JNTU
JNTU B.Tech II MECHANICS OF FLUIDS Previous Question Paper (December - 2018 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
Explain Archimede’s principle.
Answer
Archimedes' principle states that a body immersed in a fluid is buoyed up by a force equal to the weight of the fluid displaced by the body. This upward force, known as the buoyant force, acts vertically upward through the center of gravity of the displaced fluid.
Where Fb is the buoyant force, ρ is the density of the fluid, g is the acceleration due to gravity, and V is the volume of the fluid displaced.
List out different fluid properties along with their units.
Answer
The fundamental properties of fluids and their respective SI units are as follows:
- Mass Density (ρ): Mass per unit volume, measured in kg/m3.
- Specific Weight (w or γ): Weight per unit volume, measured in N/m3.
- Specific Gravity (S): A dimensionless ratio of the density of a fluid to the density of a standard fluid (water).
- Dynamic Viscosity (μ): The measure of a fluid's resistance to gradual deformation by shear stress, measured in N·s/m2 or Pa·s.
- Kinematic Viscosity (ν): The ratio of dynamic viscosity to density, measured in m2/s.
- Surface Tension (σ): The tensile force per unit length on a fluid surface, measured in N/m.
Differentiate fluid statics and kinematics.
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Explain what is vorticity.
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Distinguish between surface and body forces.
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Explain Froude number along with its significance.
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What are the practical applications of boundary layer theory?
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Differentiate drag and lift.
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Differentiate pressure head and piezometric head.
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List out major and minor losses along with expressions for it.
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Part B
What is the difference between dynamic viscosity and kinematic viscosity. State their units of measurements.
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Two plates are placed at a distance of 0.15 mm apart. The lower plate is fixed while the upper plate having surface area 1.0 m2 is pulled at 0.3 m/s. Find the force and power required to maintain this speed, if the fluid separating them is having viscosity of 1.5 poise.
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State and explain Newton’s law of viscosity with a neat sketch and give examples of its application.
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In a stream of glycerine in motion, at a certain point the velocity gradient is 0.25 metre per sec per metre. The mass density of fluid is 1268.4 kg per cubic metre and kinematic viscosity is 6.30 x 10^-4 square metre per second. Calculate the shear stress at the point.
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Define the following and give one practical example for each: (i) Laminar flow (ii) Turbulent flow (iii) Steady flow and (iv) Uniform flow.
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The water is flowing through a pipe having diameters 20 cm and 15 cm at sections 1 and 2 respectively. The rate of flow through pipe is 40 litres/s. The section 1 is 6 m above datum line and section 2 is 3 m above the datum. If the pressure at section 1 is 29.43 N/cm2, find the intensity of pressure at section 2.
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State and explain the equation of continuity. Obtain an express for continuity equation for a one dimensional flow.
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Water is flowing through a pipe having diameters 30 cm and 15 cm at the bottom and upper end respectively. The intensity of pressure at the bottom end is 29.43 N/cm2 and the pressure at the upper end is 14.715 N/cm2. Determine the difference in datum head if the rate of flow through pipe is 50 lit/s.
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The thrust T of a propeller depends on its diameter D, the fluid density rho, dynamic viscosity mu, the revolutions per unit time N, and the velocity of advance V with respect to the undisturbed fluid. By means of dimensional analysis, show that the appropriate non-dimensional parameters are T/(rho D^2 V^2) = f(mu/(rho V D), ND/V).
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A fluid flow phenomenon is to be studied in a model which is to be constructed by using Reynolds model law. Find the expressions for model to prototype ratios of velocity, discharge, pressure, work and power.
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What do you mean by boundary layer separation. What is the effect of pressure gradient on boundary layer separation?
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How will you find drag on a flat plate due to laminar and turbulent boundary layers?
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What are the boundary conditions that must be satisfied by a given velocity profile in laminar boundary layer flows? Explain.
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Explain pressure drag and skin friction drag.
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Obtain an expression for head loss in a sudden expansion in the pipe. List all the assumptions made in the derivation.
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A liquid of specific gravity 0.8 is flowing upwards at the rate of 0.08 m3/s, through a vertical venturimeter with an inlet diameter of 200 mm and throat diameter of 100 mm. The Cd = 0.98 and the vertical distance between pressure tappings is 300 mm. Find: (i) The difference in readings of the two pressure gauges, and (ii) The difference in the level of the mercury columns of the differential manometer.
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Define and explain the terms : (i) Hydraulic gradient line and (ii) Total energy line.
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An oil of Kinematic Viscosity 0.5 stoke is flowing through a pipe of diameter 300 mm at the rate of 320 litres per sec. Find the head lost due to friction for a length of 60 m of the pipe.
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