JNTU
JNTU B.Tech II FLUID MECHANICS Previous Question Paper (November/December - 2018 - R13)
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. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
State Newton’s law of viscosity and give examples of its application.
Answer
Newton's law of viscosity states that the shear stress on a fluid element is directly proportional to the rate of shear strain (velocity gradient). Mathematically, τ = μ(du/dy), where τ is shear stress, μ is dynamic viscosity, and du/dy is the velocity gradient. Examples include the flow of oil in a journal bearing and the movement of a plate over a thin fluid film.
List out the examples where capillarity effects play a prominent role.
Answer
Capillarity effects are prominent in the following: 1) Rise of sap in plants and trees, 2) Movement of moisture through soil pores, 3) Rise of oil in lamp wicks, and 4) The formation of the meniscus in a glass tube containing mercury or water.
List out different forces of fluid flow.
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Explain stream line and stream tube.
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Explain the principle of venturimeter with a neat sketch.
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Discuss the relative merits of venturimeter with respect to orifice-meter.
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Define turbulent boundary layer and boundary layer thickness.
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Derive an expression for the displacement thickness.
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How will you determine the loss of head due to friction in pipes by using Chezy’s Formula?
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What do you understand by minor energy losses in pipes?
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Part B
a) What do you understand by hydrostatic equation? With the help of this equation derive the expression for the total thrust on a submerged plane area. b) Find the total pressure and depth of centre of pressure on a triangular plate of base 3 m and height 3 m which is immersed in water in such a way that plane of a plate makes an angle of 60 degrees with the free surface. The base of the plate is parallel to water surface and at the depth of 2 m from water surface.
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a) Distinguish between manometers and mechanical gauges. What are the different types of mechanical pressure gauges? b) A U-tube manometer connects two pressure pipes A and B. Pipe A contains carbon tetrachloride having specific gravity 1.594 under a pressure of 11.772 N/cm^2 and pipe B contains oil of sp. gr. 0.8 under a pressure of 11.772 N/cm^2. The pipe A lies 2.5 m above pipe B. Find the difference of pressure measured by mercury as fluid filling U-tube.
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The velocity vector in a fluid flow vector is given by V = 3x^2 i - 2x yj + 5 rk. Find the velocity and acceleration of a fluid particle at (1, 2, 3) at time, t=1.
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Define two-dimensional stream function and velocity potential. Show the following stream function: psi = -6x + 4y + 7xy Represents an irrotaional flow. Find its velocity potential.
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In a 200 mm diameter horizontal pipe, a venturimeter of 0.5 contraction ratio has been fixed. The head of water on venturimeter when there is no flow is 4 m (gauge). Find the rate of flow for which the throat pressure will be 4 m of water absolute. Take Cd = 0.97 and atmosphere pressure head = 10.3 m of water.
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A 300 mm diameter pipe carries water under a head of 20 m with a velocity of 3.5 m/s. If the axis of the pipe turns through 45 degrees, find the magnitude and direction of the resultant force at the bend.
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Find the displacement thickness, momentum thickness and energy thickness for velocity distribution in the boundary layer given by u/U = (y/delta) - (y/delta)^2. Where u = Velocity in the boundary layer at the distance y, U = Free-stream velocity, delta = Boundary layer thickness.
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A kite 0.8 m x 0.8 m weighing 0.4 kgf (3.924 N) assumes an angle of 12 degrees to the horizontal. The string attached to the kite makes an angle of 45 degrees to the horizontal. The pull on the string is 2.5 kgf (24.525 N) when the wind is flowing at a speed of 30 km/hour. Find the corresponding co-efficient of drag and lift. Density of air is given as 1.25 kg/m^3.
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Explain pipes in series and parallel with neat sketches.
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Water is flowing vertically downwards through a 10 cm diameter pipe at the rate of 50 l.p.s. At a particular location, the pipe suddenly enlarges to 20 cm diameter. A point P is located 50 cm above the section of enlargement and another point Q is located 50 cm below it in the enlarged portion. A pressure gauge connected at P gives a reading of 19.62 N/cm^2. Calculate the pressure at location Q neglecting friction loss between P and Q but considering the loss due to sudden enlargement. What will be the pressure at Q if the same discharge flow upwards assuming that the pressure p remains the same? Consider the loss due to contraction with Cc = 0.60 but neglect friction loss between P and Q.
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