B.Tech I Sem Supplementary Examinations, Feb-2008
Fluid mechanics and hydraulic machinery
(Electrical & Electronic Engineering)
1. (a) Define Bulk modulus of liquids. Explain a fluid flow problem where it assumes significance.
(b) One cubic meter of a liquid of relative density 0.788 and bulk modulus 1.32MPa is subjected to an increase of pressure of 4.5 N/cm2. Find the change in volume and also the final density of the liquid.
2. (a) Distinguish between:
i. Steady and Un-steady flow.
ii. Uniform and Non-uniform flow.
iii. Compressible and incompressible flow.
(b) A 400 m long pipe has a slope of 1 in 100 and tapers from 1.2 m dia at high end to 0.6 m dia at the low end. The discharge is 100 lit/sec. If the pressure at high end is 100 kN/m2, find the pressure at the low end. Neglect friction.
3. (a) Define Major Energy Loss and Minor Energy Loss.
(b) Briefly explain Hydraulic Gradiant Line and Total Energy Line.
(c) The rate of flow of water through a horizontal pope is 0.3m3/sec. The diameter of the pipe is suddenly enlarged fron 25cm to 50cm. The pressure intensity in the smaller pipe is 1.4Kgf/cm2. Determine loss of head due to sudden enlargement, pressure intensity in the large pipe and power lost due to enlargement.
4. (a) Derive the expressions for force and work done per second by the jet when it strikes a flat vertical plate moving in the direction of the jet and away from the jet.
(b) A jet of water of 75mm diameter strikes a curved vane at its center with a velocity of 20m/sec. The curved vane is moving with a velocity of 8m/sec in the direction of jet. Find the force exerted on the plate in the direction of the jet power and efficiency of the jet. Assume the plate to be smooth.
5. (a) What are the types of hydroelectric power stations? Write about each of them.
(b) At the site where hydroelectric plant is proposed the following details are available. Calculate the power that can be developed. Available head = 28 m
Catchment area = 420 Km2
Yearly rainfall = 140 cm
Rainfall utilization rate = 68%
Penstock efficiency = 94%
Turbine efficiency = 80%
Generator efficiency = 84%
6. (a) How does the Kaplan turbine get its name ? Explain its construction and working.
(b) Explain different efficiencies and working proportions of a Kaplan turbine in detail ?
7. (a) What is a surge tank ? What are its uses in a hydraulic turbine installation ?
(b) A hydropower plant has to work under the following conditions. Determine the likely number of turbines of specific speed 120 for the plant.
Net head = 20m,
Speed = 300 rpm,
Discharge = 6 m3/sec,
Hydraulic efficiency = 97%,
Volumetric efficiency = 98%
Mechanical efficiency = 92 %.
8. (a) Define slip and coefficient of discharge of a reciprocating pump and write the expressions for the same. What do they practically indicate?
(b) The following details refer to working of a single acting reciprocating pump. Find the slip, coefficient of discharge and theoretical power required to drive the pump.
Piston diameter = 15 cm
Crank radius = 15 cm
Diameter of delivery pipe = 10 cm
Discharge of the pump = 0.31 m3 /min
Total lift = 15 m
Speed of the pump = 60 rpm