8/14/2019 e310 Fluid Mechanics and Hydraulic Machinery Set1 (2)

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Code No: E310 OR

II B.Tech.(CCC) Supplimentary Examinations, December 2008FLUID MECHANICS AND HYDRAULIC MACHINERY

(Civil Engineering)Time: 3 hours Max Marks: 100

Answer any FIVE QuestionsAll Questions carry equal marks

1. (a) Explain the following terms:

i. Force of buoyancy and center of buoyancy.

ii. Metacentre and metacentric height.

iii. Stable, unstable and neutral equilibrium. [10]

(b) A solid cylinder of diameter 4.0 m has a height of 3 meters. Find the meta-centric height of the cylinder when it is floating in water with its axis vertical.The specific gravity of the cylinder is 0.6. [10]

2. (a) Define and distinguish between

i. Steady and unsteady flow,

ii. Uniform and non uniform flow,

iii. Rotational and irrotational flow. [12]

(b) Define and distinguish between streamline, path line and streak line. [8]

3. (a) What do you mean by most economical section of a channel. What are theconditions for the rectangular channel of the best section? [10]

(b) Derive the Chezys formula for finding discharge through openchannel. [10]

4. Using Buckingham -theorem, show that the velocity through a circular orifice is

given by V=

2gH DH

, V H

, where H is the head causing flow, D is the diameter

of the orifice, is co-efficient of viscosity,is the mass density and g is the accelerationdue to gravity. [20]

5. (a) What do you mean by boundary layer separation? What is the effect ofpressure gradient on boundary layer separation? [10]

(b) What do you understand by total drag on a body, resultant force on a body,co-efficient of drag and co-efficient of lift. [10]

6. Show that the efficiency of a free jet striking normally as series of flat platedmounted on the periphery of a wheel never exceeds 50% . [20]

7. A double jet Pelton wheel is required to generate 7500 K.W. when the availablehead at the base of the nozzle is 350 m. The jet is deflected through 1500 and

the relative velocity of the jet is reduced by 15% in passing over the buckets.Determine

(a) the diameter of each jet,

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8/14/2019 e310 Fluid Mechanics and Hydraulic Machinery Set1 (2)

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Code No: E310 OR

(b) Total flow,

(c) Force exerted by the jet on buckets in tangential direction.

Assume generator efficiency of 85% , Overall efficiency of 80% , Coefficient of ve-locity = 0.97 and speed ratio = 0.46. [20]

8. (a) Differentiate between specific speed and suction specific speed of a centrifugalpump. [8]

(b) A centrifugal pump discharges 20 lit/sec against a head of 16.5 m when thespeed is 1500 rpm. The diameter of the impeller is 35 cm and the powerrequired is 6 h.p. A geometrically similar pump of 45 cm is to run at 1750rpm. Assuming equal efficiencies, find

i. the head developed

ii. the discharge and

iii. power developed by the 45 cm pump. [12]

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