inches. in excel i found a 4th degree polynomial and it fit perfectly. i took the equation and put it into MATLAB and after some tinkering i got the answer to the integral from 0 to 1.89. it turned out to be .9729 which according to my TA is approximately what it should be around; at least for my section.

on a side note, i took the integral and plugged it into my TI-89 and got the same answer as MATLAB so i know mine is right.

[Edited on February 18, 2006 at 4:24 PM. Reason : .]

2/18/2006 4:24:02 PM

what tool/command do you use in excel to get the 4th order eqn

2/19/2006 12:14:39 AM

You right click on a point in your graph and select "add trendline"

2/19/2006 8:38:35 AM

what unit do we use for Pressure of room? Im wondering what to use for the density calculation.

2/19/2006 2:07:37 PM

pressure of room was given in inches Hg. u have to convert it to lbf/ft^2 to be able to use it in density calculation.

2/19/2006 2:24:48 PM

Hey brianj, I got close to your value for the integral. Mine came out to be 0.9991. Here is my question. This may seem stupid, but we need to compute the integral for each radius so we can calculate the mass flow rate at each radius right? Or are we supposed to use the same mass flow rate for all of them? I am confused on this part.

2/19/2006 4:26:06 PM

For Vmean, do we just find one value using the largest radius we recorded data with?

2/19/2006 5:54:23 PM

^^ the integral calculated is already accounting for the change in radius. that's the whole point of taking the integral from 0 to ~2 in ur limits of integration. so u use the integral result, in ur case .9991 and multiply that by 2*Pi*rho. that will be ur total mass flow rate (should be in terms of lbm/s).

^ for Vmean, i used the 1st radius with real data associated with it. because 2.00 inches has 0's for everythin, i used whatever my section's 1st radius was.

2/19/2006 8:32:30 PM

k, another question. What did yall conver the dynamic pressure to?

2/19/2006 10:11:12 PM

Quote :

"pressure of room was given in inches Hg. u have to convert it to lbf/ft^2 to be able to use it in density calculation."

2/19/2006 10:41:57 PM

what did you guys get for density of air? I got 0.00226 slug/ft3

2/19/2006 11:49:59 PM

slug?

shouldnt it be in lbm/ft^3



[Edited on February 20, 2006 at 12:17 AM. Reason : .]

2/20/2006 12:17:00 AM

u have to use both slug/ft^3 and lbm/ft^3 within the lab report due to units needing to cancel out properly. certain parts u'll use the slug term, other part u'll use the lbm term

[Edited on February 20, 2006 at 12:59 AM. Reason : .]

2/20/2006 12:58:10 AM

so what range are you guys getting for V and Vr

my V goes from 60-80 ft/s, and Vr 1-10 ft2/s

2/20/2006 1:12:13 AM

70-90, 1-10

2/20/2006 1:18:00 AM

when I do the integral from 0-2 of Vr, I get something like 12

but my TA said it should be around 1. Any comments?

2/20/2006 1:19:55 AM

whats everyone getting for their mass flow rate. I think we're supposed to get 1ish, im getting just over 2.

2/20/2006 1:20:12 AM

I'm trying to plot pressure (y-axis), distance (x-axis), and velocity (secondary y-axis) on the same chart with Excel. However velocity is stuck to the y-axis, distance is on the secondary y-axis, and pressure is on the x-axis. Anyone know how to force Excel to use certain things for the axis'?

I'm about a data-point away from from throwing my laptop against a wall.

2/20/2006 2:08:06 AM

Nerdchick, my V's go from 58.75 to 85.12 (peaks there) then decreases a bit to 82.73. my Vr values go from 9.25 up to 10.08 then decreasing all the way down to .765. make sure ur units are sound (everything in feet, feet^2/s, ft/s, etc..)

total mass flow rate i got to be .453578 lbm/s. my TA said my integral answer was right and so multiplyin by 2*Pi*rho, i got what i said. rho for me turned out to be .0742 lbm/ft^3 with a pressure of 2109.58 lbf/ft^2 and a temperature of 532.8 degrees Rankine.

2/20/2006 8:12:24 AM

What is the deal with the graphs? Our TA was very ambiguous about what graphs we needed. I know we need the Vr vs. r graph, but what about the pressure vs. r or V vs. r graphs?

2/20/2006 10:26:26 AM

graphs vary from TA to TA. mine only requires the Vr vs. r graph.

2/20/2006 10:54:17 AM

DPK, you can probably fix that by going into "Series" when you're making the chart. Change the data cells for the x and y axis to be what you want.

the easiest thing to do would probably be to just make 2 different charts, unless your TA asked for one.

2/20/2006 11:16:20 AM

Thanks! I'll try that when I get back to the apt later.

Our TA is giving us extra credit if we can plot them all on one chart.

2/20/2006 2:06:26 PM