**4HE
Fluid Mechanics - October 1998**

Part A - (20 X 2 = 40 marks)

- Differentiate between Newtonian and Non-Newtonian fluids.
- Write the unit for surface tension coefficient.
- What are the two important characteristics of potential flow?
- Define 'mass velocity' of fluid through a channel.
- What is Mach number? Define the Mach number for an ideal gas.
- Define 'Boundary Layer'.
- Write Ergun's equation for pressure drop through a packed bed.
- Classify positive displacement pumps.
- Write an expression for head loss due to sudden expansion of the fluid.
- Write the physical significance of Froude's number.
- Write few industrial applications of fluidized beds.
- Inclined manometer is used for ____________.
- Define 'Manometric efficiency' in centrifugal pump.
- Write the principle of Pitot tube.
- Why is rotameter called an area meter?
- What is 'What Hammer'?
- What is Priming?
- What is the function of volute in a centrifugal pump?
- Write two differences between compressors and blowers.
- Define 'Form drag' and 'Skin drag'.
- (a) With the help of shear stress-shear rate diagram, explain the classification of non-Newtonian fluids. Discuss their important characteristics. (8)
- (a) Define Similitude. Explain the different types of similarities in fluid flow processes. (4)
- (a) Assuming one dimensional fluid flow, write the continuity, momentum and mechanical energy equations for an incompressible fluid. (6)
- (a) Discuss the various zones for development of turbulent boundary layer on a flat plate. (4)
- (a) Explain the principle, construction and working of an orifice meter with the help of a neat sketch. (6)
- (a) Compare between an orifice meter and venturi meter. (4)
- (a) With the help of a neat sketch, explain the flow of fluid through granular solids. (6)
- (a) Explain the different types of fluidization and state their conditions. State commercial applications of fluidized bed. (6)
- (a) Classify pumps. With the help of a neat sketch, explain the operation of a centrifugal pump. (6)
- (a) Explain the principle of operation for fans, blowers and compressors. (6)

Part B - (5 X 12 = 60 marks)

(b)A simple U-tube manometer is installed across an orifice meter. The manometer is filled with mercury (sp.gr = 13.6) and the liquid above the mercury is carbon tetra chloride (sp.gr = 1.6). The manometer reads 300 mm. What is the pressure difference over the manometer in Newtons per square meter? (4)

(b) Pressure drop of a homogeneous fluid in a straight smooth pipe (DP) is a function of the pipe geometry (diameter d, and length l), the physical properties of the fluid (densityr and viscosity m) as well as its velocity v.

DP = f (d, l, r, m, v)

Using dimensional analysis, find out the relationship between dimensionless groups, defining the above fluid flow process. (8)

(b) Discuss the velocity profiles for laminar and turbulent fluid flow through a pipe. What is the relationship between skin friction and wall shear in a pipe? (6)

(b) Brine is to be pumped through a 25 m of smooth copper tube having an inside diameter of 2.5 cm. Flow rate of brine is 100 litre/min. Calculate the following:

(i)Pressure drop from friction in kN/m^{2}

(ii)Power required to overcome friction.

Specific gravity of brine = 1.15

Viscosity of brine = 2.5 cp

Friction factor f = 0.0015 + 0.125Re

(b) Discuss the principle and applications of Doppler effect in flow measurement. (6)

(b) An oil of specific gravity 0.8 is flowing through a venturi meter having inlet diameter 20 cm and throat diameter 10 cm. The mercury differential manometer shows a reading of 25 cm. Calculate the discharge of oil through the horizontal venturi meter. Take C_{d }= 0.98 (8)

(b) Derive Carman-Kozney equation for pressure drop through a packed bed. (6)

(b) Differentiate between Loading and Flooding. How will you estimate the flooding velocity in a packed tower? (6)

(b) State the principle and applications of air lift and diaphragm pumps. (6)

(b) A centrifugal fan is used to take flue gas at rest and at a pressure of 700 mm Hg and a temperature of 90^{o}C and discharges it at a pressure of 765 mm Hg and a velocity of 45 m/s. Calculate the power required to move 18000 m^{3}/hr of gas. Efficiency of the fan is 65%. Molecular weight of the gas = 32. (6)