JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II FLUID MECHANICS AND OPEN CHANNEL HYDRAULICS Previous Question Paper (November/December - 2018 - R13)
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.
Part A
Distinguish between ideal fluids and real fluids. Explain the importance of compressibility in fluid flow.
Answer
An ideal fluid is incompressible and has zero viscosity, whereas a real fluid possesses viscosity and is compressible. Compressibility is significant in fluid flow when the flow velocity is high (approaching the speed of sound), as it leads to significant changes in fluid density and pressure, which must be accounted for in aerodynamic and high-speed gas dynamics calculations.
The velocity distribution for flow over a flat plate is given by
Answer
Given: u = (3/2)y - (3/2)y^2, μ = 8 Poise = 0.8 Ns/m^2, y = 0.09 m. The velocity gradient (du/dy) is:
At y = 0.09 m:
Shear stress (τ) = μ(du/dy):
What do you mean by separation of boundary layer?
Answer
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How will you determine whether a boundary layer flow is attached flow, detached flow or on the verge of separation?
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Define an orifice and a mouthpiece. What is the difference between the two?
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The head of water over the centre of an orifice of diameter 30 mm is 1.5 m. The actual discharge through the orifice is 2.35 litres/sec. Find the co-efficient of discharge.
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Show that ratio of inertia force to viscous force gives the Reynold’s number.
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Define and explain Froude’s number and Mach number.
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Differentiate between: Steady and unsteady flow and Laminar and turbulent flow.
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Explain rapidly varied flow and gradually varied flow.
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Part B
Find an expression for the force exerted and centre of pressure for a completely submerged inclined plane surface. Can the same method be applied for finding the resultant force on a curved surface immersed in the liquid? If not, why?
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What do you understand by terms: i) Total acceleration, ii) Convective acceleration, and iii) Local acceleration?
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A 40 cm diameter pipe, conveying water, branches into two pipes of diameters 30 cm and 20 cm respectively. If the average velocity in the 40 cm diameter pipe is 3 m/s, find the discharge in this pipe. Also, determine the velocity in 20 cm pipe if the average velocity in 30 cm diameter pipe is 2 m/s.
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A venturimeter with a throat diameter of 7.5 cm is installed in a 15 cm diameter pipe. The pressure at the entrance to the metre is 70 kPa (gauge) and it is desired that the pressure at any point should not fall below 2.5 m of absolute water. Determine the maximum flow rate of water through the meter. Take Cd = 0.97 and atmospheric pressure as 100 kPa.
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State Bernoulli’s theorem for steady flow of an incompressible fluid. Derive an expression for Bernoulli’s theorem from first principle and state the assumption made for such a derivation.
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Prove that the error in discharge due to the error in the measurement of head over a rectangular notch is given by
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A convergent-divergent mouthpiece having throat diameter of 60 mm is discharging water under a constant head of 3.0 m. Determine the maximum outlet diameter for maximum discharge. Find maximum discharge also. Take the atmospheric pressure head = 10.3 m of water and separation head = 2.5 m of water absolute.
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Define and explain hydraulic gradient line and total energy line.
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What do you mean by equivalent pipe? Obtain expression for equivalent pipe?
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Explain Buckingham’s pi theorem in detail by taking an example of fluid flow problem.
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Derive the condition for the best side slope of the most economical trapezoidal channel.
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Find the side slope in a trapezoidal section of maximum efficiency which will carry the same flow as a half square section of the same area.
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Prove that the loss of energy head in hydraulic jump is equal to
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Obtain the relationship between the Froude Numbers of flow before and after the hydraulic jump in a horizontal rectangular channel.
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