UNIT I: UNIFORM FLOW PART B

Transcription

1 UNIT I: UNIFORM FLOW PART-A 1 Define open channel flow with example BT Distinguish between open channel flow and pipe flow. BT Compute the hydraulic mean depth of a small channel 1m wide, 0.5m deep BT-5-1 with water flowing at 2m/s. 4 Define uniform flow in channels BT What are the characteristics of open channel flow? BT What are the various types of flow in open channels? BT What are the possible types of flow in open channel with respect to space and BT-2-2 time? 8 State critical flow BT Define the term (i) Gradually varied flow (ii) Rapidly varied flow BT Sketch the velocity distribution in rectangular and triangular channels. BT Define hydraulic mean depth BT List the factors affecting Manning s roughness coefficient BT Write about non erodible channels. What are the factors considered while BT-6-2 designing non-erodible channel. 14 Find the relationship between Chezy's C and Manning's n. BT Describe specific energy? BT Discuss about specific force? BT Distinguish between steady uniform flow and unsteady non uniform flow. BT Write about most economical section? BT Select on what condition most economical trapezoidal channel section is BT-5-2 derived? 20 Write the Bazin s formula for the discharge in the channel. BT-3-3 PART B 1. Write the condition for the most economical trapezoidal channel section BT A trapezoidal channel has side slopes of 1 horizontal to 2 vertical and the slope of the bed is 1 in2000. The area of the section is 42 m 2. Find the dimensions of the section if it is to be most economical. Identify the discharge of the most BT-2-1 economical section of C = The circular sewer 0.6m inner diameter has a slope of 1 in 400. Examine the BT-4-1 depth when the discharge is 0.283m3/sec. Take C= A rectangular channel with a base width of 0.60 m carries a discharge of 100 BT-3-2 lps. The Chezy's C is 60. If the depth of flow is 0.25 m, illustrate the bed slope of the channel 5. Appraise the slope of the channel A V-shapped open channel of included angle BT o conveys a discharge of 0.05m 3 /s when the depth of flow at the center is 0.225m. Assume that C=50 in chezy s equation. 6. Derive chezy s formula for discharge through channel. Write the formula to BT-6-1 find out the constant c

2 7. Define specific energy. How would you express the specific energy for a wide rectangular channel with depth of flow d and velocity of flow v? Draw the typical specific energy diagram and reproduce its features. 8. If y 1 and y 2 are alternate depths in a rectangular channel memorize that y 3 2 c = (2y y / (y1 + y2) and hence the specific energy 2 E = (y + 1 y1y2 + y 2 2 ) / (y1 + y2) 9. A 3m wide rectangular channel conveys 12m 3 of water at a depth of 2m. list 1. Specific energy of flowing fluid. 2. Critical depth, critical velocity and the minimum specific energy. 3. Froude number and state whether the flow is sub-critical or super critical. 10. Calculate the specific energy of 12m 3 /s of water flowing with a velocity of 1.5m/s in a rectangular channel 7.5m wide. Find the depth of water in the channel when the specific energy would be minimum. Identify the value of critical velocity as well as minimum specific energy? BT-1-1 BT-1-2 BT-1-3 BT-2-2 UNIT II: GRADUALLY VARIED FLOW PART A 1. Define varied flow. Explain its classification. BT Distinguish gradually varied flow and rapidly varied flow in open channel. BT List the assumption made in the derivation of dynamic equation for gradually BT-1-9 varied flow 4. Classify the surface profiles in channels, BT Write about backwater curve BT Define draw down curve BT Write the expression to determine the length of the backwater curve. BT What are the flow profile possible un mild sloped channels? BT Distinguish between draw down and back water curves. BT Define spatially varied flow BT What is backwater curve in gradually varied flow profile and give practical BT-6-3 example for getting this type of profile. 12. What are the methods used to determine the length of surface profile? BT If the depth increases in the direction of flow what type of curve is formed? BT State Afflux BT How will do you distinguish between a gradually varied flow and a rapidly BT-4-5 varied flow? 16. Show that maximization of discharge requires minimization of the wetted BT-5-4 perimeter of the channel for a given area of flow. 17. Write down the condition for mild slope and critical slope? BT Explain the normal slope of an open channel? BT Illustrate the methods used to determine the length of surface profile. BT List the classification of spatially varied flow based on discharge? BT-1-8

