The purpose of the first experiment was to find speeds in the pipe utilizing the Pitot tubing to mensurate the dynamic force per unit area of the traveling air in the pipe by comparing this with the inactive force per unit area. The consequence showed that the distance across the country increases as the speed additions.
The 2nd purpose of this experiment was to find the discharge coefficient by experimentation for an opening home base metre of the air flow in the pipe. Besides to find the force per unit area distribution along the pipe downstream of the opening home base by utilizing the inactive force per unit area tapping ‘s provided. The consequence showed that flow rate additions as the damper was bit by bit opened.
There were two parts to this experiment, in the first portion a Pitot tubing was used to research the developing boundary bed in the entry length of a pipe which has air drawn through it. The Pitot tubing was besides used to find the speed distribution profiles at assorted transverse subdivision. The purpose of the 2nd portion of the experiment was to find the discharge coefficient for an opening home base metre fitted in an air flow pipe. Besides, by utilizing the inactive force per unit area tapping ‘s to find the force per unit area distribution along the pipe downstream of the opening home base.
Literature reappraisal
The opening metre: the opening metre consists of a level opening home base with a round hole drilled in it ( Donald, 1971 ) . It has is a force per unit area pat upstream from the opening home base and another at the downstream ( Donald, 1971 ) . There are in generated three methods of puting the lights-outs ( Donald, 1971 ) . The coefficient of the metre depends upon the place of lights-outs ( Donald, 1971 ) .
Discharge coefficient: is the ratio of the mass flow rate at the terminal of the nose to that of an ideal nose, which expands as indistinguishable working fluid from the same initial conditions to the same issue force per unit area ( Donald 1971 ) . The discharge coefficient varies well with alterations in country ratio and the Reynolds figure ( Donald, 1971 ) . A discharge coefficient of 0.60 may be taken as standard, but the value varies perceptibly at low values of the Reynolds figure ( Donald, 1971 ) .
The venture metre: in the venture meter the fluid is accelerated through a meeting cone of an angle of 15o-20o and the force per unit area difference between the upstream side of the cone and the pharynx is measured and this provides a signal for the rate of flow ( www.scienceamerica.com ) . The fluid slows down in a cone with smaller angle ( 5o-7o ) where most of the kinetic energy is converted back to coerce energy ( www.scienceamerica.com ) . Because of the cone and the gradual decrease in the country there is no ”vena contracta ” ( www.scienceamerica.com ) . The flow country is at a lower limit at the pharynx. High force per unit area and energy recovery makes the venture metre suited where merely little force per unit area caputs are available ( www.scienceamerica.com ) ..
The conelike nose:
It is a device designed to command the way of fluid flow as it enter or exits an enclosed chamber or pipe through an opening ( it ‘s designed to particularly increase speed ) ( Donald, 1971 ) . A nose is frequently a pipe or tubing of changing transverse sectional country and it can be used to direct the flow of a fluid ( www.emersonprocess.com ) . Nozzles are often used to command the rate of flow, velocity, mass, way and the force per unit area of the watercourse that emerges from them ( www.emersonprocess.com ) .
The Pitot tubings
It is a slender tubing that has two holes on it, the front hole is placed in airstream and it is used to mensurate the stagnancy force per unit area ( Donald, 1971 ) . The side hole measures the inactive force per unit area by mensurating the different between these force per unit areas, to acquire the dynamic force per unit area, which can be used to cipher airspeed ( Donald, 1971 ) .
Reynolds figure: It is the ratio of inertial forces be givening to force flow frontward to the syrupy forces be givening to decelerate it down, it proportional to viscosity x speed gradient ( Donald, 1971 ) . It is the control nature of flow i.e. the flow form and whether flow is disruptive or laminar ( Donald 1971 ) .
