Venturi Flow
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Transcript of Venturi Flow
8/8/2019 Venturi Flow
http://slidepdf.com/reader/full/venturi-flow 1/5
8/8/2019 Venturi Flow
http://slidepdf.com/reader/full/venturi-flow 2/5
Reynolds numbers for each section (w/ diameter of the section)
6mm
2
23mm
3
18.4mm
4
16mm
5
16.8mm
6
18.47mm
7
20.16mm
8
21.84mm
9
23.53mm
10
25.24mm
11
26mm
.11e+4 2.02e+4 1.67e+4 1.58e+4 1.51e+4 1.13e+4 1.15e+3 1.02e+4 8.08e+3 7.98e+3 6.47e
The mass flow rates are calculated from the equation where
. Usingour pervious information we can calculate the mass flow rates at each section like we did with
the Reynolds numbers.
Mass flow rates for each section (w/ areas of each section)
1 2 3 4 5 6 7 8 9 10 11
530.9 mm2
422.7
mm2
265.9
mm2
201.1
mm2
221.7
mm2
267.9
mm2
319.2
mm2
374.6
mm2
434.8
mm2
500.3
mm2
530.9
mm2
7.46 kg/s 5.94 3.78 2.86 3.14 3.79 4.50 5.28 6.12 7.05 7.47
e-area
.2042 .1822 .1445 .1257 .1319 .1451 .1583 .1715 .1848 .1982 .2042
e-mass
flow(kg/s)
0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002 0.002
Task 3:
The actual mass flow rates can be determined from our data. Using the amount of weight we
used to displace and the time recorded we can calculate the mass flow rate. However, there
was a lever involved so the weights used are not directly being displaced, rather a percentage
of it. The lever ratio is 3/1, so the weight is 1/3 the actual weight being displaced. All the casesuse 2000grams (6000grams of water displaced). Using the time it took from our stop watch we
can calculate the mass flow rate by taking the mass of the water displaced (weight*3)/time.
2000g 2000g 2000g 2000g 2000g 2000g 2000g 2000g 2000g 2000g 2000g
13.87s 14.5s 17.53s 18.6s 19.46s 26.03s 25.44s 28.63s 36.28s 45.31s 55.94s
.4325 .4138 .3423 .3226 .3083 .2305 .2358 .2096 .1654 .1324 .1073
This data was retrieved from us slowly turning the inlet throttle down, the first data point on
the right is our first reading.
Using the errors from the stop watch of etime = 0.5 seconds, lever ratio~0.0527 of and e mass
of 1 gram (0.001 kg) the e-massflow would be .001*.0527/.5 or e-massflow=0.0001054 kg/s
Task 4:
8/8/2019 Venturi Flow
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In task four we are asked to calculate the coefficient curves versus axial position of the
manometer channels. In figure 2 below we can see this plot. The cases look very similar to each
other were as we turn the inlet throttle down the mass flow rates decrease along with the
discharge coefficient. To calculate the errors from the discharge coefficient we are to use the
formula mass flow ratios of actual/Ideal. Using data from pervious tasks we find that emass-
actual = 0.0001054 kg/s and the emass ideal = 0.002 so the eCD=0.0001054/0.002 eCD=0.0527.In this case all manometers have the same error.
Task 5:
In figure 3 there is a plot of Reynolds number vs CD. However, there must have been an error
with the data because the curve is sporadic and has little trend to it. When compared to a
known venture plot cited in a Fluid mechanics text there is almost no resemblance. I found a
similar plot on me.utexas.edu that I could use as a physical comparison on my report and is
represented in figure 4.
Figures:
Figure 1:
This figure shows the relation of each section of the manometers to the venturi. The venture
graph shows the distance between two succeeding manometers in both x and y direction.
Figure 2:
8/8/2019 Venturi Flow
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in this plot we have graphed distance through the venture (same x axis as figure 1) by the
discharge coefficient (CD) Each case gets its own color and stars where the manometer reads
occurred. The cases seem to have very similar trends with one another, however, with
lowering the mass flow rate the discharge coefficient seems to drop universally.
Figure 3:
In this figure we plot Reynolds number for each case by the discharge coefficient. The data is a
bit sporadic however; I believe the data is supposed to be of parabolic shape do to the venturis
nature
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