Reg. No. :

B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2010

Third Semester

Chemical Engineering

CH 2203 — FLUID MECHANICS

(Regulation 2008)

Time : Three hours Maximum : 100 Marks

Answer ALL questions

PART A — (10 × 2 = 20 Marks)

1. Define non-Newtonian fluids. Give one example.

2. An oil-storage tank has a flat, horizontal, circular roof 36 m in diameter.

Calculate the force exerted by the atmosphere on the roof.

3. A ship having a wetted perimeter of 50 m and length of 140 m is to travel at

5 m/s. If the density of sea water is 1025 kg/m3, calculate the drag force. Take

the drag co-efficient as 0.002.

4. Draw the velocity-radius plot in steady, laminar flow of a Newtonian fluid in a

circular pipe.

5. Which concept is essential while designing full-size equipment from tests on

small-scale physical models?

6. Distinguish between notches and weirs.

7. List the minor losses encountered in pipe systems.

8. Name the velocity ranges for which a fluidized bed can exist.

9. Why are diaphragm pumps widely used as ‘metering pumps’?

10. How are the steam-jet ejectors, found more useful in industrial applications?

PART B — (5 × 16 = 80 Marks)

11. (a) Find the specific gravity, dynamic viscosity and kinematic viscosity of an

oil having density 981 kg/m3. The shear stress at a point in oil is

0.25 N/m2 and velocity gradient at that point is 0.2 per second. Also

determine the compressibility of the liquid, if the pressure is increased

from 0.7 MPa to 1.3 MPa while the volume decreases by 0.15 percent.

Or

(b) A helium balloon is at the same pressure and temperature as the

surrounding air of 1 atmosphere and 20°C. The diameter of the balloon is

3 m. How much payload can the balloon lift, if the weight of the plastic

skin of the balloon is negligible?

Question Paper Code : 53084

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53084 2

12. (a) A metallic ball of 0.002 m drops in a fluid of specific gravity 0.9 and

viscosity 1.5 Ns/m2. If the weight density of the ball is 120 kN/m3, find

the drag force exerted by fluid on metallic ball, the form drag, the skin

drag and the terminal velocity of ball in fluid.

Or

(b) Obtain an expression for velocity distribution in turbulent flow for

(i) Smooth pipes and (8)

(ii) Rough Pipes. (8)

13. (a) State Buckingham’s Pi-theorem and also explain various types of

similarities.

Or

(b) Explain the principle of venturimeter with a neat sketch and discuss the

relative merits and demerits of venturimeter with respect to orifice

meter.

14. (a) A pumping plant forces water through a 600 mm diameter main, the

friction head being 27 m. In order to reduce the power consumption, it is

proposed to lay another main of appropriate diameter along the side of

the existing one, so that two pipes may work in parallel for the entire

length and reduce the friction head to 9.6 m only. Find the diameter of

the new main if, with the exception of diameter, it is similar to the

existing one in every respect.

Or

(b) Explain the fluid flow (concepts) though packed beds and fluidized beds.

15. (a) Explain with neat sketches, the working of air lift pump and single

acting reciprocating pump.

Or

(b) A centrifugal fan is used to take flue gas at rest and at a pressure of 737

mm of mercury and a temperature of 93.3°C and discharge it at a

pressure of 765 mm of mercury and a velocity of 46 m/s. Calculate the

power required to move 16990 m3/hour of gas. The efficiency and

molecular weight of the gas are 65 percent and 31.3 respectively.

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