Theory
Bernoulli ‘s equation provinces:
Stagnation force per unit area = inactive force per unit area + dynamic force per unit area
This can be written as:
V = ( 2 gh ) 1/2 or ( 1 )
V = ( 2 a?†p ) 1/2/ ( ? ) 1/2
In which a?†p is the force per unit area difference between the Pitot tubing and the wall force per unit area tapping measured utilizing the manometer force per unit area transducers ( mm H2O ) . ( Poole, 2011 )
Q = Aj Vj = Ao Cc Vj = Ao Cc Cv ( 2gh ) 1/2 ( 2 )
Where: Q is the discharge ( volume/time )
Aj is coal-black cross-section country at minimal contraction ( vena contracta )
Ao is orifice cross-section country ( =?d2/4: d= opening size )
Vj is coal-black speed at minimal contraction ( vena contracta )
Cc is coefficient of contraction of jet
Cv is coefficient of speed of jet
g is gravitation acceleration ( 9.81 ms-2 )
H is pressure difference ‘head ‘ across opening
These two coefficients are usually combined to give a individual coefficient of discharge:
Cadmium = Cc.Cv
Equation ( 1 ) now becomes Cadmium Ao ( 2gh ) 1/2 ( 3 )
If Q can be determined independently ( Q ) so the discharge coefficient can be determined as follows:
Cadmium = Q/ Ao ( 2gh ) 1/2 ( 4 )
Valuess of Qi can be determined if the standard nose is fitted at the pipe recess if hi = the bead in force per unit area caput across the recess, the discharge:
Qi = AiCD ( 2gh ) 1/2 ( 5 )
In which Ai = nozzle cross-section country ( = ?d2/4 ) and Cadmium assumed to be 0.97
Valuess of H are obtained from the computing machine manometer transducers connected to the pipe recess force per unit area tapping and unfastened to the ambiance ( Poole, 2011 ) .
Re = ?vd/ µ
Where: µ is the coefficient of dynamic viscousness of the air
? is the denseness
V is the average pipe speed ( Qi/Ai )
vitamin D is the pipe diameter
Methodology
There were two parts to this experiment, in the first experiment the Pitot tubing assemble was mounted at place 1 the point nearest to the pipe recess. The speed transverse of the pipe with pitot tubing was carried out. The Pitot tubing was placed at the lowest place in the type and the force per unit area information was recorded utilizing a computing machine package and a stop ticker was started at the same time. The Pitot tubing was left in the place for 25 seconds and so it was moved by 5mm within 10 seconds clip which is 25 to 35 seconds on the halt ticker. The Pitot was so left in this new place for 20 seconds and so the tubing was moved for the 2nd clip window of 10seconds that is 55 seconds to 65 seconds and this was repeated until the terminal of the Pitot tubing was reached. The information was saved on excel. The speed transverse was repeated for the same air flow value at each of other transverse subdivisions at places 3 and 5. The diagram below showed how the equipment was set-up.
Flow control opening home base removed trial pipe anti whirl vanes
Reservoir
Manometer board
Auxiliary adjustments
Figure 1: Equipment set-up for experiment one
In the 2nd experiment an opening home base was inserted in the place in such a manner that the opening with the smallest diameter is confronting the air flow. All the inactive force per unit area tapping point was connected to the manometer tubings but one manometer which is to enter room air force per unit area and it was attached to the first tapping point adjacent to the standard recess nose which was fitted. the bend was turned on with low air flow with the damper home base about closed at 25 at first and all the readings for the manometer tubing was taking, any unfastened air was included every bit good. The procedure was repeated for when the air flow was increased to 50 and 75 severally. The set up for this experiment was similar to the first experiment expect that the opening was inserted at the appropriate point.
Some safety steps were taken during the experiment ; the research lab coat and the oculus protection were worn throughout the experiment.
