FLOW THROUGH VENTURI TUBE AND ORIFICE PLATE
TITLE:
FLOW THROUGH VENTURI TUBE AND ORIFICE PLATE
OBJECTIVE:
Ø To determine the coefficient of discharge of Venturi tube.
Ø To determine the coefficient of discharge of Orifice plate.
THEORY:
Bernoulli’s Equation:
p1 + v1 + z1 = p2 + v2 + z2
ρg 2g ρg 2g
v2 = A1v1
A2 (continuity equation)
p1 = h1
ρg (pressure head at 1)
p2 = h2
ρg (pressure head at 2)
z1 =z2 (horizontal flow)
Flow through Venturi Tube and Orifice Plate.
v1 = 2g(h1-h2)
(A1)2 – 1
√ (A2)2
Theoretical Discharge
Q theoretical = A1v1 = A1 2g(h1-h2)
(A1)2 – 1
√ (A2)2
Actual Discharge
Q actual = Cd Q theoretical ; where Cd is coefficient of discharge.The actual discharge is obtained by measuring directly the quantity of following water per second.
APPARATUS:
Ø Adjustable measurement system
Ø Back wall
Ø Ball cocks for shutting off part sections.
Ø Double pressure gauge
Ø Drain
Ø Inlet (concealed)
Ø Measurement object-flow measurement
Ø Measurement object-shut-off devices
Ø Tubular steel frame with suction pads
PROCEDURES:
Part A: Flow through Venturi Tube
- Inlet and throat diameters of the Venturi tube were recorded.
- The Venturi tube was fixed into section 6.
- All valves were closed except those that will let the water flows from the tank to section Venturi tube and return back to the tank. The direction of flow in the pipe was verified.
- The manometer hoses were connected to the pressure tapping points of the Venturi tube.
- The pump was switched on. Air bubble was removed from the apparatus.
- The valve was adjusted on the left side of the Venturi tube to a certain position.
- The valve of h1 and h2 were measured and recorded.
- The actual volume flow rate (Q actual).
- Step 6 to 8 for 5 values of Q actual were repeated.
Part B: Flow through Orifice Plate
1. Inlet and throat diameters of the Orifice plate were recorded.
2. The Orifice plate was fixed into section 6.
3. All valves were closed except those that will let the water flows from the tank to section Orifice plate and return back to the tank. The direction of flow in the pipe was verified.
4. The manometer hoses were connected to the pressure tapping points of the Orifice plate.
5. The pump was switched on. Air bubble was removes from the apparatus.
6. The valve was adjusted on the left side of the Orifice plate to a certain position.
7. The valve of h1 and h2 were measured and recorded.
8. The actual volume flow rate (Q actual).
9. Step 6 to 8 for 5 values of Q actual were repeated.
DATA AND CALCULATION:
Part A: Flow through Venturi tube.
| Inlet inside diameter : | d1= 28.4 mm = 0.0284 m |
| Inlet cross-sectional area: | A1= 2.534×10-3 m2 |
| Throat inside diameter: | d2= 14.0mm = 0.014 m |
| Throat cross-sectional: | A2= 0.1539×10-3m2 |
| Area ratio: | A1/A2= 16.465 |
| Gravitational acceleration: | g= 9.81 m/s2 |
| No. | Volume Measured, (liters) | Time, (s) | Q actual | h1, (mm) | h2, (mm) | h1-h2, | Q theoretical, (m3/s) | ||
| (Liters/s) | (m3/s) | (mm) | (m) | ||||||
| 1. | 1 | 5.35 | 0.187 | | 96.0 | 28.57 | 67.25 | 0.06725 | |
| 2. | 1 | 7.38 | 0.136 | | 91.0 | 33.2 | 57.8 | 0.0578 | |
| 3. | 1 | 8.9 | 0.112 | | 86 | 37.3 | 48.7 | 0.0487 | |
| 4. | 1 | 9.5 | 0.105 | | 81 | 41.5 | 39.5 | 0.0395 | |
| 5. | 1 | 10.21 | 0.098 | | 76 | 45.5 | 30.5 | 0.0305 | |
Part B: Flow through Orifice plate.
| Inlet inside diameter : | d1=18.5 mm = 0.0185 m |
| Inlet cross-sectional area: | a1= 0.2688×10-3m2 |
| Throat inside diameter: | d2= 14.0 mm = 0.014 m |
| Throat cross-sectional: | A2= 0.1539×10-3m2 |
| Area ratio: | A1/A2=1.747 |
| Gravitational acceleration: | g= 9.81 m/s2 |
| No. | Volume Measured, (liters) | Time, (s) | Q actual | h1, (mm) | h2, (mm) | h1-h2, | Q theoretical, (m3/s) | ||
| (Liters/s) | (m3/s) | (mm) | (m) | ||||||
| 1. | 1 | 9.53 | 0.105 | | 73.5 | 64 | 9.5 | 0.0095 | |
| 2. | 1 | 8.66 | 0.115 | | 78.5 | 61.1 | 17.4 | 0.0174 | |
| 3. | 1 | 8.10 | 0.123 | | 83.5 | 58 | 25.5 | 0.0255 | |
| 4. | 1 | 7.93 | 0.126 | | 88.5 | 74.5 | 14.0 | 0.014 | |
| 5. | 1 | 3.88 | 0.258 | | 93.5 | 51.1 | 42.4 | 0.0424 | |
DISCUSSION (venturi & orifice)
Through the experiment, the objective had been achieved and as follows:
o To determine the coefficient of discharge of Venturi tube. where from the experiment, the data is______ while from theoretical calculation is______.
o To determine the coefficient of discharge of Orifice plate. where from the experiment, the data is______ while from theoretical calculation is______.
CONCLUSION
- As a conclusion the experiment were successfully carried out, even though the data collected are varies with theoretically equation because the different are minute and can be negligible.
- The different between experiment data theoretically equation are mainly due to human and servicing factors such as:
a. Parallax error – occur during captured the value of water level, h1 and h2.
b. Bubble inside the pipe line was not properly flushed during bleeding.
- The are no relative motion between the fluid particles. The only stress will be normal stress which is equal to the pressure.
RECOMMENDATION
There are a lot of possibilities for an experiment will having an error and as per discuss above. Therefore it is recommendation are as follows:
a. Change to the new equipment and apparatus.
b. Built the platform when taking the parallax error.
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