Problem

Why do the turbine extended results (as seen in the Extended Node Data tab of the Transient Results Viewer, or in the text output report) stop at the time when the gate is 20% open in HAMMER? Why are the turbine results truncated?

Solution

The four-quadrant curves for turbines have information for different gate openings. However, 20% gate opening is as low as it goes. That means it is not possible to compute or interpolate the turbine operating point when the wicket gates are less than 20% open, so what HAMMER does is linearly interpolate from the flow at 20% open down to zero flow (at the time when the operating rule says the wicket gates are 0% open). Without any four-quadrant turbine characteristic curves available for these gate openings, there is no way to compute the turbine behavior.

If you are using HAMMER V8i, the four-quadrant curves are listed in the file called QuadrantCurvesPredefined.txt, located in the HAMMER8 install folder. For example, you'll see that for the 60/230 (US/SI) curve, there are separate tables for each gate percentage, which start at 20%.

See Also

Using Turbines in Bentley HAMMER