Development of New Vertical Line Shaft Pumps

ANDRITZ has developed a modern design system consisting of CAD-based geometry definition, hydraulic optimization by means of numerical flow simulation, and finally analysis of mechanical behavior.

For an initial impeller or guide vane design, TURBOdesign1 is now extensively used within ANDRITZ. Our experience is that TURBOdesign1 provides good solutions in a very short period of time, especially when starting from scratch.

The hydraulic behavior is then evaluated by solving the full 3D-Navier-Stokes equations in combination with a robust turbulence model.

Based on the initial TURBOdesign1 solution, the blade profile is further optimized by experienced designers and interaction with the stationary components (e.g. casing) must be tuned. Finally, the progress in hydraulic design is verified by model test results.

Application of TURBOdesign1 to Pump Design

TURBOdesign1 was introduced at ANDRITZ for hydraulic development of a new vertical line shaft pump (Fig. 1). This type of pump is typically used for irrigation and the cooling water supply to thermal power plants.

Due to changing requirements, the pump operating range had to be shifted to higher flow rates and higher heads. Thus, there was a need to develop new runner blades and new guide vanes.

The hydraulic designs were verified by computational fluid dynamics (CFD,) including all flow-relevant components (s. Fig. 2).

An extensive series of measurements was carried out in the ANDRITZ in-house hydraulic laboratory (ASTRÖ) on a fully homologous model. These experiments provided performance data (flow rate, head, power, efficiency), cavitation observations, hydraulic forces (axial thrust, radial force, and momentum) and stability limits (e.g. pressure pulsations).

Compact Design:

Compared with the old reference pump, the new design is characterized by a smaller size and by significantly higher blade loading, hence providing greater head and flow rate. Furthermore, the efficiency at the design point (OP1) could be improved.

Enhancement of Cavitational Limits:

Regarding cavitation, the NPSH required curve of the reference design had to be shifted to higher flow rates in order to avoid pressure side cavitation in start-up condition.

Finally, the new design fulfilled the fundamental condition NPSHplant ≥ NPSHrequired for the whole operating range and the measurements were completed with a successful acceptance test, witnessed by our customers.