Consequences
The first experiment
Table 1: Calculated informations at place 1
H16 ( m )
H3 ( m )
H16-H3
Velocity ( m3/s )
Height ( m )
-0.0141
-0.0343
0.0202
0.6295
0
-0.0074
-0.0323
0.0249
0.6989
0.005
-0.0047
-0.0317
0.027
0.7278
0.01
-0.0058
-0.0328
0.027
0.7278
0.015
-0.0034
-0.0311
0.0277
0.7372
0.02
-0.0042
-0.0336
0.0294
0.7594
0.025
-0.0046
-0.0318
0.0272
0.7305
0.03
-0.0041
-0.0326
0.0285
0.7477
0.035
-0.006
-0.0337
0.0277
0.7372
0.04
-0.0049
-0.0332
0.0283
0.7451
0.045
-0.0059
-0.0334
0.0275
0.7345
0.05
-0.0071
-0.0325
0.0254
0.7059
0.055
-0.0076
-0.0343
0.0267
0.7237
0.06
-0.008
-0.0315
0.0235
0.6790
0.065
-0.0101
-0.0334
0.0233
0.6761
0.07
-0.0119
-0.0328
0.0209
0.6403
0.075
-0.0132
-0.0329
0.0197
0.6217
0.078
Table 2: Calculated informations at place 3
H16 ( m )
H5 ( m )
H16-H5
Velocity ( m3/s )
Height ( m )
-0.0141
-0.0343
0.0202
0.6295
0
-0.0074
-0.0323
0.0249
0.6989
0.005
-0.0047
-0.0317
0.027
0.7278
0.01
-0.0058
-0.0328
0.027
0.7278
0.015
-0.0034
-0.0311
0.0277
0.7372
0.02
-0.0042
-0.0336
0.0294
0.7594
0.025
-0.0046
-0.0318
0.0272
0.7305
0.03
-0.0041
-0.0326
0.0285
0.7477
0.035
-0.006
-0.0337
0.0277
0.7372
0.04
-0.0049
-0.0332
0.0283
0.7451
0.045
-0.0059
-0.0334
0.0275
0.7345
0.05
-0.0071
-0.0325
0.0254
0.7059
0.055
-0.0076
-0.0343
0.0267
0.7237
0.06
-0.008
-0.0315
0.0235
0.6790
0.065
-0.0101
-0.0334
0.0233
0.6761
0.07
-0.0119
-0.0328
0.0209
0.6403
0.075
-0.0132
-0.0329
0.0197
0.6217
0.078
Table 3: Calculated informations at place 5
H16 ( m )
H12 ( m )
H16-H12
Velocity ( m3/s )
Height ( m )
-0.0249
-0.0384
0.0135
0.5146
0
-0.0167
-0.0395
0.0228
0.6688
0.005
-0.0124
-0.0394
0.027
0.7278
0.01
-0.0095
-0.0379
0.0284
0.7464
0.015
-0.0068
-0.0402
0.0334
0.8095
0.02
-0.0055
-0.0416
0.0361
0.8415
0.025
-0.0072
-0.0389
0.0317
0.7886
0.03
-0.0082
-0.0387
0.0305
0.7735
0.035
-0.0085
-0.0453
0.0368
0.8497
0.04
-0.0126
-0.0396
0.027
0.7278
0.045
-0.0112
-0.0452
0.034
0.8167
0.05
-0.014
-0.0403
0.0263
0.7183
0.055
-0.0151
-0.0393
0.0242
0.6890
0.06
-0.0174
-0.0399
0.0225
0.6644
0.065
-0.0214
-0.0431
0.0217
0.6524
0.07
-0.0254
-0.0408
0.0154
0.5496
0.075
-0.0263
-0.0401
0.0138
0.5203
0.078
Figure 2: A graph demoing Position Vs. Velocity ( m/s )
Figure 3: A graph demoing Position vs. Velocity ( m/s )
Figure 4: A graph demoing Position vs. Velocity ( m/s )
The 2nd experiment
Table 4: Calculate informations experiment 2
Number
Head
Pressure bead ( millimeter )
Pressure bead ( m )
Velocity ( m/s )
Diameter ( m )
Area ( M2 )
Cadmium
Rhenium
1
h2-h3
1.2
0.0012
0.1534
0.08
0.0050
0.97
879.30
2
h3-h4
5.4
0.0054
0.3255
0.0762
0.0045
0.504
1776.61
3
h4-h5
4.9
0.0049
0.3101
0.0762
0.0045
0.529
1692.42
4
h5-h6
0.8
0.0008
0.1253
0.0762
0.0045
1.309
683.83
5
h6-h7
66.6
0.0666
1.1431
0.05
0.0019625
0.333
4093.99
6
h7-h8
14.7
0.0147
0.5370
0.0762
0.0045
0.305
2931.25
7
h8-h9
10.4
0.0104
0.4517
0.0762
0.0045
0.363
2465.54
8
h9-h10
1.1
0.0011
0.1469
0.0762
0.0045
1.116
801.85
9
h10-h11
1.3
0.0013
0.1597
0.0762
0.0045
1.027
871.69
10
h11-h12
1.8
0.0018
0.1879
0.0762
0.0045
0.872964
1025.73
Figure 5: A graph demoing Quarter flow rate ( m3/s ) Vs. Position
Figure 6: A graph demoing 50 % discharge ( m3/s ) Vs. Position
Figure 7: A graph demoing 75 % Discharge ( m3/s ) Vs. Position
Figure 8: A graph demoing 100 % Discharge ( m3/s ) Vs. Position
Figure 9: A graph demoing Cd vs. Reynolds figure
Figure 10: A graph demoing Reynolds figure Vs. Position
Discussion of the consequences
The first experiment
