R5210106 Fluid Mechanics

R5

Code No: R5210106

II B.Tech I Semester(R05) Supplementary Examinations, December 2009 FLUID MECHANICS (Civil Engineering) Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Explain the phenomena surface Tension and capillarity.

[4+4]

(b) Two coaxial cylinders 12cm and 11.80cm in diameter and 3.5cm high have both their ends open and have a viscous liquid filled in between. A torque of 1.3N.m is produced on the inner cylinder when the outer one rotates at 80RPM. Determine the coefficient of viscosity of the liquid. [8] 2. (a) Find the total pressure force and the depth of centre of pressure on an inclined plane surface submerged in a liquid. (b) A trapezoidal plate of top width 6m, bottom width 5m and height 3.5m is immersed vertically in water with its parallel sides parallel to the water level and its top edge is at a depth of 2.5m below the water level. Find the water thrust an one side of the plate and depth of centre of pressure. [8+8] 3. (a) Identify the common features and differences between stream and velocity potential factions (b) Examine whether the velocity field, U = 2ax(3y 2 − x2 ) and V = 2ay (3x2 − y 2 ) represents a possible two dimensional incompressible fluid flow. [8+8] 4. (a) Explain how the impulse momentum equation is used to determine the resultant force exerted by a flowing fluid on a pipe bend. (b) Water is flowing through a taper pipe of length 50 m having diameters 40 cm at the upper end 20cm at the lower end at the rate of 60 lit/see. The pipe has a slope of 1 in 40. Find the pressure at the lower end if the pressure at the higher level is 24.525N/cm2 . [8+8] 5. (a) Explain how laminar and turbulent boundary layers are formed and distinguish between their characteristics. (b) A thin flat plate measuring 75 cm × 25 cm is exposed parallel to a stream of water of uniform velocity 1.2 m/sec. The flow takes place parallel to 25 cm side of the plate. If the kinematic viscosity of water is 1.1 centistokes, determine the maximum boundary layer thickness, shearing stress at the trailing edge and the drag an both sides of the plate. [8+8] 6. (a) Derive the expressions for discharge per unit width and shear stress for flow of viscous fluid between two parallel plates when one plate is moving and other at rest. (b) Two parallel plates kept 75 mm apart have laminar flow of glycerin between them with a maximum velocity of 1 m/sec. Calculate the difference in pressure between two points 25 m apart and the velocity gradients at the plates and velocity at 15 mm from the plate. Take viscosity of glycerine as 8.35 poise. [8+8] 7. (a) Drive an expression for head loss due to sudden enlargement of a pipe. (b) An oil of specific gravity 0.85 and viscosity 5CP flows through a pipe of diameter 400 mm at the rate of 50 lit/sec. Find the head lost in friction in this pipe of length 1000 km. Assume that f = 0.079/RN where RN is Reynolds Number. [8+8] 8. (a) Describe the principle and working of orifice meter with the help of a neat sketch. (b) In a calibration test of an orifice meter of with orifice diameter 4 cm is inserted in a pipe of 10 cm diameter. The mercury differential U-gauge connected to the meter gives a reading of 38 cm when 7.5 lit/sec of water flows through the meter. Compute the coefficient of discharge. [8+8] ?????