Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Summer 4th Sem 3141906 Fluid Mechanics And Hydraulics Machines Previous Question Paper

Seat No.: ________

Enrolment No.___________

**GUJARAT TECHNOLOGICAL UNIVERSITY**

**BE - SEMESTER? IV EXAMINATION ? SUMMER 2020**

**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**

**Instructions:**

**1. Attempt all questions.**

**2. Make suitable assumptions wherever necessary.**

**3. 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

**07**

will you obtain Bernoulli's equation from Euler's equation?

**Q.2 (a)**How repeating variables selected for dimensionless analysis?

**03**

**(b)**With neat sketch explain the conditions of equilibrium for floating

**04**

body.

**(c)**Define uniform flow. Obtain stream and velocity potential function

**07**

when flow is parallel to x-axis. Also plot uniform flow (parallel to x

axis).

**OR**

**(c)**Derive from first principles, the conditions for ir-rotational flow.

**07**

Prove that for potential flow, both the stream function and velocity

potential function satisfy the Laplace equation.

**Q.3 (a)**Differentiate between stream and streak line.

**03**

**(b)**Define centre of pressure. Obtain expression for centre of pressure

**04**

for vertical plane surface submerged in liquid.

**(c)**The water is flowing through a taper pipe of length 100 m having

**07**

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.

**OR**

**Q.3 (a)**The strea

**03**

m function for two dimensional flow is given by = 2xy.

Find velocity potential function .

**(b)**Define and explain the terms: HGL, TEL

**04**

**(c)**State Buckingham's ? theorem. The efficiency of a fan depends

**07**

on density , dynamic viscosity of the fluid, angular velocity ,

diameter D of the rotor and discharge Q. Express in terms of

dimensionless parameters.

**Q.4 (a)**Derive the expression of force in x and y direction when jet striking

**03**

symmetrical curved vane tangentially at one tip and leaving other

end.

**(b)**Prove that maximum velocity in a circular pipe for viscous flow is

**04**

equal to two times the average velocity of flow.

**(c)**Derive Darcy ? Weisbach equation.

**07**

1

**OR**

**Q.4 (a)**Define priming. Why priming is necessary in centrifugal pump?

**03**

**(b)**Classify hydraulic turbines with examples based on following

**04**

criteria:

i. Energy at inlet

ii. Direction of flow through runner

iii. Head at the inlet of turbine

iv. Specific speed of turbine

**(c)**A Pelton wheel is to be designed for the following specifications:

**07**

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

ii. The number of jets required

iii. Diameter of the jet.

iv.

**Q.5 (a)**Explain the advantages of Kaplan turbine over Fransis turbine.

**03**

**(b)**Define cavitation. State necessary precautions against cavitation in

**04**

pump.

**(c)**Why governing of turbine is required? Explain governing of Pelton

**07**

wheel with neat sketch.

**OR**

**Q.5 (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

**07**

centrifugal pump.

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This post was last modified on 04 March 2021