Calculations and Analysis
1. what does h1 and h2 mean? They represent the pressure differential throught the pipe
gantry set-up. since the amount of energy in a system must remain constant, energy
therefore can only change from one form to another. In the Bernoulli eqn, a change in pipe
flow cross section area results in a change in both pressure and velocity. For example
chaging from a small diameter to a large diameter will result in a change from high velocity
(hi KE), low pressure liquid to a low velocity(low KE), high pressure liquid. This situation
makes sense for the three small pipes but does not make sense for ther large copper pipe. It
depends really on where the static tubes are located.
h1=P1/γ +z1
2.
3.
4.
5.
6.
h2=P2/γ +z2
this data is found in the excel sheet
this data is found in the excel sheet
this data is found in the excel sheet
a.
The calculations are extremely sensitive to variations in one parameter. What
is this parameter, and how does it affect the results?
The parameter is the pipe diameter D. Since volume flow rate is a function of D and
the given formula is
𝜋𝐷 4 Δ𝑝
𝑄=
( )
128𝜇 𝐿
b.
What is the effect of parallel flow on the pipelines of line A ? Qin = Qout.
Since the individual areas of the two pipes is smaller than the collective area of one
large pipe, there must be an increase in fluid velocity to maintain constant volume
flow rate. Also the entrance length for a small diameter pipe will be shorter in order to
fully develop the flow into a fully viscous flow
c.
a serious problem occurs with the large copper pipe B. I am not too sure why
we cannot obtain e/D data, but I am pretty sure that it has something to do with the
pipe length and its diameter. With a Re number and f number of 1.4x10^4 and .002
respectively, the e/D number if off the chart. I believe it may be the the flow is not yet
fully formed and is still an inviscid flow.
If the entrance length is E= 50-150 x pipe diameter, then E ranges from 1.14m to
3.43m. our pipe length is 0.9m.
d.
Knowing that the horizontal pipelines are 5 year old copper pipes, compare
their equivalent sand roughness with literature values. How do you account for any
discrepancies ?
as pipes age, they gather deposits such as lime, scale and corrosion and these deposits affect
the roughness of the inside wall of the pipe. As the pipe internal wall increases in roughness,
its e/D ratio increases as well. this has an overall affect on the flow of a fluid though a pipe.
Normally a rougher internal wall will result in increased friction between the pipe wall and
the fluid and the velocity of a fluid through this pipe will be retarded.
Copper and stainless pipes can be modelled as pipes constructes by drawn tubing. Brand
new items constructed by this method have a roughness of about 0.00015mm. as the pipes
have aged their e/D ratio has increased and though our experimental data shows that on
average the small copper tubing has an e/D of 0.02mm and the stainless pipe 0.497mm.. this
is a significant difference form the values of a brand new pipe.