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

http://slidepdf.com/reader/full/venturi-flow 3/5

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

http://slidepdf.com/reader/full/venturi-flow 4/5

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

8/8/2019 Venturi Flow

http://slidepdf.com/reader/full/venturi-flow 5/5