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Code No: X0222

II B.Tech I Semester (R07) Regular Examinations, Nov- 2009

FLUID MECHANICS AND HYDRAULIC MACHINERY

(Electrical and Electronics Engineering)

Time: 3 hours Max Marks: 80Answer any FIVE Questions

All Questions carry equal marks

1. a)StateNewtons law of viscosity. What is the effect of temperature on viscosity ofvarious fluids?

b)A cylinder of 0.30m diameter rotates concentrically inside a fixed cylinder of 0.31m

diameter. Both the cylinders are 0.3m long. Determine the viscosity of the liquid whichfills the space between the cylinders if a torque of 0.98N-m is required to maintain an

angular velocity of 2 rad/s. [8+8]

2. a)Define streamline, streak line and a path lineb) The stream function for a particular flow is = x

3

y3

. Show that the flow cannot be a potential flow.

3. a) List out the minor losses in closed conduit flow and discuss their significance[6]

b) A 6 cm diameter pipe has a discharge of 450 lit/min. At a section the pipe has a sudden

expansion to a sixe of 9 cm diameter. If the pressure just upstream of the expansion is 20kN/ m2, calculate the pressure just after the expansion. Assume the pipe to be horizontal

[10]

4. a)A jet of water 75mm in diameter issues with a velocity of 30m/sec and impinges on astationary flat plate normally. Find the force exerted by the jet on the plate.

[8]

b) Find the impact of jet striking a normal flat plate when the plate is stationary [8]

5. a) Give different classification of hydro electric power plants and explain at least two power plants with neat sketches. [8]

b)Explain in detail mini and micro hydropower plants. [8]6. a) Differentiate between inward and outward flow reaction turbines [8]

b) Design a Francis turbine having radial blades with width to diameter ratio at inlet and

outlet as 0.5 and 0.7 respectively. Head of 70m, speed 500rpm, brake power 300kW,

flow ratio 0.2, speed ratio 0.7, hydraulic efficiency 95% and overall efficiency 85%.

[8]7. a) Explain unit speed, unit power and unit discharge. (6)

(b) Tests were conducted on a Francis turbine of 0.8 m diameter under a head of 9 m. Theturbine running at 240 r.p.m. developed 84.5 kW and the water consumption was 1.2

m3/s. If the same turbine is operated under a head of 16 m, predict its new speed,

discharge and power developed. (10)

8. Explain with neat sketches the working of a single- stage centrifugal pump. (16)1 of 1

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1. a)Classify fluids. What are the various properties of fluids? [6+10]b)A cylinder of diameter 0.1m rotates in an annular sleeve of internal diameter 0.102m at

100rpm. The cylinder is 0.25m long. If the dynamic viscosity of the lubricant between the two

cylinders is 0.9 paise, find the torque needed to drive the cylinder against viscous resistance.

2. a)Define path line, streak line and the streamline. For what type of flow these lines areidentical? [8+8]

b)A two-dimensional flow field is given by = 3xy. Determine the stream function. Determine

the velocities at A(1,2) and B(2,2). What is the discharge between the streamlines passing

through these points?

3. a) Describe the Reynolds experiment with the help of a neat sketch. [6]b) Two reservoirs with a difference in water surface elevations of 10m are connected by a pipe

line ABC which consists of two pipes of AB and BC joined in series. Pipe AB is 10cm in diameter,

20m long and has a value of f =0.02. Pipe BC is of 16cm diameter, 25m long and has f=0.018. The

junctions with the reservoirs and between the pipes are abrupt. Calculate the dischargeconsidering all minor losses. [10]

4. a)A jet of liquid with specific gravity of 0.85 strikes a fixed flat plate. The diameter of the jet is100 mm and its velocity is 45 cm/sec. Find the force exerted by the jet on the plate [8]

b) Find the impact of jet striking an inclined flat plate when the plate is stationary [8]

5. a)What is the function of draft tube? List various types of draft tubes and explain them withneat sketches [8+8]

b) How a storage tank helps in reducing in water hammer effect? Describe the various types of

surge tanks with necessary sketches.

6. a)A pipeline 1200m long supplies water to 3 single jet Pelton wheels. The head above the nozzleis 360m. The velocity coefficient for the nozzle is 0.98 and the coefficient of friction for thepipeline is 0.02. The turbine efficiency based on the head at the nozzle is 0.85. The specific

speed of each turbine is 15.3 (in m, kW, r.p.m., units) and the head lost due to friction in the

pipeline is 12m of water. If the operating speed of each turbine is 560 r.p.m., determine the

total power, the diameter of each nozzle, the diameter of the pipeline, Volume of water used

per second. (8)

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Code No: X0222

b) A Kaplan turbine produces 60,000 kW under a net head of 25m with an overall efficiency of

90% Taking the value of speed ratio Kuas 1.6, flow ratio as 0.5 and the hub diameter as 0.35

times the outer diameter, find the diameter and speed of the turbine.

