Mechanics of Fluids

The pressure diagrams show that for the next step (B changed
from 0.08 to 0.06) the 13.61 m wave returns and the corresponding
pressure rise at the valve changes sign. The table then
continues:
B (m 1/2 · s −1 ) Head at valve, h (m) u (m · s −1 ) �h (m)
0.06 100 − 11.82 − 13.61 + 15.73
+ 18.18 + 21.01
+ 30.41 + 32.15
= 192.05
0.04 100 − 11.82 − 13.61 − 15.73
+ 18.18 + 21.01 + 30.41
+ 32.15 + 33.53
= 194.12
0.02 100 − 11.82 − 13.61 − 15.73
− 18.18 + 21.01
+ 30.41 + 32.15
+ 33.53 + 34.26
= 192.02
0 100 − 11.82 − 13.61 − 15.73
− 18.18 − 21.01 + 30.41
+ 32.15 + 33.53
+ 34.26 + 33.90
= 183.90
0.831 32.15
0.557 33.53
0.277 34.26
0 33.90
Although the valve is now closed the waves continue their movement,
and the pressure increments at the valve change sign according to
Fig.12.8. However, as the velocity at the valve is zero and must remain
zero, no new waves can be generated.
B (m 1/2 · s −1 ) Head at valve, h (m) u (m · s −1 ) �h (m)
0 100+11.82−13.61−15.73
− 18.18 − 21.01 − 30.41
+ 32.15 + 33.53
+ 34.26 + 33.90
= 146.72
0 100+11.82+13.61−15.73
− 18.18 − 21.01 − 30.41
− 32.15 + 33.53
+ 34.26 + 33.90
= 109.64
0 100+11.82+13.61+15.73
− 18.18 − 21.01 − 30.41
− 32.15 − 33.53
+ 34.26 + 33.90
= 74.04
0 —
0 —
0 —
0 ...= 41.88 0 —
0 ...= 16.10 0 —
0 ...= 53.28 0 —
Pressure transients 573