3 PART B 1. Formulate the dynamic equation for gradually varied flow stating the BT-6-2 assumption made. 2. Discuss the different surface profiles for the various bottom slope condition of BT-2-3 a channels. 3. The bed width of a trapezoidal channel section is 40 m and the side slope is 2 BT-4-2 horizontal to 1 vertical. The discharge in the canal is 60 cumecs. The Manning s n is and the bed slope is 1 in Examine the normal depth. 4. The bed width of a rectangular channel is 24m and the depth of flow is 6m. BT-3-3 The discharge of flow is 6m. The discharge in the channel is 86 cumecs. The bed slope of the channel is 1 in Assume chezy s constant C=60. Illustrate the slope of the free water surface. 5. A river 90m wide and 3m deep has a stable bed banks with a surface slope 1 BT-2-4 in Identify the length of back water curve produced by an afflux of 2m. Assume Manning s N= Derive and write the expression for the length of Backwater Curve. BT State and discuss the assumptions made in the derivation of the dynamic equation for gradually varied flow. Starting from the first principles, derive equations for the slope of the water surface in gradually varied flow with respect to BT-1-5 i. Channel bed ii. Horizontal 8. A rectangular flume is 1.5m wide carries discharge at the rate of 2m 3 /s. The BT-1-4 bed slope of the flume is At a certain section, the depth of flow is 1m. Calculate the distance of the section downstream where the depth of flow is 0.75m. Solve by single slope method. Assuming rugosity coefficient as Is the slope of the channel mild or steep? List this type of surface profile classified? 9. A trapezoidal channel with bed width of 10m and side slopes 1 Vertical : 1.5 BT-5-2 Horizontal is carrying a flow of 80 m 3 /s. The channel bottom slope is and Manning s n is A dam is planned in such a way that the flow depth increases to 10m. Judge the depth of flow in the channel 250m, 500m and 750m upstream of the dam. Use the standard step method. 10. Reproduce and explain the profile determination by numerical method for calculating the length of water surface profile. BT-1-6 UNIT III: RAPIDLY VARIED FLOW PART - A 1 Why momentum equation only used for rapidly varied flow problems. BT Describe the rapidly variedly varied flow with example. BT What are the application of momentum equation for RVF. BT-3-7

4 4 Define critical flow. BT Define critical velocity BT Distinguish between critical,subcritical and super critical flows. BT State the condition for critical and super critical flow BT Define the terms : hydraulic gradient line and total energy line. BT Define afflux BT What is mean by energy dissipation BT Explain the energy loss in a hydraulic jump? BT Distinguish between positive and negative surges BT What is the state of flow after formation of a hydraulic jump? BT Describe the uses of hydraulic jump. BT What is the condition for getting hydraulic jump in open channel? BT What are the classification of hydraulic jump. BT Write about surges? BT Differentiate the positive and negative surges? BT Justify the transition in open channel? BT Write down the application of transition BT-5-6 PART B 1 A trapezoidal channel with a base of 5m side slope of 1.5 horizontal to 1 BT-5-3 vertical conveys water at 16m 3 /s with a depth of 1.2m. Is the flow situation sub or supercritical? 2. In a rectangular channel of bed width 0.5 m, a hydraulic jump occurs at a BT-2-5 point where depth of flow is 0.15 m and Froude s number is 2.5. Locate (1) The specific energy (2) The critical depth (3) The subsequent depths (4) Loss of head (5) Energy dissipated. 3. Froude number before the jump is in a hydraulic jump occurring in a BT-2-6 rectangular channel and the energy loss is 3.20m. Discuss the (i) Sequent depths and (ii)the discharge. 4. A spillway discharges a flood flow at a rate of 7.75 m 3 /s per metre width. At BT-4-3 the downstream horizontal apron the depth of flow was found to be 0.5 m. What tail water depth is needed to form a hydraulic jump? If a jump is formed, examine its type, length, head loss and energy loss as a percentage of the initial energy. 5. The depth of flow of water at a certain section of rectangular channel 2m wide BT-3-5 is 0.25m. the discharge through the channel is 1.8m 3 /s. Demonstrate whether a hydraulic jump will occur and if so, determine its height and loss of energy per kg of water. 6. Write the expression for depth of hydraulic jump. BT During an experiment conducted on a hydraulic jump, in a rectangular open channel 0.5m wide, the depth of water changes from 0.2m to 0.5m. List the discharge in the channel and the loss of head due to the formation of hydraulic jump. BT-1-7

