GTU BE 2020 Summer Question Papers || Gujarat Technological University
Subject Code: 3141906 Date:27/10/2020
Subject Name: Fluid Mechanics and Hydraulics Machines
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Seat No.: Enrolment No.
GUJARAT TECHNOLOGICAL UNIVERSITY
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BE - SEMESTER- IV EXAMINATION — SUMMER 2020Subject Code: 3141906 Date:27/10/2020
Subject Name: Fluid Mechanics and Hydraulics Machines
Time: 10:30 AM TO 01:00 PM Total Marks: 70
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Instructions:
- Attempt all questions.
- Make suitable assumptions wherever necessary.
- Figures to the right indicate full marks.
| Marks | |
| Q.1 | |
| (a) Explain hypothesis of continuum. | 03 |
| (b) State and prove Pascal’s law. | 04 |
| (c) Derive Euler’s equation of motion. State assumptions made. How will you obtain Bernoulli’s equation from Euler’s equation? | 07 |
| Q.2 | |
| (a) How repeating variables selected for dimensionless analysis? | 03 |
| (b) With neat sketch explain the conditions of equilibrium for floating body. | 04 |
| (c) Define uniform flow. Obtain stream and velocity potential function when flow is parallel to x-axis. Also plot uniform flow (parallel to x axis). | 07 |
| OR | |
| (c) Derive from first principles, the conditions for ir-rotational flow. Prove that for potential flow, both the stream function and velocity potential function satisfy the Laplace equation. | 07 |
| Q.3 | |
| (a) Differentiate between stream and streak line. | 03 |
| (b) Define centre of pressure. Obtain expression for centre of pressure for vertical plane surface submerged in liquid. | 04 |
| (c) The water is flowing through a taper pipe of length 100 m having diameters 600 mm at the upper end and 300 mm at the lower end, at the rate of 50 lps. The pipe has slope of 1 in 30. Find the pressure at the lower end if pressure at the higher level is 19.62 N/cm². | 07 |
| OR | |
| Q.3 | |
| (a) The stream function for two dimensional flow is given by ? = 2xy. Find velocity potential function F. | 03 |
| (b) Define and explain the terms: HGL, TEL | 04 |
| (c) State Buckingham’s p — theorem. The efficiency ? of a fan depends on density ?, dynamic viscosity µ of the fluid, angular velocity ?, diameter D of the rotor and discharge Q. Express ? in terms of dimensionless parameters. | 07 |
| Q.4 | |
| (a) Derive the expression of force in x and y direction when jet striking symmetrical curved vane tangentially at one tip and leaving other end. | 03 |
| (b) Prove that maximum velocity in a circular pipe for viscous flow is equal to two times the average velocity of flow. | 04 |
| (c) Derive Darcy — Weisbach equation. | 07 |
| OR | |
| Q.4 | |
| (a) Define priming. Why priming is necessary in centrifugal pump? | 03 |
| (b) Classify hydraulic turbines with examples based on following criteria: --- Content provided by FirstRanker.com --- i. Energy at inletii. Direction of flow through runner iii. Head at the inlet of turbine iv. Specific speed of turbine | 04 |
| (c) A Pelton wheel is to be designed for the following specifications: Shaft power = 11.772 kW, Head = 380 m, Speed = 750 rpm, Overall efficiency = 86%, Jet diameter is not to exceed one-sixth of the wheel diameter. Determine: i. The wheel diameter --- Content provided by FirstRanker.com --- ii. The number of jets requirediii. Diameter of the jet. | 07 |
| Q.5 | |
| (a) Explain the advantages of Kaplan turbine over Francis turbine. | 03 |
| (b) Define cavitation. State necessary precautions against cavitation in pump. | 04 |
| (c) Why governing of turbine is required? Explain governing of Pelton wheel with neat sketch. | 07 |
| OR | |
| (a) Describe working of hydraulic accumulator with neat sketch. | 03 |
| (b) Write short note on NPSH. | 04 |
| (c) Explain briefly different losses and efficiencies associated with centrifugal pump. | 07 |
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