Q.8 A vertical pipeline carrying water changes in diameter from 200mm at a position to 500mm at another position which is 3m at a higher level. If the pressure at ‘A’ ‘B’ and are 80kN/m2 and 60kN/m2 respectively and discharge is 200 litres/sec, ‘A’ ‘B’ determine the loss of head and direction of flow (Dec2013, July 2014 ) Ans: Given Q = 200 lit/sec = 0.2m3/s, DA = 200mm = 0.2m, DB = 500mm = 0.5m (ZB ZA)= 3m, pA = 80kN/m2, pB = 60kN/m2, – The velocity at and can be ‘A’ ‘B’ obtained by continuity equation Q  VA 6.366 /  m s  0.2     4  AA 0.22    4   Q  VB 0.2  AB    0.52  1.018 /  m s Energy head at ‘A’ 2  p A A  EA Z 2  A  g w 80  0   EA 9.81 10.21m  2  g Total Energy head at ‘B’ 2 pB B  EB ZB 2  g  w 60  3   EB 9.81  9.169m 2  g Since EA> EB, The direction of flow will be from to i.e. Upward  “A” “B” The loss of head = (EA EB) = (10.21-9.169) = 1.041m –
Q.8 A vertical pipeline carrying water changes in diameter from 200mm at a position ‘A’ to 500mm at another position ‘B’ which is 3m at a higher level. If the pressure at ‘A’ and ‘B’ are 80kN/m2 and 60kN/m2 respectively and discharge is 200 litres/sec, determine the loss of head and direction of flow (Dec2013, July 2014 ) Ans: Given Q = 200 lit/sec = 0.2m3/s, DA = 200mm = 0.2m, DB = 500mm = 0.5m (ZB – ZA)= 3m, pA = 80kN/m2, pB = 60kN/m2, The velocity at ‘A’ and ‘B’ can be obtained by continuity equation Q VA   0.2    6.366 m / s  AA Q VB  AB   0.22   4   0.2    0.52   4   1.018 m / s Energy head at ‘A’ EA  Z A p A   w 2 A 2  g EA  0  80  9.81 2  g  10.21m Total Energy head at ‘B’ EB  ZB pB  w 2 B 2  g EB  3  60  9.81 2  g  9.169m Since EA> EB, The direction of flow will be from “A” to “B” i.e. Upward  The loss of head = (EA – EB) = (10.21-9.169) = 1.041m
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