Reg. No.
B.E. B.Tech. DEGREE EXAMINATION, MAY 2017
Third Semester
Mechanical Engineering
14UME304 FLUID MECHANICS AND MACHINERY
(Regulation 2014)
Duration: Three hours Maximum: 100 Marks
Answer ALL Questions
PART A (10 x 1 10 Marks)
1. Which one of the following sets of conditions clearly apply to an ideal fluid Viscous and compressible Non-viscous and incompressible
Non-viscous and compressible Viscous and incompressible
2. Which one of the following is the correct statement? Streamline, path line and streak line are identical when the Flow is steady Flow is uniform Flow velocities do not change steadily with time Flow is neither steady nor uniform
3. The Bernoulli's equation refers to conservation of
Mass Linear momentum Angular momentum Energy
4. The following instruments are used in the measurement of discharge through a pipe:
1. Orifice meter,
2. Flow nozzle and
3. Venturimeter. Decreasing order of use
2 3 1 1
5. Reynold's number is given by
Viscous force Inertial force Inertial force Viscous force Gravitational force Viscous force Pressure force Viscous force
Question Paper Code: 41734
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6. Models are known as undistorted model if the prototype and model are having different scale ratios the prototype and model are having same scale ratio the prototype and model are kinematically similar none of these 7. Consider the following statements
1. Pelton wheel is a tangential flow impulse turbine 2. Francis turbine is an axial flow reaction turbine
3. Kaplan turbine is a radial flow reaction turbine Which of the above statements is/ are correct 1 and 3 1 alone 2 alone 3 alone
8. The use of a draft tube in a reaction type water turbine helps to Prevent air from entering Increase the flow rate Convert the kinetic energy to pressure energy Eliminate eddies in the downstream
9. Which one of the following pumps is not a positive displacement pump? Reciprocating pump Centrifugal pump Vane pump Lobe pump
10. Cavitation can take place in case of Pelton Wheel Francis Turbine Centrifugal Pump Both and
PART B x 2 =10 Marks)
11. Define specific gravity with respect to density.
12. State the assumptions used in deriving Bernoulli's equation.
13. State Reynold's model law.
14. Classify hydraulic turbine with respect to head available at inlet.
15. Define coefficient of discharge of reciprocating pump.
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PART C x 16 80 Marks)
16. What are the gauge pressure and absolute pressure at a point 3 m below the free surface of a liquid having a density of 1.53 X 103 kg/m3, if the atmospheric pressure is equivalent to 750 mm of mercury? The specific gravity of mercury is 13.6 and density of water is 1000 kg/m3. Or A hollow cylinder of 150 mm OD with its weight equal to the buoyant forces is to be kept floating vertically in a liquid with a surface tension of 0.45 N/m. The contact angle is 60°. Determine the additional force required due to surface tension.
17. State Bernoulli's theorem for steady flow of an incompressible fluid. Derive an expression for Bernoulli's equation and state the assumptions made. Or A horizontal Venturimeter with inlet diameter 200 mm and throat diameter 100 mm is employed to measure the flow of water. The reading of the differential manometer connected to the inlet is 180 mm of mercury. If Cd 0.98, determine the rate of flow.
18. Using Buckingham's theorem, show that the velocity through a circular orifice in a pipe is given by v √(2gH) f H where v is the velocity through orifice of diameter d and H is the head causing the flow and and are the density and dynamic viscosity of the fluid passing through the orifice and g is acceleration due to gravity. Or Water is flowing through a pipe of diameter 30 cm at a velocity of 4 m/s. Find the velocity of oil flowing in another pipe of diameter 10 cm, if the condition of dynamic similarity is satisfied between the two pipes. The Viscosity of water and oil is given as 0.01 poise and 0.025 poise. The specific gravity of oil 0.8.
19. A Pelton turbine running at 720 rpm uses 300 kg of water per second. If the head available is 425 determine the hydraulic efficiency. The bucket deflects the jet by 165°. Also find the diameter of the runner and jet. Assume C 0.97 and f 0.46, Blade velocity coefficient is 0.9. Or
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A Francis turbine developing 16120 kW under a head of 260 m runs at 600 rpm. The runner outside diameter is 1500 mm and the width is 135 mm. The flow rate is 7 m3/s. The exit velocity at the draft tube outlet is 16 m/s. Assuming zero whirl velocity at exit and neglecting blade thickness determine the overall and hydraulic efficiency and rotor blade angle at inlet. Also find the guide vane outlet angle.
20. The following details refer to a centrifugal pump. Outer diameter: 30 cm, Eye diameter: 15 cm, Blade angle at inlet: Blade angle at outlet: 25° and Speed 1450 rpm. The flow velocity remains constant. The whirl at inlet is zero. Determine the work done per kg. If the nanometric efficiency is determine the working head. If width at outlet is 2 cm, determine the power ηo 76%. Or A reciprocating pump with plunger diameter of 120 mm and 200 mm stroke has both delivery and suction pipes of 90 mm diameter. The suction length is 9 m and the delivery length is 18 m. The atmospheric head is 10.3 m of water head. Determine the suction head and the delivery head due to acceleration at speeds 30, 40, 50, 60 rpm operating speeds.