5 8. Solve the slope of the free water surface of a rectangular stream 7.5m wide and 2.5m deep. The slope of the stream bed is 1 in Total discharge is 15m 3 /s. assume C=62 and the depth is increasing in the direction of flow. 9. (i) A rectangular channel carries a flow with a velocity of 0.65m/s and depth of 1.4m. If the discharge is abruptly increased three fold by sudden lifting of a gate on the upstream side, list the following, (i)velocity and height of the resulting surge? (ii)with neat diagrams explain different types of channel transitions. 10. (i) list the classification of hydraulic jumps. (ii)explain with a neat diagram the surges produced when (a) a sluice gate is suddenly raised (b) sluice gate is suddenly lowered. BT-3-6 BT-1-8 BT-1-9 UNIT IV: TURBINES PART A 1 What is hydraulic turbine? BT What are the applications of momentum principle? BT What are the components of energy transfer in turbo machines? BT Classify hydraulic turbines? BT Differentiate the impulse and reaction turbine. BT Describe the impulse turbine with example. BT What is reaction turbine? Give example. BT State radial flow turbine. BT Differentiate the inward flow reaction turbine and outward flow reaction BT-4-12 turbine. 10 What is the purpose of providing casing in turbine? BT Why draft tubes not used in impulse turbines? BT Draw typical velocity triangles for inlet and outlet of pelton wheel. BT Define hydraulic efficiency BT What is overall efficiency in turbines? BT Write the function of draft tube in turbine outlet. BT Write the types of draft tube. BT Define cavitation BT What are the uses of draft tubes BT Define specific speed of a turbine. BT Write about governing of turbines? BT-6-1 PART B 1 A Pelton wheel operates with a jet of jet of 200 mm diameter under the head of 600 m, its mean runner diameter is 2.5 m and it runs with a speed of 400 rpm. The angle of bucket tip at outlet as 15º, coefficient of velocity is 0.99, mechanical losses equal to 4% of power supplied and the reduction in relative BT-1-10

6 velocity of water while passing through bucket is 20%. List the following (i) the force of jet on the bucket (ii) the power developed (iii) bucket efficiency and (iv) overall efficiency. 2 A Pelton turbine is required to develop 9000 kw when working under a head of 300 m. The runner may rotate at 500 rpm. Assuming the jet ratio as 10, speed ratio as 0.46 and overall efficiency as 85%, list the following: i. Quantity of water required ii. Diameter of the wheel iii. Number of jets iv. Number of buckets. 3 A Pelton wheel generates 8000 kw under a net head of 130 m at a speed of 200 rpm. Assuming the coefficient of velocity for the nozzle 0.98, hydraulic efficiency 87%, speed ratio 0.46 and jet diameter to wheel diameter ratio 1/9, identify (i) Discharge required (ii) Diameter of the wheel (iii) Diameter and number of jets required and (iv) Specific speed of the turbine. Take Mechanical efficiency is 75%. 4 Reproduce the impulse momentum principle. What are the various application of momentum principle explain? 5 (i)classify the turbines based on : 1. Action of water on turbine blades. 2. Head on turbine. 3. Direction of flow through turbine runner. 4. Specific speed. 5. Disposition of turbines shaft. (ii) Distinguish between impulse turbine and reaction turbine. 6 A impulse wheel has a mean bucket speed of 10m/s with a jet of water flowing at the rate of 1m 3 /s under a head of 50m. The buckets deflect the jet through an angle 165 o. Employ the power given by water to runner and the hydraulic efficiency of turbine. Assume the coefficient of velocity as In an inward flow reaction turbine, head on turbine is 32 m. The external an internal diameters are 0.44 m and 0.72 m respectively. The velocity of flow through the runner is constant and equal to 3 m/s. The guide blade angle is 10º and runner vanes are rigid at inlet. If the discharge at outlet is radial, list the following (i) The speed of the turbine (ii) The vane angle at outlet of the runner and (iii) Hydraulic efficiency. 8 A Kaplan turbine working under a head of 20 m develops BHP. The outer diameter of the runner is 3.5 m and the hub diameter is 1.75 m. the guide blade angle at the extreme edge of the runner is 30 degree. The hydraulic and overall efiiciency of the turbine are 88% and 84 % respectively. If the velocity of whirl is zero at outlet. Evaluate the i. Runner vane angles at inlet and outlet at the extreme edge of the runner and ii. Speed of the turbine BT-1-11 BT-2-7 BT-6-4 BT-2-8 BT-3-7 BT-1-12 BT-5-4

