## Applied Fluid Mechanics - May 2015

### Civil Engineering (Semester 6)

TOTAL MARKS:

TOTAL TIME: HOURS

**1 (a)** Obtain the Hagen-Poiseuille equation for viscous flow through a circular pipe.(7 marks)
**1 (b)** Explain boundary layer growth over a flat plate. Also explain causes of flow
separation from a solid boundary.(7 marks)
**2 (a)** Calculate (i) the discharge per meter width (ii) pressure difference between two
points 5 m apart and (iii) velocity gradient and (iv) velocity at 2 mm from plate
for oil of viscosity 18 poise flowing between two parallel plates kept 10mm
apart, consider that the maximum velocity at the centre of plate = 1.8 m/s.(7 marks)
**2 (b)** Draw the specific energy curve for constant discharge in an open channel.
Explain the terms critical flow, sub critical and supercritical flow in terms of
Froude number.(7 marks)
**2 (c)** Calculate the displacement thickness, momentum thickness and energy thickness for the velocity distribution [dfrac{u}{V}=dfrac{y}{delta}] for a flat plate boundary.(7 marks)
**3 (a)** Explain the drag and lift force component on a submerged object. What do you
understand by Magnus effect?(7 marks)
**3 (b)** Water flows in a rectangular channel having Manning roughness coefficient n =
0.017. The channel slope is 1 in 7000. If the bottom width is 5 m and depth of
flow is 1.1 m, calculate the discharge in the channel. Also calculate the specific
energy and critical depth.(7 marks)
**3 (c)** What is a hydraulic jump? Discuss the various types of jump based on Froude
Number.(7 marks)
**3 (d)** Draw a neat sketch showing the elements of a hydroelectric plant. Discuss the
components of Pelton turbine in detail.(7 marks)
**4 (a)** A Pelton turbine develops 2500kW under a head of 200 m. Considering a speed
ratio of 0.43, coefficient of velocity = 0.97 and specific speed of 17, calculate
(i) the diameter of Pelton wheel and (ii) jet diameter. Take overall efficiency =
85%.(7 marks)
**4 (b)** What is the function of a draft tube? Also sketch the different type of draft
tubes.(7 marks)
**4 (c)** What is a backwater curve? Calculate the length of backwater curve considering that the depth increases from 3 m to 5 m in a river having width of 85m. The roughness coefficient may be taken as 0.035 and channel bottom slope of 1 in 3000.(7 marks)
**4 (d)** Discuss the terms specific speed, unit speed, unit discharge and unit power for a
Turbine.(7 marks)
**5 (a)** What are the general requirements of a ventilation system? Differentiate between natural and mechanical ventilation system.(7 marks)
**5 (b)** Explain the Buckingham's π- theorem in dimensional analysis.(7 marks)
**5 (c)** Explain the terms geometric similarity, kinematic similarity and dynamic
similarity for physical models.(7 marks)
**5 (d)** What do you understand by cavitation of a hydraulic machine? How can we
prevent cavitation of hydraulic machines?(7 marks)