Venturimeter Viva Questions and Answers
1. Draw the Venturimeter and mention the parts
Parts of Venturimeter: Convergent section, Throat, Divergent section, Pressure taps (inlet and throat), Inlet pipe, Outlet pipe.
2. Why the divergent cone is longer than convergent cone in Venturimeter?
The divergent cone is longer to reduce pressure losses by preventing flow separation and turbulence during expansion.
3. Compare the merits and demerits of Venturimeter with orifice meter
Venturimeter: High accuracy (Cd ~ 0.98), less pressure loss, expensive, bulky.
Orifice meter: Lower accuracy (Cd ~ 0.6), more pressure loss, cheaper, compact.
4. Why Cd value is high in Venturimeter than orifice meter?
Because Venturimeter has gradual contraction and expansion, minimizing turbulence and energy losses, resulting in a higher coefficient of discharge.
5. Mention few discharge measuring devices
Venturimeter, Orifice meter, Rotameter, Pitot tube, Flow nozzle, Weirs and flumes.
6. What is the use of Venturimeter?
It is used to measure the discharge (flow rate) of fluid in pipelines.
7. What is Venturimeter constant?
A constant that combines the coefficient of discharge and geometric factors, used in the discharge calculation formula.
8. What is the principle of Venturimeter?
Based on Bernoulli’s principle: an increase in fluid velocity causes a pressure drop, which is measured to determine flow rate.
9. Why is the pressure difference between entrance and throat section increased due to friction?
Because friction causes energy loss, increasing the pressure drop needed to maintain the same flow rate.
10. It is recommended that the diffuser angle of a venturimeter should be kept less than _____
7 degrees, to avoid flow separation and reduce energy loss.
11. Define Venturimeter
A device used to measure fluid flow by correlating pressure difference with velocity changes in a constricted pipe.
12. List out the types of Venturimeters
Horizontal Venturimeter, Vertical Venturimeter, Inclined Venturimeter.
13. Define horizontal Venturimeter
A Venturimeter installed horizontally; pressure difference is mainly due to velocity change.
14. Define vertical Venturimeter
A Venturimeter installed vertically; pressure difference influenced by velocity and gravity.
15. Define inclined Venturimeter
A Venturimeter installed at an angle; used when vertical or horizontal installation isn't possible.
16. What is the use of horizontal Venturimeter?
Used when gravity effects are negligible and flow is uniform.
17. What is the use of vertical Venturimeter?
Used to measure flow when gravity influences pressure differences (rising/falling fluids).
18. What is use of inclined Venturimeter?
Used in pipelines where horizontal or vertical installation isn't possible or to study flow at an angle.
19. What is the range of throat ratio?
Typically between 0.25 and 0.5 (ratio of throat diameter to pipe diameter).
20. What is the range of Cd for Venturimeter?
Between 0.96 and 0.99.
21. Venturimeter are suitable for measuring low velocities or high velocities?
Suitable for measuring high velocities.
22. Who found Venturimeter?
Giovanni Battista Venturi.
23. In which year Venturimeter is found?
1797.
24. Write the discharge formula of Venturimeter.
Q = Cd × A1 × √[ (2g h) / (1 - (A2/A1)²) ]
Where Q = discharge, Cd = coefficient of discharge, A1 = inlet area, A2 = throat area, h = pressure head difference, g = acceleration due to gravity.
25. What is meant by calibration?
The process of adjusting an instrument to match a known standard for accuracy.
26. What is meant by convergent section in Venturimeter?
The section where the pipe diameter decreases, causing fluid velocity to increase.
27. What are the materials used in construction of Venturimeter?
Cast iron, bronze, stainless steel, and plastic (for lab models).
28. What are the precautions to be taken in this experiment?
Remove air bubbles, ensure leak-proof setup, maintain steady flow, read manometer carefully, avoid sudden valve changes.
29. Define Venturi effect.
The reduction in fluid pressure when it flows through a constricted section of pipe.
30. For what purpose Venturimeter is used? Write answer for this viva.
Used to measure the flow rate of incompressible fluids in pipelines by measuring pressure difference across a constriction.