Question Paper: Fluid Mechanics : Question Paper Dec 2015 - Mechanical Engineering (Semester 4) | Mumbai University (MU)
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## Fluid Mechanics - Dec 2015

### Mechanical Engineering (Semester 4)

TOTAL MARKS: 80
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any three from the remaining questions.
(3) Assume data if required.
(4) Figures to the right indicate full marks.
1 (a) Define a fluid and distinguish between ideal and real fluids.(5 marks) 1 (b) A stone weights 2KN in air and 168N in water. Calculate the volume and specific gravity.(5 marks) 1 (c) Explain Hydrostatic law.(5 marks) 1 (d) Define steam lines, path lines and streak lines.(5 marks) 1 (e) Define Mach number, stagnation density and stagnation temperature.(5 marks) 2 (a) The velocity components in two dimensional flow fields are as follows
u=y3/3+2x-x2y, v=xy2-2y-x3/3.
i) whether the flow is possible
ii) obtain an expression for steam function
iii) obtain an expression for potential function.
(10 marks)
2 (b) A sliding gate 3m and 1.5m high situated in a vertical plane has a coefficient of friction between itself and guide of 0.18. If the gate weight is 19n and its upper edge is at a depth of 9m, what vertical force is required to raise it? Neglect buoyancy force on gate.(10 marks) 3 (a) Starting from the Navier Stokes equation for an incompressible Newtonian fluid derive Bernoulli's equation starting the assumptions.(10 marks) 3 (b) Derive the expression for stagnation density and stagnation temperature.(10 marks) 4 (a) A pipeline of length 2400m is used for power transmission. If 115KW power is to be transmitted through the pipe in which water having a pressure of 500 N/cm2 at inlet is flowing? Find the diameter of the pipe and efficiency of transmission if the pressure drop over the length of pipe is 100 N/cm2. Take f=0.026 also find diameter if pipe corresponding to maximum efficiency of transmission.(10 marks)

### Write short note on.

4 (b) (i) Moody's diagram(5 marks) 4 (b) (ii) Major and minor losses.(5 marks) 5 (a) A normal shock wave occurs in a duct in which air is flowing at a Mach number of 1.5. The static pressure and temperature upstream of the shock wave is 1.5 bar and 270°C. Determine pressure, temperature and mach number downstream of the shock. Also calculate strength of shock.(10 marks) 5 (b) Explain Prandtl's mixing length theory.(10 marks) 6 (a) The velocity profile within a laminar boundary layer over a flat plate is given by the equation.
u/U =2(y/δ) - (y/δ)2
Where U is the mean stream velocity and δ is the boundary layer thickness. Determine the displacement thickness and momentum thickness.
(10 marks)

### Explain

6 (b) (i) Aerofoil theory(5 marks) 6 (b) (ii) Reynolds Transportation theorem.(5 marks)