7 9 A Francis turbine is to be designed to develop 360 kw under a head of 70 m and a speed of 750 rpm. The ratio of width of runner to diameter of runner n is 0.1. The inner diameter of the runner is half the outer diameter. The flow ratio is The hydraulic efficiency is 95% and the mechanical efficiency is 84%. Four percent of the circumferential area of runner is to be occupied by the thickness of the vanes. The velocity of flow is constant and the discharge is radial at exit. Solve the following: i. The diameter of the wheel ii. The quantity of water supplied iii. The guide vane angle at inlet and iv. Runner vane angles at inlet and exit. 10 A Kaplan turbine is to be designed to develop 9000kW. The net available head is 5.6m. The speed ratio is 2.09 and the flow ratio is The overall efficiency is 86% and the diameter of the boss is one-third the diameter of the runner. Appraise the diameter of the runner, speed and specific speed of the turbine. BT-3-8 BT-4-4 UNIT V: PUMPS PART A 1 Classify pumps on the basis of transfer of mechanical energy. BT Differentiate pump and turbine. BT What is the role of a volute chamber of a centrifugal pump? BT List the types of impellers and casing for a centrifugal pump BT What is meant by priming of pumps? BT Criticize the manometric efficiency and mechanical efficiency of a centrifugal BT-4-14 pump? 7 What is net positive suction head in a centrifugal pump? BT The difference between the water levels in the sump and the overhead tank is BT-5-9 H. what is the total head to be generated by the pump for pumping the liquid? 9 Define specific speed of pump. BT Write the equation for specific speed for pump and turbines. BT What is meant by multistage pump? BT What are the types of characteristic curves? BT Define cavitation in pumps. BT Distinguish the positive displacement pump and roto dynamic pump? BT Mention the main components of reciprocating pump BT Define suction and delivery strokes. BT Write about negative slip. How does it occur? BT What is indicator diagram with sketch? BT Give detail about an air vessel? State its function BT What is the function of foot valve in a pump? BT-6-10 PART-B

8 1 Explain with a neat sketch, the construction details and working principles of a centrifugal pump. 2 The centrifugal pump has the following characteristics. Outer diameter of impeller is 800mm: width of the impeller vane at outlet = 100mm: angle of the impeller vanes at outlet is 40degree. The impeller runs at 550 rpm and delivers 0.89m3/sec under an effective head of 35m. A 500kW motor is used to drive the pump. Identify the manometric, mechanical and overall efficiencies of the pump. Assume water enters the impeller vanes radially at inlet. 3 Examine the vane angle at the inlet of a centrifugal pump impeller having 200mm diameter at the inlet and 400mm diameter at outlet. The impeller vanes are set back at angle of 45 degree to the outer rim and the entry of the pump is radial. The pump runs at 1,000rpm and the velocity of flow through the impeller is constant at 3m/s. also calculate the work done per kn of water and the velocity as well as direction of the water at outlet. 4 List the following (1) total head, (2) capacity and (3) overall efficiency of a single acting three throw pump with diameter of each cylinder = 28cm, stroke = 42 cm, speed = 120 rpm, suction head =2.5 m suction pipe diameter = 20 cm, suction pipe length = 5 m, delivery head = 12m, delivery pipe diameter = 15 cm, length of delivery pipe = 18 m, coefficient of friction =0.008, and shaft power = 65 kw. Air vessel is provided with both suction and delivery pipes. 5 A centrifugal pump having outer diameter equal to two times the inner diameter and running at 1000 rpm works against a total head of 40 m. The velocity of flow through the impeller is constant and equal to 2.5 m/s. The vanes are set back at an angle of 40 degrees at outlet. If the outer diameter of the impeller is 500 mm and width at outlet is 50 mm. List the following i. Vane angle at inlet ii. Work done by impeller on water per second iii. Manometric efficiency 6. i. Explain the working principle of double acting reciprocating pump with a neat sketch. (8) ii. A single acting reciprocating has a plunger diameter of 250mm and stroke length of 350 mm. the speed of the pump is 60 rpm and the discharge is 0.02 cumecs of water. List the following: 1. The theoretical discharge 2. Coefficient of discharge 3. Percentageslip (8) 7 The diameter and stroke length of a single acting reciprocating pump are 50mm and 100 mm respectively. It takes the supply of water from a sump 4 m below the pump through a pipe 6 m long and 30 mm in diameter. It delivers water to a tank 15 m above the pump through a pipe 40 mm in diameter and 20m long. If separation occur 70 kn/m 2 below the atmospheric pressure, Report the maximum speed at which pump may be operated without separation. Assume that the piston has a simple harmonic motion. 8 Examine is indicator diagram. Explain the indicator diagram of a reciprocating pump with a neat sketch i. Without air vessels on both suction and delivery sides. ii. With air vessels only on suction side. BT-3-9 BT-2-9 BT-4-5 BT-1-13 BT-1-14 BT-1-15 BT-2-10 BT-4-6

9 9 Evaluate the working principles of vane pump and gear pump with neat sketches BT Write and explain the working of rotary pump and draw the performance curve BT-6-5 VALLIAMMAI ENGINEERING COLLEGE DEPARTMENT OF CIVIL ENGINEERING CE6403: APPLIED HYDRAULIC ENGINEERING QUESTION BANK S.no UNIT NO. BT1 BT2 BT3 BT4 BT5 BT6 Total Question Part-A Unit-1 Part-B Part-A Unit-2 Part-B Part-A Unit-3 Part-B Part-A Unit-4 Part-B Part-A Unit-5 Part-B TOTAL NO. OF QUESTIONS IN EACH PART PART-A 100 PART-B 50 TOTAL 150

10