Question

10. The figure shows a horizontal pipeline with0.3 m sudden enlargement. The energy grade line andEnergr grade ine the hydraalic grade line under a cerlain flow of an incompressible fluid of specific weight 10m kN/m are also shown. The pressure change due to the enlargement is most nearly a) a decrease of 27 kPa b) an increase of 27 kPs c) a decrease of 30 kPa d) an increase of 30 kPa tydradic grade ine 11. If the density of the air is 1.2 kgm find F, in newions a) 24 b) 3.6 e) 4.8 d) 7.6 12. A laminar flow exists in a pipe flow. We know that a) the velocity profile is linear b) the Reynolds number is less than 2000. c) the shear stress distribution is linear. d) the pipe is smooth 13. The head loss in a pipe can be cakulated using a) the Bemculli equation. b) the Darcy-Weisbach equstion. c) the Chezy Manning equation. d) the Momentum equation

Answer 1

Answer 10) velocity head before enlargement = 5 m

Velocity head after enlargement = 2m

Decrease in velocity head is shown as 0.3 m thus increase in pressure head = 5-2-0.3 = 2.7 m

Thus ∆P/Y = 2.7 thus ∆P = 2.7*10 KN/m2 = 27 KN/m2

Thus there is an increase of pressure by 27 KN/m2 . Thus option B is correct answer.

Answer 11) image is not clearly visible. However considering velocity = V m/s and dia = D m . Density of air = 1.2 kg/m3. Force F = change in momentum = ¶QV = 1.2*π * D^2/4 * V^2

Substituting D = 0.02 m and V = 80 m/s we get F = 2.4127 N

Thus option A would be correct answer.

Answer 12) For laminar flow in pipes, Reynolds number < 2000. Thus option B is correct answer.

Answer 13) Head loss due to friction in pipe can be calculated using Darcy weisbach equation. Thus option B is correct answer.