Unappreciated challenges in applying four quadrant pump data to waterhammer simulation

Trey Walters, P.E., Scott Lang and David Miller, P.E., Applied Flow Technology - 13^th International Conference on Pressure Surges 2018, Bordeaux, France, November 14-16, 2018

Part 1: Fundamentals
The transient analysis of reverse flow and rotation in pumps has evolved over the years into modern four quadrant pump waterhammer simulation. Exact characteristics for a given pump for reverse flow and/or reverse rotation are normally unavailable, and manufacturer curves are often mapped to previously published four quadrant data sets for similar pumps. Assumptions made in this mapping process can cause extreme differences in the simulation. If these assumptions are unaddressed, critically incorrect conclusions about the system’s transient behavior may be made, impacting both design and operation. 
The available choices to the waterhammer analyst and the consequences of those choices are thoroughly detailed in Part 1 of this paper.

Part 2: Application Examples
Transient analysis of reverse flow and rotation in pumps requires the use of four quadrant data. This data is normally unavailable for a given pump, and existing dimensionless four quadrant data is selected based on specific speed. There are different methods for dimensionalizing the four quadrant data, which can result in significant differences in transient predictions. This study examines four examples with three exhibiting reverse flow. The two most convenient methods of dimensionalizing four quadrant data are used, and significant differences in transient predictions are demonstrated and discussed.

© BHR Group 2018 Pressure Surges 13