A Numerical Exploration of Transient Decay Mechanisms in Water Distribution Systems - Advances in Control and Automation of Water Systems - page 21

• positive water hammer in pipeline with single change of diameter: contraction
and extension.
• positive water hammer in pipeline with local leak in two scenarios: with the
outflow from the leak to the overpressure reservoir and with free outflow from
the leak (to atmospheric pressure, with the possibility of sucking in air in nega-
tive phase). This was the reason for the sucking air in negative phase for Rasht
city water-pipeline.
figure 1.9 Column separations due to pump turned off--Rasht city Water Pipeline
Transmission Line: (a) with surge tank--pipeline in leakage condition--pipeline was sucked air
in negative phase, (b) without surge tank--pipeline in no leakage condition.