Code No: R05310302 Set No. 1 III B.Tech I Semester Regular Examinations, November 2007 HYDRAULIC MACHINERY AND SYSTEMS ( Common to Mechanical Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. A jet of water coming out of nozzle at a velocity of 35m/sec strikes a series of vanes without shock which are moving with a velocity of 10m/sec. The direction of jet is 20 0 to the motion of vanes. The relative velocity of jet at outlet is 0.9 times relative velocity at inlet. The absolute velocity of jet at outlet is normal to the motion of vanes. Find (a) the inlet and exit vane angles, (b) work done (c) Efficiency of the system. [16] 2. A water tube has a velocity of 4m/sec at the entrance to the draft tube and a velocity of 1.2m/sec at the exit. For Friction losses of 0.1m and a tail water 5m below the entrance to the draft tube, find the pressure head at the entrance. [16] 3. (a) What is meant by cavitation? What is Thomas cavitation factor and what is its significance for water turbines. (b) Explain Iso-efficiency curves. [8+8] 4. (a) Why is the speed of a reciprocating pump lower than that of a centrifugal pump? On what factors does the speed of the reciprocating pump depend? (b) Explain how the separation of flow is caused in reciprocating pumps. What preventive measures are usually taken to reduce the same appreciably? [8+8] 5. (a) How will you obtain an expression for the minimum speed for starting a centrifugal pump? (b) The internal and external diameter of the impeller of a centrifugal pump are 200 mm and 400 mm respectively. The pump is running at 1200 r.p.m. the vane angles of the impeller at inlet and outlet are 20 o and 30 o respectively. The water enters the impeller radially and velocity of flow is constant. Determine the work done by the impeller per unit weight of water. [6+10] 6. (a) What do you understand by characteristic curves of a pump? What is the significance of the characteristic curves. (b) Find the number of pumps required to take water from a deep well under a total head of 89 m. All the pumps are identical and are running at 800 r.p.m. the specific speed of each pump is given as 25 while the rated capacity of each pump is 0.16 m 3 /s. [8+8] 1 of 2
Code No: R05310302 Set No. 1 7. The diameter of ram of a jigger of the crane is 30 cm and velocity ratio of the crane is 5 : 1. the length of supply pipe from accumulator = 150 m and its diameter is 5 cm. the pressure in the accumulator = 54 bar. Friction on ram and pulley is equivalent to a pressure of 4.9 bar. Take f = 0.01. Find the relation between the load W (kn) lifted and speed of lifting V (m/s). Find V when W = 50 kn. [16] 8. (a) A pipe of diameter 300 mm and length 3500 m is used for the transmission of power by water. The total head at the inlet of the pipe is 500 m. Find the maximum power available at the outlet of the pipe, if the value of f=0.006. (b) A nozzle is fitted at the end of a pipe of length 300 m and of diameter 100 mm. For the maximum transmission of power through the nozzle, find the diameter of nozzle. Take f = 0.009. [8+8] 2 of 2
Code No: R05310302 Set No. 2 III B.Tech I Semester Regular Examinations, November 2007 HYDRAULIC MACHINERY AND SYSTEMS ( Common to Mechanical Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. (a) Find an expression for the efficiency of a series of moving curved vanes when a jet of water strikes the vanes at one of its tips. (b) A jet of water of diameter 65 mm moving with a velocity of 30m/s, strikes a curved fixed plate tangentially at one end at an angle of 30 0 to the horizontal. The jet leaves the plate at an angle of 18 0 to the horizontal. Find the force exerted by the jet on the plate in the horizontal and vertical directions. [8+8] 2. An inward flow reaction turbine has outer and inner diameters of the wheel as 1 m and 0.5 m respectively. The vanes are radial at inlet and the discharge is radial. Water enters the vanes at an angle of 10 0. Assuming the velocity of flow as 3 m/s and constant, find the speed of the wheel and the vane angle at outlet. [16] 3. Define