It can be seen from figure 2 that the speed seems to be changeless while the place additions and this means that the speed profile is near to the entryway of the pipe. Figure 3 shows that the speed increases in a spot by spot while the place additions faster which implies that a boundary bed is formed at the wall of the pipe. From figure 4 shows that the speed increases easy while the place increases faster this means that the flow is to the full developed and the boundary bed takes up the whole pipe. It can besides that the speed of the pipe at place 5 is greater than the speeds at the Centre of the than that of the place 1 and 3. This is so because there are shear emphasis between wall pipe and the fluid. Further down the pipe the speed of the fluid slows down near the borders of the pipe and accelerate in the Centre and the ( q=av ) where Q and a are changeless.
The 2nd experiment
The force per unit area difference between the atmospheric force per unit area and that of the fluid drops when the Pitot tubing was removed. However, the force per unit area difference at zero distance is changeless throughout the opening this is because the speed of the fluid is changeless. From the Bernoulli ‘s theorem of continuity provinces ”for an inviscid flow an addition in the velocity of fluids occurs at the same time with lessening in force per unit area ” .
The force per unit area difference between the caputs, the discharge flow rate additions with distance from the opening as shown in table 4 and from figure 5-8 as good. It can be seen that flow rate values was increasing as the damper home base which was used to command the flow rate was bit by bit opened as it can be seen organize the tabular array 4. This was caused by a lessening in the fluid force per unit area throughout the pipe while the flow rate of the fluid where the country is changeless is increasing harmonizing to Bernoulli equation. As the country of the pipe is changeless, an addition in the flow rate causes a bead in the unstable force per unit area along the pipe. So hence, there would be an addition along the pipe of the differential force per unit area.
From table 4 the values of the discharge coefficient calculated from the information is much lesser than that of the value ( 0.97 ) given in the theory subdivision this could be as a consequence of mistakes from the force per unit area at the issue every bit good as nose at the terminal. From figure 9 it can be observed that the graph shows a non-linear line but a curve, at first the Reynolds figure additions with the discharge coefficient but so as the discharge coefficient increases the Reynolds figure lessenings. Figure 10 shows that the graph of Reynolds figure and the place additions and the so decreases and reached a extremum at Re 4200 and place 5 and so it decreases once more.
Decision
It can be concluded that the distance from the across the country increases as the speed increases harmonizing to Bernoulli equation and that flow rate values increases as the damper home base which was used to command the flow rate was bit by bit opened.
Terminology
Ao = opening cross sectional country M2
g = gravitative acceleration ms-2
H = force per unit area difference ‘head ‘ across opening
Q = discharge volume m3/s
Cd = discharge coefficient
Re = Reynolds figure
Ai = recess nose cross sectional country M2
D = diameter m
V = speed
µ = coefficient of dynamic viscousness of the air
? is the denseness