Rr220103-hydraulics-and-hydraulic-machinery

Set No. 1

Code No: RR220103

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) What do you mean by most economical section of a channel. What are the conditions for the rectangular channel of the best section? (b) Determine the dimensions of the most economical trapezoidal earth-lined channel (Manning-s n = 0.02) to carry 14 m3 /s at a slope of 4 in 10,000. [8+8] 2. (a) What is a current meter and what are its types. Discuss how can it be used for determining the discharge in a shallow river and in a wider river. (b) Explain the extension and adjustment of stage - Discharge rating curve with a neat sketch. [8+8] 3. Obtain an expression for the depth after the hydraulic jump and the loss of head due to the jump. Write the assumptions made. [16] 4. Prove that the resistance F of a sphere of diameter d moving at a constant speed ν through h ia fluid of density ρ and dynamic viscosity µ may be expressed as F = µ2 [16] φ vdρ ρ µ 5. (a) Show that the efficiency of free jet striking normally on a series of flat plates mountedon the periphery of a wheel can never exceed 50%. (b) A jet of water of diameter 50mm moving with a velocity of 40m/sec, strikes a curved fixed symmetrical plate at the center. Find the force exerted by the jet of water in the direction of the jet, if the jet is deflected through an angle of 1200 at the outlet of the curved plate. [8+8] 6. (a) Write a detailed note on efficiencies of turbine. (b) A turbine is to operate under a head of 30m and a speed of 300 rpm. The discharge is 10 cumecs. If the efficiency of the turbine is 90%, determine [7+9] i. The specific speed of the turbine ii. Power generated and iii. Type of turbine. 7. (a) Tests were conducted on a Francis turbine of 0.8m diameter under a head of 9m. The turbine developed 115 KW running at 240 rpm and consuming 1.2 m3 /sec. If the same turbine is operated under a head of 16m predict its new speed, discharge and power. (b) What are the requirements of a governor in hydropower Installation? [10+6]

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Set No. 1

Code No: RR220103

8. (a) Draw a typical layout and explain the working of centrifugal pump. Also indicate various components. (b) Explain the method of selection of centrifugal pumps through the characteristic curves. [8+8] ⋆⋆⋆⋆⋆

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Set No. 2

Code No: RR220103

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) What do you mean by most economical section of a channel. What are the conditions for the rectangular channel of the best section? (b) Determine the dimensions of the most economical trapezoidal earth-lined channel (Manning-s n = 0.02) to carry 14 m3 /s at a slope of 4 in 10,000. [8+8] 2. (a) Show that the discharge formula for a trapezoidal channel having Manning?s coefficient n = 0.0126 and carrying maximum flow is given by : √ z  1/2 Q = 100y8/3 1 + z 2 − S0 2 Where Q is discharge in cubic meters per second, y is depth of flow in the channel of side slope 1 vertical to Z horizontal and S0 is the bed slope of the channel. (b) A field drain of triangular section has side slopes of 1 upon 2 and carries water at a normal depth of 0.75m. Chezy’s C for the channel is 45. Determine the longitudinal slope of the drain for a discharge of 1.2 cumecs. Determine the Froude number and identify the state of flow. Assume α= 1.16. [8+8] 3. Water flows at a steady and uniform depth of 2 m in an open channel of rectangular cross - section having base width equal to 5 m and laid at a slope of 1 in 100. It is desired to obtain critical flow in the channel by providing a hump in the bed. Calculate hump height and sketch the flow profile. Consider the value of Mannings rugosity coefficient n = 0.02 for the channel surface. [16] 4. (a) State whether the following equations are dimensionally homogeneous. i. Q = Πdbv √ ii. Q = Cd a 2gh √ iii. Q = Ac mi (b) What are the fields of application of Froude‘s Law and Mach Law?

[6+10]

5. A jet of water moving at 12m/sec impinges on vane shaped to deflect the jet through 1200 when stationary. If the vane is moving at 5m/sec, find the angle of the jet so that there is no shock at inlet. What is the absolute velocity of the jet at exit in magnitude and direction and the work done per second? Assume that the vane is smooth. [16] 6. A Pelton wheel is required to develop 12000 kw when working under a head of 300m. It rotates at a speed of 540 rpm. Assuming the jet ratio as 10 and overall efficiency as 84%, calculate: [16] 1 of 2

Set No. 2

Code No: RR220103 (a) The diameter of the wheel (b) The quantities of water required and (c) The number of jets.

7. (a) What are the requirements of a good surge tank so that the efficiency of hydropower installation is maximum? (b) How is the Kaplan turbine governed? Explain with a neat diagram.

