Numerical investigation of performance characteristics in a bearingless direct-drive centrifugal pump under extreme operating conditions

Abstract

Traditional centrifugal pumps have limitations such as bearing wear and mechanical seal failures resulting from high-speed operations, which lead to a notable reduction in system efficiency. To overcome these limitations, centrifugal pumps driven by bearingless motors are employed. However, the absence of shaft constraints in such setups causes the impeller rotor to experience offset and tilting, thereby affecting pump performance and potentially causing system malfunctions. Thus, the bearingless direct-drive centrifugal pump (BDDCP) characteristics under extreme operating conditions need to be quantitatively analyzed. This study obtained a suitable turbulence model through experiments and subsequently designed three extreme operating conditions: different flow rates, impeller offset positions, and impeller tilt angles. The velocity field, external characteristics, and radial water excitation force were comprehensively analyzed. The results showed that flow changes greatly impact the BDDCP performance, while tilt angle changes slightly impact the BDDCP performance. These results can serve as a reference for subsequent research on BDDCP under extreme operating conditions.