This paper reviews the current state of knowledge of rotordynamic forces caused by the discharge-to-suction leakage flows in centrifugal pumps. The indications that these flows could contribute significantly to the rotordynamics motivated the fabrication of an experiment in which measurements of rotordynamic forces would be made on simulated leakage flows in which the flow rate, clearance, eccentricity and other parameters would be exercised in order to understand the phenomena. Sample data is presented and demonstrates substantial rotordynamic effects which could be potentially destabilizing. The rotordynamic forces appear to be inversely propertional to the clearance and change significant with the flow rate
