Abstract
The computerized method of characteristics was used to analyse, for a single pipeline discharging into the atmosphere, the effects of valve-closure schedule and pipe length on optimum water-hammer strength. It was found that the criteria of optimum water-hammer utilization are a non-linear inherent valve schedule in which the bulk of the pressure surge occurs near the beginning or towards the end of valve closure, together with as small a value of dimensionless valve-closure time and as high a value of wide-open valve area as is consistent with cavitation-free operation. Also, a comparison of the results with hydraulic ram test data suggests that optimum drive pipe length may be based solely on optimum water-hammer strength, in the light of the relative effects of pipe friction and dimensionless valve-closure time. In general, optimum pipe length is not highly sensitive to inherent valve-closure schedule, water-hammer strength, pipe size or reservoir head.
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