Rajasthan Technical University 2010 B.Tech Mechanical Engineering Fluid Mechanics (mechanical Engg.) - Question Paper
RTU Fluid Mechanics (mechanical Engg.)
Rajasthan tech. University
B.tech four sem (Main/back)
Year July 2010
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[Min. Passing Marks: 24 | |||||||||||||||||||
Attempt any five questions, selecting one question from each unit. All questions carry equal marks. (Schematic diagrams must be shown wherever necessary. Any data you feel missing suitably be assumed and stated clearly. Units of quantities used / calculated
must be stated clearly.)
Use of following supporting material is permitted during examination. (Mentioned in form No. 205)
1.__Nil__2. Nil_
UNIT-I
1 (a) What do you mean by :
(i) Surface Tension
(ii) Dynamic viscosity
(iii) Weight Density
(iv) Newtonian Fluid
(v) Cavitation
(vi) Bulk Modulus of Elasticity.
(b) In measuring the unit energy of a mineral oil (specific gravity = 0.85) by the bubble method, a tube having an internal diameter of 1.5 mm is immersed to depth of 12.5 mm in oil. Air is forced through the tube forming a bubble at the lower end. What magnitude of the unit surface energy will be indicated by a maximum bubble pressure intensity of 150 N/m2.
2 (a) Derive expression for the depth of centre of pressure from
free surface of liquid of an inclined plane surface submerged in the liquid.
(b) Explain briefly the following types of equilibrium of floating bodies :
(i) Stable equilibrium
(ii) Unstable equilibrium
(iii) Natural equilibrium.
10
Explain the following :
3 (a) (b)
4 (a)
(i) Laminar and Turbulent flow
(ii) Stream line and Streak line
(iii) Circulation and Vortidty
(iv) Uniform and Nonuniform flow
(v) Steady and Unsteady flow.
State and prove Bernoulli's Equation. Mention clearly all the assumptions made while deriving Bernoulli's Equation. What are the limitations of the Bernoulli's Equation ?
The flow field of a fluid is given by v = xyi+2yzj -[yz + z2k
(i) Show that it represents a possible three-dimensional steady incompressible continuous flow ?
(ii) Is this flow rotational or irrotational ? If rotational,
determine at point A(2,4,6)
(i) Angular velocity
(ii) Vorticity
(iii) Shear strain
(iv) Linear strain.
Derive Momentum Equation and mention its application to moving blades.
6
5 (a) Derive an expression for the loss of head due to sudden contraction.
(b) A 2500 m long pipe line is used for the transmission of power 120 kW power, is to be transmitted through the pipe in which water having a pressure of 4000 kN/m2 at inlet is flowing. If the pressure drop over the length of . pipe is 800 kN/m2 and / = 0.006, find : (i) Diameter of the pipe and
(ii) Efficiency of transmission.
4E2051] |a|l||||||lBH| 2 [Contd..
How are notches and weirs classified ? Find an expression for the discharge over a triangular notch.
6 (a) (b)
7 (a) (b)
8 (a) (b)
Show that the velocity distribution for turbulent flow through rough pipes is given as
JL-5.75.o*0g)+.5
where uf~ shear velocity, y = distance from pipe wall k = roughness factor.
8
Derive expression for velocity distribution for correlate flow and draw the velocity distribution as a function of dimensionless pressure gradient.
A pipe 60 mm diameter and 450 m long slopes upwards at lm so. An oil of viscosity 0.9 NS/m2 and specific gravity
0.9 is required to be pumped at the rate of 5 lit/sec.
(i) Is the flow laminar ?
(ii) What pressure difference is required to attain this condition ?
(iii) What is the power of the pump required assuming an overall efficiency of 65% ?
(iv) What is the centre-line velocity and velocity gradient at pipe wall ?
What is the physical significance of Reynold number. Mach number, Froude number and Weber number.
Show that the power P developed in a water turbine can be
D pD2N ND V JgN
expressed as P = PN3D5 <|>
where p= mass density of liquid, N = speed in r.p.m.
D = diameter of the runner, B = width of the runner p. = Coefficient of dynamic viscosity.
Under what conditions it can be used to determine the characteristics of a similar machine ?
10
4E2051]
UNIT-V
9 (a) Explain the different types of hydraulic similarities that must exist between prototype and its model.
(b) Find Boundary Layer thickness, shear stress, local coeff. of drag and coeff. of drag when velocity distribution is laminar boundary layer is given by
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1 |
V |
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UJ |
10
10 Write short notes on :
(i) Flow past cylinder
(ii) Various types of drag
(iii) Boundary layer control.
16
4E2051] I lllll IIIIJ III II Mil lll'llll III 4 [ 5000 ]
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| Earning: Approval pending. |