cavitation. What factors affect occurrence of cavitation in turbines. What measures are to be taken to prevent it? If cavitation were to occur, at what locations the cavitation damage is likely to take place. [16] 4. Derive expressions for the accelerations and friction head impressed on the water in the suction and delivery pipes. Sketch indicator diagram and determine the work done per stroke of the pump. [16] 5. (a) What do you mean by manometric efficiency, mechanical efficiency and overall efficiency of a centrifugal pump. (b) A centrifugal pump is to discharge 0.118 m 3 /s at a speed of 1450 r.p.m against a head of 25 m. The impeller diameter is 250 mm, its width at outlet is 50 mm and manometric efficiency is 75%. Determine the vane angles at the outer periphery of the impeller. [8+8] 6. (a) What is cavitation? State its effect on the performance of water turbines and also state how to prevent cavitation in water turbines. (b) Find the rise in pressure in the impeller of a centrifugal pump through which water is flowing at the rate of 0.01 m 3 /s. The internal and external diameter of the impeller are 15 cm and 30 cm respectively. The widths of the impeller at inlet and outlet are 1.2 cm and 0.6 cm. The pump is running at 1500 r.p.m. The water enters the impeller radially at inlet and impeller vane angle at outlet is 45 o. Neglect losses through the impeller. [6+10] 7. (a) A hydraulic lift is required to lift a load of 98.1kN through a height of 12 m, once in every 100 seconds. The speed of the lift is 600 mm/s. Determine: 1 of 2
Code No: R05310302 Set No. 2 i. power required to drive the lift, ii. working period of lift in seconds, and iii. idle period of the lift in seconds. (b) What is hydraulic intensifier? Explain its principle and working. [10+6] 8. (a) A pipe of diameter 300 mm and length 3500 m is used for the transmission of power by water. The total head at the inlet of the pipe is 500 m. Find the maximum power available at the outlet of the pipe, if the value of f=0.006. (b) A nozzle is fitted at the end of a pipe of length 300 m and of diameter 100 mm. For the maximum transmission of power through the nozzle, find the diameter of nozzle. Take f = 0.009. [8+8] 2 of 2
Code No: R05310302 Set No. 3 III B.Tech I Semester Regular Examinations, November 2007 HYDRAULIC MACHINERY AND SYSTEMS ( Common to Mechanical Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. 5 cm diameter jet having a velocity of 20m/sec, strikes a flat plate, the normal of which is inclined at 25 0 to the axis of the jet. Calculate the normal force exerted on the plate (a) When the plate is stationary (b) When the plate is moving with a velocity of 10m/sec in the direction of the jet. (c) When the plate is moving with a velocity of 7m/sec parallel to itself and in the direction of the normal to its surface. [4+6+6] 2. Obtain an expression for the work done per second by water on the runner of a Pelton wheel. Hence derive an expression for maximum efficiency of the Pelton wheel giving the relationship between the jet speed and the bucket speed. [16] 3. (a) Define Suction Specific Speed. Explain the procedure for the selection of type of turbine runner. (b) List out different types of surge tanks and explain any two along with neat sketches. [8+8] 4. A double acting reciprocating pump has a stroke of 250mm and plunger diameter 125 mm. The center of the pump is 4 m above the lower sump water level and 30 m below the delivery water. The lengths of suction and delivery pipes are 6 m and 35 m respectively. Both pipes are 60 mm in diameter. If the pump is to run at 30 rpm, find the pressure head on the piston, at the beginning, middle and end of the suction stroke. If mechanical efficiency is 75% and f=0.04, determine the power required to drive the pump. [16] 5. The outer diameter of an impeller of a centrifugal pump is 400 mm and outlet width 50 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 40 o and manometric efficiency is 75%. Determine: (a) velocity of flow at outlet (b) velocity of water leaving the vane, (c) angle made by the absolute velocity at outlet with the direction of motion at outlet, and (d) discharge. [16] 1 of 2
