B.Tech II Year II Semester Examinations, May - 2019

FLUID MECHANICS

(Common to ME, MECT)

Time: 3 hours Max. Marks: 75

Note: This question paper contains two parts A and B.

Part A is compulsory which carries 25 marks. Answer all questions in Part A.

Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks.

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PART - A (25 Marks)

1. 1. Define kinematic viscosity and state its units. (2 Marks)
   2. Explain the terms stream line, path line and streak line. (3 Marks)
   3. Define momentum thickness. (2 Marks)
   4. Distinguish between laminar and turbulent boundary layers. (3 Marks)
   5. Define the terms hydraulic gradient line and total energy line. (2 Marks)

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   6. State the applications of Bernoulli’s equation. (3 Marks)
   7. Define displacement thickness. (2 Marks)
   8. What is the effect of compressibility on fluid flow? (3 Marks)
   9. Define and explain Mach number. (2 Marks)
   10. Differentiate between pipe flow and open channel flow. (3 Marks)

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PART - B (50 Marks)

(Answer any one full question from each unit. Each question carries 10 marks)

UNIT - I

1. 2. a) Define surface tension. Derive the relation between surface tension and pressure inside a droplet of liquid in excess of outside pressure. (5 Marks)
   b) A U-tube manometer is used to measure the pressure of water in a pipeline, which is in excess of atmospheric pressure. The right limb of the manometer contains mercury and is open to atmosphere. The contact between water and mercury is 12 cm below the surface of water in the pipeline. What is the pressure of water in the pipeline, if the difference of mercury level in the two limbs of manometer is 20 cm? (5 Marks)
2. OR

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3. 3. a) Derive the three dimensional continuity equation in Cartesian co-ordinate system. (5 Marks)
   b) The stream function is given by Ψ = 5x² - 2y³. Determine the magnitude of the velocity components at the point (2, 2). (5 Marks)

UNIT - II

1. 4. Explain the Von Karman momentum integral equation for boundary layer flows. (10 Marks)
2. OR
3. 5. Explain the phenomenon of separation of boundary layer. What are the methods to control boundary layer separation? (10 Marks)

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UNIT - III

1. 6. Derive Euler’s equation of motion along a stream line and hence derive Bernoulli’s equation for steady incompressible fluid flow. State the assumptions made. (10 Marks)
2. OR
3. 7. A horizontal venturimeter with inlet diameter 20 cm and throat diameter 10 cm is used to measure the flow of water. The pressure at inlet is 17.658 N/cm² and the vacuum pressure at throat is 30 cm of mercury. Find the discharge of water through the venturimeter. Take C_d = 0.98. (10 Marks)

UNIT - IV

1. 8. A crude oil of viscosity 0.97 poise and relative density 0.9 is flowing through a horizontal circular pipe of diameter 100 mm and of length 10 m. Calculate the difference of pressure at the two ends of the pipe, if the rate of oil flowing through the pipe is 25 liters/sec. (10 Marks)
2. OR

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3. 9. Derive Darcy-Weisbach equation for friction loss in pipe. (10 Marks)

UNIT - V

1. 10. What do you understand by (i) subsonic flow, (ii) sonic flow, (iii) supersonic flow, and (iv) hypersonic flow? Give examples. (10 Marks)
2. OR
3. 11. Define specific energy. Draw specific energy curve and explain its importance in open channel flow. (10 Marks)

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