# Sathyabama University 2008 B.E Civil Engineering Mechanics of Fluids - II - Question Paper

**SATHYABAMA****
UNIVERSITY**

**(Established under section 3 of UGC Act, 1956)**

Course & Branch: B.E - CIVIL (Part Time)

Title of the paper: Mechanics of Fluids - II

Semester: II Max. Marks: 80

Sub.Code: 620PT202 (2007/2007 JAN) Time: 3 Hours

Date: 14-05-2008 Session: FN

PART A (10 x 2 = 20)

Answer All the Questions

1. Explain the term dimensionally homogeneous equation.

2. State Buckinghams p - theorem.

3. What do you understand by the terms boundary layer and boundary layer theory?

4. What are the different methods of preventing separation of boundary layers?

5. Define the terms: Hydraulic gradient line and Total energy line.

6. Differentiate between major loss and minor loss in pipes.

7. Differentiate between laminar and turbulent flow.

8. Explain the terms: hydraulic mean depth and wetted perimeter.

9. Differentiate between turbines and pumps.

10. What is priming? Why it is necessary?

PART B (5 x 12 = 60)

Answer All the Questions

11. The variables controlling the motion of a floating vessel through water are the drag force F, the speed V, the length L, the density r, the dynamic viscosity m and the acceleration due to gravity g. Derive an expression for F by dimensional analysis.

(or)

12. A 1:20 model of a flying boat is towed through
water. The prototype is moving in sea-water of density 1024kg/m^{3} at
a velocity of 15m/s. Find the corresponding speed of the model. Also determine
the resistance due to waves on model, if the resistance due to waves of
prototype is 500N.

13. (a) What do you mean by boundary layer separation?

(b) What is the effect of pressure gradient on
boundary layer

separation?

(or)

14. A thin plate is moving in still atmospheric air at
a velocity of 4m/s. The length of the plate is 0.5m and width 0.4m. Calculate
the thickness of the boundary layer at the end of the plate and drag force on
one side of the plate. Take density of air as 1.25kg/m^{3} and
kinematic viscosity 0.15 strokes.

15. Find the diameter of a pipe of length 2500m when
the rate of flow of water through the pipe is 0.25m^{3}/s and head lost
due to friction is 5m. Take C = 50 in Chezys formula.

(or)

16. A horizontal pipe of diameter 400mm is suddenly
contracted to a diameter 200mm. The pressure intensities in the larger and
smaller pipe are given as 14.715N/cm^{2} and 12.73N/cm^{2}
respectively. If C_{c} = 0.62, find the loss of head due to
contraction. Also determine the rate of flow of water.

17. Find the discharge through a rectangular channel 3m wide, having depth of water 2m, and bed slope as 1 in 1500. Take the value of K = 2.36 in Bazins formula, and N = 0.012 in Mannings formula.

(or)

18. The discharge of water through a rectangular
channel of width 6m, is 18m^{3}/s when depth of flow of water is 2m.
Calculate: (i) specific energy of the flowing water. (ii) critical
depth and critical velocity and (iii) value of minimum specific energy.

19. Find the rise in pressure in the impeller of a centrifugal pump through which the water is flowing at the rate of 15 litre/s. The internal and the external diameter of the impeller are 20cm and 40cm respectively. The widths of the impeller at the inlet and outlet are 1.6cm and 0.8cm respectively. The pump is running at 1200rpm. The water enters the impeller radially at inlet and impeller vane angle at outlet is 30. Neglect loss through the impeller.

(or)

20. A Kaplan turbine runner is to be designed to develop 7357.5 kW shaft power. The net available head is 10m. Assume that the speed ratio is 0.6. If the overall efficiency is 70% and the diameter of the boss is 0.4 times the runner, find the diameter of the runner, its speed and specific speed.

Earning: Approval pending. |