(8)

7. What are the characteristic curves of a hydraulic turbine? How are they useful to practicalengineer? (16)

8. The outer diameter of an impeller of centrifugal pump is 400 mm and outlet width50 mm. The pump is running at 800 r.p.m and is working against a total head of

15 m. The vanes angle at outlet is 400 and manometric efficiency is 75%. Determine

(i) velocity of flow at outlet, (ii) velocity of water leaving the vane, and (iii) angle

made by the absolute velocity at outlet with the direction of motion at outlet, and

(iv) discharge. (16)

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Code No: X0222






1. a) Define kinematic and dynamic viscosity. What is the effect of temperature onviscosity? Explain.

b)The space between two parallel plates 5mm apart is filled with an oil of relative density

0.9. A force of 2N is required to drag the upper plate of area 900 cm2

at a constantvelocity of 0.8m/s. Assume straight line velocity distribution and calculate the dynamic

viscosity and kinematic viscosity. [8+8]

2. a) Define stream function. What are the conditions for flow to be irrotational?b)A stream function =2xy. Show that the function satisfies the continuity equation and

that the flow is irrotational. Workout the corresponding velocity potential function[6+10]

3. a)Derive the Darcy Weisbach equation. [6]b) Two reservoirs are connected by a pipe line ABC which consists of two pipes of AB

and BC joined in series. Pipe AB is 10cm in diameter, 20m long and has a value of f

=0.02. Pipe BC is of 16cm diameter, 25m long and has f=0.018. The junctions with thereservoirs and between the pipes are abrupt. What difference in water levels shall exist to

maintain a discharge of 15 lit/sec. [10]

4. a)A jet of water strikes with a velocity of 50 m/sec a flat fixed plate inclined at 30degrees with the axis of the jet. The cross sectional area of the plate is 100 cm

2. Find the

force exerted by the jet on the plate and the ratio in which the jet gets divided after

striking. [8]b) Derive the equation for the impact of jet striking a curved plate at the centre when the plate is stationary.

5. a) Classify the water turbines based on action of water on moving blades and explainthem.b)What are the types of water turbines used in high head hydro electric power plant and

why? Describe the various factors to be considered while selecting a water turbine [6+10]

6. a)The velocity of whirl at inlet to the runner of an inward flow reaction turbine is (3.15H )m/s and the velocity of flow at inlet is (1.05 H )m/s. The velocity of whirl at exit

is (0.22 H )m/s in the same direction as at inlet and the velocity of flow at exit is (0.83H )m/s, where H is the head in meters. The inner diameter of the runner is 0.6 times the

outer diameter. Assuming hydraulic efficiency of 80%, compute the angles of the runner

vanes at inlet and exit. [8]

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b)A reaction turbine works at 450 r.p.m under a head of 120m. Its diameter at inlet is

1.2m and the flow area is 0.4 m2. The angles made by the absolute and relative velocities

at inlet are 20

o

and 60

o

respectively with the tangential velocity. Determine the volumeflow rate, the power developed and the hydraulic efficiency. Assume whirl at outlet to bezero. [8]

7. (a) What is specific speed? State its significance in the study of hydraulic machines. [8](b) A turbine develops 8000 kW when running at 100 r.p.m. The head on the turbine is 30

m. If the head is reduced to 18 m, determine the speed and power developed by the

turbine. [8]

8. Explain the working principles of reciprocating pump with sketches. [16]

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Code No: X0222

6. a) Prove that the maximum efficiency of Pelton wheel occurs when the ratio of bucketvelocity u to the jet velocity V is expressed as = ]

)cos1(2cos1[u

21

1

KKK

V cc

)Where

the loss due to bucket friction and shock is expressed asg

uVK

2

)( 21 and that due to

bearing friction and windage loss as (K2g

u

2

2

);1

K and K2 are constants and being the

bucket angle at outlet.(Neglect volumetric losses) [8]

b)A Pelton wheel has to be designed for the following data: Power to be developed=

6000kW. Net head available = 300 r.p.m.; Ratio of jet diameter to wheel diameter = 1/10;

and overall efficiency = 85%. Find the number of jets; diameter of the jet; diameter ofthe wheel; and the quantity of water required. [8]

7. Define unit speed, unit discharge and unit power of a hydraulic turbine. Explain how aplot of unit power and efficiency against unit speed at different gate openings can be used

to predict the performance of a turbine under any working condition. [16]

8. A single acting reciprocating pump has a 15 cm piston with a crank of radius 15 cm.The delivery pipe is 10 cm diameter. At a speed of 60 r.p.m., 310 litres/s of water is

lifted to a total height of 15 m. Find the slip, coefficient of discharge and theoretical

power in kW required to drive the pump. [16]

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