Question Paper: Fluid Mechanics : Question Paper Jun 2015 - Mechanical Engineering (Semester 3) | Pune University (PU)
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## Fluid Mechanics - Jun 2015

### Mechanical Engineering (Semester 3)

TOTAL MARKS: 100
TOTAL TIME: 3 HOURS
(1) Question 1 is compulsory.
(2) Attempt any four from the remaining questions.
(3) Assume data wherever required.
(4) Figures to the right indicate full marks.

### Answer any one question from Q1 and Q2

1 (a) State and prove Hydrostatic Law.(6 marks) 1 (b) Discuss various types of flows.(6 marks) 2 (a) A body with gravity force of 500 N with a flat surface area of 0.2 m2 slides down a lubricated inclined plane making a 30° angle with the horizontal. For viscosity of 0.1 kg.m/s and body speed of 1 m/s. Determine the lubricant film thickness.(6 marks) 2 (b) Prove that streamlines and equipotential lines are orthogonal to each other.(6 marks)

### Answer any one question from Q3 and Q4

3 (a) Derive an expression for Euler's equation along stream-Line(6 marks) 3 (b) Write short notes on:
(i) Hydrodynamically smooth and rough boundaries.
(ii) Velocity profile of Turbulent flow.
(6 marks)
4 (a) What is Pitot tube? Derive expression for velocity. Draw with all labels Pitot static tube.(6 marks) 4 (b) Derive expression for velocity distribution for flow in fixed parallel plates.(6 marks)

### Answer any one question from Q5 and Q6

5 (a) Derive an expression for Darcy-Weisbach equation.(6 marks) 5 (b) Discharge Q of a centrifugal pump can be assumed to be dependent on density of liquid ρ, viscosity of liquid μ, pressure p, impeller diameter D, and speed N in RPM. Using Buckingham theorem, show that : $$Q=ND^3 \phi \left [ \dfrac{gH}{N^2D^2}, \dfrac {v}{ND^2} \right ]$$(7 marks) 6 (a) What are repeating variables? What points are important while selecting repeating variables?(6 marks) 6 (b) A siphon of dia. 200 mm connects two reservoirs having a a difference of elevation of 20 m. The total length of siphon is 800m and the summit is 5 m above the water level in the upper reservoir. If separation takes place at 30 kPa (absolute). Find maximum length of siphon from upper reservoir to summit. Take friction factor = 0.016, P atm. = 10.3 m of water.(7 marks)

### Answer any one question from Q7 and Q8

7 (a) Derive an expression for displacement, momentum and energy thicknesses.(9 marks) 7 (b) A car of frontal area 1.4 m2 travels in still air with speed 72 kmph. If drag coefficient is 0.350, calculate power required to drive the car at this speed. Density of air is 1.2 kg/m3.(4 marks) 8 (a) Discuss boundary layer development over flat plate.(7 marks) 8 (b) Write a short note on 'Flow around cylinder and aerofoil'.(6 marks)