[8+8]

8. (a) Draw typical characteristic curves for a centrifugal pump at constant speed and explain how the specific speed is determined from these curves. (b) The impeller of a centrifugal pump has 1.2m outside diameter. It is used to lift 1.8 m3 /s of water to a height of 6m. Its blades make an angle of 1500 with the direction of motion at outlet and runs at 200 rpm. If the radial velocity of flow at outlet is 2.5m/s, find the useful H.P and efficiency. [8+8] ⋆⋆⋆⋆⋆

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Set No. 3

Code No: RR220103

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Derive the condition for depth of flow of a most economical circular channel section subject to the condition for maximum velocity. (b) Water flows in a channel of the shape of isosceles triangle of bed width ‘a’and sides making an. angle of 450 with the bed. Determine the relation between depth of flow d., and the bed width ‘a’ for maximum velocity and for maximum discharge condition. Use Manning’s formula and note that d is less than 0.5 a. [8+8] 2. (a) What are the factors that influence the selection of a site for a stream gauging station. (b) Following velocities were recorded in a stream with a current meter. Depth above bed (m) 0 1 2 3 4 Velocity (m/sec) 0 0.5 0.7 0.8 0.8 Find the discharge per unit width of stream near the point of measurement. Depth of flow at the point was 5m. [8+8] 3. Water flows at a steady and uniform depth of 2 m in an open channel of rectangular cross - section having base width equal to 5 m and laid at a slope of 1 in 100. It is desired to obtain critical flow in the channel by providing a hump in the bed. Calculate hump height and sketch the flow profile. Consider the value of Mannings rugosity coefficient n = 0.02 for the channel surface. [16] 4. Using Buckingham‘s Pi theorem show that velocity through a circular orifice is i h √ µ D [16] given by: V = 2gH φ H , ρV H 5. (a) Define the term: impact of jets. Obtain an expression for the force exerted by a jet of water on a fixed vertical plate in the direction of the jet. (b) Find the force exerted by a jet of water of diameter 100mm on a stationary flat plate, when the jet strikes the plate normally with a velocity of 30m/sec. [8+8] 6. (a) Write a detailed note on efficiencies of turbine. (b) A turbine is to operate under a head of 30m and a speed of 300 rpm. The discharge is 10 cumecs. If the efficiency of the turbine is 90%, determine [7+9] i. The specific speed of the turbine ii. Power generated and 1 of 2

Set No. 3

Code No: RR220103 iii. Type of turbine.

7. (a) Where is servo meter used in governing mechanism of turbines? Explain its use? (b) A Kaplan turbine is to develop 2400 KW when running at 240 rpm under a net head of 49m. In order to predict its performance a model of scale 1:5 is tested under a net head of 25m. At what speed should the model run and what power would it develop. Determine the discharge in the model and in full scale turbine if the overall efficiency of the model is 85%. [6+10] 8. (a) How are pumps classified ? Quote the approximate values of specific speed for different types. (b) Discuss in general the main and operating characteristics of a centrifugal pump? What is the importance of constant efficiency curves ? [8+8] ⋆⋆⋆⋆⋆

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Set No. 4

Code No: RR220103

II B.Tech II Semester Supplimentary Examinations, Aug/Sep 2008 HYDRAULICS AND HYDRAULIC MACHINERY (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ⋆⋆⋆⋆⋆ 1. (a) Derive an expression for the discharge through a channel by Chezy‘s formula. (b) Determine the dimensions of the most economical trapezoidal earth lined Channel (Manning‘s n = 0.020) to carry 14 m3 /s at a slope of 4 in 10,000. [8+8] 2. (a) Discuss the significance and utility of the concept of the specific energy in the study of open channel problems. (b) In a rectangular channel 3.5 m wide laid at a slope of 0.0036, uniform flow occurs at a depth of 2 m. Find how high can the jump be raised without causing afflux? If the upstream depth of flow is to be raised to 2.5 m, what should be the height of the jump? Take Manning?s n equal to 0.015. [8+8] 3. Water flows at a steady and uniform depth of 2 m in an open channel of rectangular cross - section having base width equal to 5 m and laid at a slope of 1 in 100. It is desired to obtain critical flow in the channel by providing a hump in the bed. Calculate hump height and sketch the flow profile. Consider the value of Mannings rugosity coefficient n = 0.02 for the channel surface. [16] 4. (a) What do you mean by model testing ? What are pre requisites for model testing? (b) Properties of a structure can be calculated by analytical method and by model analysis, which is more suitable?. Why? [8+8] 5. (a) Define the term: impact of jets. Obtain an expression for the force exerted by a jet of water on a fixed vertical plate in the direction of the jet. (b) Find the force exerted by a jet of water of diameter 100mm on a stationary flat plate, when the jet strikes the plate normally with a velocity of 30m/sec. [8+8] 6. Design a Pelton wheel for the following data: (a) Gross head available = 170m (b) Losses in penstock = 10% of gross head (c) Power to be developed = 600 kw. (d) Speed of the wheel = 360rpm (e) Overall efficiency = 86%. Assume any missing data suitably.

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[16]

Set No. 4

Code No: RR220103

7. (a) A hydraulic turbine develops 120 KW under a head of 10 m at a speed of 90 rpm and gives an efficiency of 92%. Find the water consumption and the specific speed. If a model of scale 1: 30 is constructed to operate under a head of 8m what must be its speed, power and water consumption to run under the conditions similar to prototype. (b) What are the constant head characteristic curves of a turbine? What is the use to develop them? [10+6] 8. (a) Define specific speed of a centrifugal pump. What is its significance. (b) A centrifugal pump discharges 1200 lit/minute against a head of 16.5 m when the speed is 1500 rpm. The diameter of the impeller is 35 cm and the power required is 6 h.p. A geometrically similar pump of 45 cm is to run at 1750 rpm. Assuming equal efficiencies, find [8+8] i. the head developed ii. the discharge and iii. power developed by the 45 cm pump. ⋆⋆⋆⋆⋆

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