Code No: R05310302 Set No. 3 6. (a) Draw and discuss the operating charecteristcs of a centrifugal pump. (b) Two geometrically similar pumps are running at the same speed of 1000 r.p.m. One pump has an impeller diameter of 0.3 meter and lifts water at the rate of 20 liters per second against a head of 15 meters. Determine the head and impeller diameter of the other pump to deliver half the discharge. [6+10] 7. (a) How does a torque convertor differ from a fluid coupling? Explain the working principle of any one of them. (b) A hydraulic lift is required to lift a load of 8 kn through a height of 10 meters, once in every 80 seconds. The speed of the lift is 0.5 m per second. Determine: i. Power required to drive the lift, ii. Working period of lift in seconds, and iii. Idle period of the lift in seconds. [8+8] 8. (a) A pipe of diameter 300 mm and length 3500 m is used for the transmission of power by water. The total head at the inlet of the pipe is 500 m. Find the maximum power available at the outlet of the pipe, if the value of f=0.006. (b) A nozzle is fitted at the end of a pipe of length 300 m and of diameter 100 mm. For the maximum transmission of power through the nozzle, find the diameter of nozzle. Take f = 0.009. [8+8] 2 of 2
Code No: R05310302 Set No. 4 III B.Tech I Semester Regular Examinations, November 2007 HYDRAULIC MACHINERY AND SYSTEMS ( Common to Mechanical Engineering and Automobile Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks 1. (a) Show that the force exerted by a jet of water on moving inclined plate in the direction of jet is given by F x = ρa (V u) 2 sin 2 θ, where a=area of the jet, θ=inclination of the plate with the jet, V=velocity of jet, u=velocity of plate (b) A jet of water of diameter 100mm moving with a velocity of 25m/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 120 0 at the outlet of the curved plate. [8+8] 2. (a) Draw a neat diagram of a reaction turbine and explain its working. State the equations for power produced and efficiency. (b) Explain any two types of draft tubes with neat diagrams. [8+8] 3. What do you understand by characteristic curves of a turbine? Explain various types of characteristic curves of a turbine along with neat sketches. [16] 4. (a) List out eight differences between centrifugal pumps and reciprocating pumps. (b) Differentiate between i. single acting and double acting reciprocating pump ii. single cylinder and double cylinder reciprocating pump. [8+8] 5. (a) What do you mean by manometric efficiency, mechanical efficiency and overall efficiency of a centrifugal pump. (b) The diameters of an impeller of a centrifugal pump at inlet and outlet are 20 cm and 40 cm respectively. Determine the minimum speed for starting the pump if it works against head of 25 m. [8+8] 6. A one-fifth scale model of pump was tested in a laboratory at 1000 r.p.m. the head developed and power input at the best efficiency point were found to be 8 m and 30 kw respectively. If the prototype pump has to work against a head of 25 m, determine its working speed, the power required to drive it and the ratio of the flow rates handled by the two pumps. [16] 7. (a) Water at a pressure of 8 bar is supplied to a crane for lifting a weight through a height of 8 m. The diameter of the ram is 16 cm and velocity ratio 5. Assuming the efficiency of the crane 70%, find: i. The weight lifted by the crane, and ii. Volume of water supplied to the crane. 1 of 2
Code No: R05310302 Set No. 4 (b) Draw a neat diagram of a hydraulic press and explain its working. [8+8] 8. (a) A pipe line is 30 cm in diameter for first 1000 m. length and 15 cm diameter for next 1000 m. Find the discharge from the system for transmitting maximum power. Total pressure at the intake 5.5 kn/m 2. Take f = 0.008 for both pipes. (b) Determine the maximum power available at the exit of the pipe of 30 cm diameter and 3500 m long. The head at the inlet is 500m. Take f = 0.006. [8+8] 2 of 2