Valve Stroking in Separated Pipe Flow

Apart from assessing the magnitude of a pressure surge propagated within a pipe flow system, the engineer needs to be able to reduce the surge, possibly using a process known as valve stroking. Although methods of valve stroking exist, these are not applicable to systems in which flow separation occurs due to the loss of control by the valve on the separated column. The writer develops two methods for dealing with such a situation and shows that for the first method a surge reduction of 40% is typical. These results are supported by experimental evidence. The second method indicates that a 95% reduction in the surge is possible although at present no experimental data are available to confirm this.