The possibility of reverse pump flow or rotation during a waterhammer simulation requires the use of methods for estimating four quadrant pump characteristics. For the last five decades the state-of-the-art has been the Suter Method. This method correlates pump data sets into dimensionless form. Except in cases when engineers have four quadrant data for their pump, the typical modeling choice is to use data for a previously tested pump with a similar specific speed.

Some publications over the years have questioned the correctness of using pump specific speed as a correlating factor. This paper will explore this concern.

First, in order to correlate four quadrant pump data based on specific speed, true dimensional and dynamic similarity between pumps must exist. Modern insights of pump performance and pump specific speed will be given to assess the effectiveness of the assumption of correlation.

Second, some of the excellent four quadrant data used today was first published as far back as the 1930’s. The researchers could not have envisioned how their data would be used in modern waterhammer simulation. Indeed, many of the data sets used today were taken before Suter published his method in the 1960’s and before digital computers were created. As a result, it is not clear that the researchers placed a strong emphasis on appropriately calculating and reporting the specific speed of the pumps used in their testing. This paper will attempt to confirm or disconfirm whether the correct specific speeds were reported.

Finally, the Suter Method is a convenient and creative dimensionless formulation of pump data referenced to the test pump’s Best Efficiency Point (BEP). However, researchers over the years have taken to only publishing the dimensionless data and not the dimensional data behind the test. This makes it impossible to compare the waterhammer analyst’s pump to the original pump’s dimensional data, especially when the analyst’s pump is not operating near its own BEP – which is often the case.

These issues will be explored and recommendations will be given to improve how pumps are modeled in waterhammer simulation.


Pump Specific Speed and Four Quadrant Data in Waterhammer Simulation \u2013 Taking Another Look

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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