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)