Regenerative turbine pumps are preferred in applications where high pressure and compact design are desired. The typical pressure versus flow or head-capacity curve of a regenerative turbine is steep, so these pumps can easily overcome line restrictions, such as temporary blockages or the friction of long lengths of piping or tubing. Steep pressure characteristic means that large changes in pressure or restriction have relatively little effect in flow rate. Another important characteristic of the regenerative turbine is pulsation free flow.
For high-pressure applications, positive displacement pumps (PD) like piston, diaphragm, or gear pumps are also an option, however they typically suffer from two significant drawbacks. Many PD pumps have a pulsating flow output that can cause inconsistent performance in the end application, as well as, vibration, mechanical damage, and cavitation effects. Positive Displacement pumps also tend to be mechanically intensive and often have friction and wear problems that increase maintenance and repair costs. Regenerative turbines do not suffer from either of these issues.
Within the realm of available regenerative turbine pumps, Aavid’s pump vendor has added several features to provide additional capability and functionality. The first is the use of a double-sided floating turbine impeller design (see Figure 4). As pressure develops equally on both sides of the impeller, a thin hydrodynamic fluid film forms between the impeller and the casing. This film helps prevent impeller wear and causes the impeller to self-adjust to its optimum axial position.