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Friday, 14 October 2016

Fluid Mechanics- Model question paper for B.E/B.Tech Mechanical Engineering



1(a) Mention any 4 properties of a fluid. (04 Marks)
(b) With a neat sketch, explain the working of differential U-tube manometer. (06 Marks)
(c) A square lamina of side 0.6 m is immersed in water with one of its diagonal horizontal to the surface of water and the top corner point is 0.6 m below the free surface of water. Calculate the force on one side of the lamina and the location of centre of pressure. (06 Marks)
(d) Two circular discs of diameter of 200 mm are mounted coaxially and the gap of 0.13 mm between the plates is filled a viscous liquid (viscosity 0.14 Pa.s). Calculate the torque necessary to rotate one disc relative to other at a uniform speed of 7 rev/s. (04 Marks)
2(a) What are streamline, pathline and streak line? Write equations. (06 Marks)
(b) A stream function for a two dimensional flow field is expressed by an equation ψ = 3x + 4y + 2x2 – 2y2. Determine the corresponding velocity potential function. (04 Marks)
(c) Explain briefly the principle of superposition and show how it can be used to analyze the flow over arbitrary shaped bodies. (06 Marks)
(d) A 5 cm × 3 cm venturimeter placed at an angle of 300 with the horizontal carries a liquid of specific gravity of 0.80. The deflection of a differential mercury manometer shows deflection of 10 cm for a particular flow rate. Estimate the flow rate. Take coefficient of discharge of the venturimeter as 0.96. (04 Marks)
3(a) Explain Reynolds transport theorem. (06 Marks)
(b) A small hydropower plant operates under 100 m of head and using 30 m3/s of water to produce electric power. Head loss due to friction from inlet to exit is 20 m. Estimate the power extracted by the turbine if it discharges water at 2 m/s into the atmosphere at its exit. (04 Marks)
(c) Explain the properties of stress tensor. ( 06 Marks)
(d) Explain the terms vorticity and circulation. (04 Marks)
4(a) Write continuity equation, equations of motion and energy equation in spherical coordinates. (05 Marks)
(b) Prove that in an annulus pipe, stresses are positive at the walls. (07 Marks)
(c) Derive Hagen-Poiesuille equation for the flow through a circular pipe. (08 Marks)
5(a) Explain Ossen approximation. (06 Marks)
(b) Explain the properties of boundary layer equation. (06 Maerks)
(c) Show that in a two dimensional creeping flow, the stream function obeys the biharmonic equation. (04 Marks)
(d) What is the head loss in meters of water in a 300 m long smooth 10 cm diameter pipe carrying 0.1 m3/s of water at 200C. Use Blausius formula for calculating friction factor. (04 Marks)
6(a) Write a short note on flow over bluff bodies. (04 Marks)
(b) Distinguish between Boussinesq hypothesis and Prandtl’s mixing length hypothesis. (08 Marks)
(c) Define Mach number. What are zone of action and zone of silence? (04 Marks)
(d) Estimate the velocity and Mach number of a projectile which reflects a shock wave of angle 300 in air at pressure of 0.95 kg/cm2 at a temperature of 30C. (04 Marks)
7(a) Explain Buckingham π-theorem. (04 Marks)
(b) As per Stoke’s law, the terminal velocity V of a small sphere of density ρs and diameter D depends on the density of the liquid ρf, dynamic viscosity µ and acceleration due to gravity g. Express the functional relationship between the variables in a dimensionless form. (06 Marks)
(c) What are the assumptions made during the internal estimate of the error? (04 Marks)
(d) A 1:50 scale model of a boat has a wave resistance of 0.02 N when operating in water at 1 m/s. Find the corresponding prototype resistance. Find also the horsepower required for the prototype. What velocity does this test represent in the prototype? (06 Marks)
8(a) Using a neat sketch, explain the working of Laser Doppler Anemometer. (08 Marks)
(b) Reynolds stress model is a seven-equation model and is well suited for fluid flow analysis through complex geometries. Explain. (04 Marks)
(c) What purpose Nacelle and gearbox serves in a wind turbine? (04 Marks)
(d) Mention some disadvantages of hydropower. (04 Marks)

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