4HE Fluid Mechanics - April 1998
Part A (20 x 2 = 40 Marks)
1. Differentiate between compressible and incompressible fluids.
2. What is kinematic viscosity? Write its unit.
3. Write the physical significance of Reynolds number.
4. What is the relationship between the drag coefficient and Reynolds number in the Stoke's law range (Reynolds number < 1)?
5. Write the principle of orifice meter.
6. What is the head loss of the fluid at the entrance of a straight pipe?
7. Explain 'Cavitation' in pumps.
8. Define 'Minimum fluidization velocity'.
9. Define 'Equivalent diameter' for fluid flow through channels of non-circular cross section.
10. Write the principle of Magnetic flow meter.
11. Write continuity equation for three dimensional motion of an incompressible fluid.
12. Give two industrial applications of packed beds.
13. Write Bernoulli's equation. State its assumptions.
14. Differentiate between reciprocating and centrifugal pumps.
15. Explain the principle of hot wire anemometer.
16. Define 'Volumetric efficiency' of the positive displacement pump.
17. Define NPSH in centrifugal pumps.
18. What are the two types of fluidization?
19. Write the Hagen Poiseuille's equation for laminar flow in Newtonian fluid.
20. Pressure drop is __________ in globe valve as compared to gate valve.
21. Part B (5 x 12 = 60 Marks)

22. (a) Classify fluids. With the help of a neat sketch, explain the principle and applications of an inclined manometer. (6)

(b) Define hydrostatic equilibrium. Express mathematically the condition of hydrostatic equilibrium. (6)

23. Or

24. (a) An open tank holds certain amount of liquid whose relative density is 1.25. The tank is fitted with a manometer to a certain point of its wall and it shows a pressure of Pgage = 0.35 atm, what is the height of liquid level in the tank from the point of connection of the manometer. (4)
25. (b) What are the advantages of dimensional analysis? State Buckingham p theorem. (4)

(c) What are the time-dependent fluids? Classify them with examples. (4)

26. (a) Define Fanning's friction factor. How is it related to the pressure drop? (6)
27. (b) Prove for laminar flow of Newtonian fluids through a pipe, u/umax = 1 - (r/rw)2 (6)

Or

28. (a) Write the continuity and momentum equations for one-dimensional fluid flow. (4)
29. (b) Discuss the boundary layer formation during laminar and turbulent fluid flow. (4)

(c) How will you calculate the Reynolds number and friction factor for a pseudo plastic fluid? (4)

30. (a) Explain the principle, construction and working of a venturi meter with the help of a neat sketch. (6)
31. (b) A horizontal venturi meter having a throat diameter of 20 mm is set in a 75 mm I.D. pipeline. Water at 15oC is flowing through the line. A manometer containing mercury under water measures the pressure differential over the instrument. When the manometer reading is 500 mm, calculate the flow rate. Take Cd = 0.98. (6)

Or

32. (a) With the help of a neat sketch, explain the working principle and operation of a rotameter. (6)
33. (b) Explain the velocity measurement by Pitot tube with the help of a neat sketch. (6)

34. (a) Derive Ergun's equation for determining the pressure drop through a packed bed. (6)
35. (b) Write the important applications of fluidization technique in industries. (6)

Or

36. (a) Explain the terms 'Loading' and 'Flooding' in packed towers. (4)
37. (b) A packed bed of catalyst consisting of spherical particles of 150 mm diameter is subjected to fluidization by using oil of density 900 kg/m3. If the density of particles be 2500 kg/m3, determine the mass flow rate of oil per unit area of bed to initiate fluidization. Porosity of bed = 0.48, dynamic viscosity of oil is 0.003 Pa.s. Assume flow condition to be laminar. (8)

38. (a) Classify positive displacement pumps. Explain the function of each one of them with a neat sketch. (6)
39. (b) An air-lift pump raises water from a well of 120 m deep through a pipe of ID = 100 mm at the rate of 90 m3/hr. Determine the efficiency of pump.

Water level is 45 m below the surface. Air consumption = 400 m3/hr of free air compressed to 900 kN/m2; ratio of specific heats of air (g ) = 1.4. (6)

Or

40. (a) Compare between centrifugal and reciprocating pumps. (6)

(b) Write briefly the characteristic features and applications of fans, blowers and compressors. (6)