Abstract
In pumps and water turbines, the rotordynamic force and moment can cause shaft vibrations. The fluid force which acts on the backshroud of the impeller and runner generates the fluid moment, and it can cause the whirling motion of the rotor. We made a test facility in which the backshroud was modeled by a rotating disc and could observe the whirling motion of the rotor. By the simulation of the flow around the whirling disc, we found that the fluid moment acted on the disc. Therefore, it was releaved that the rotordynamic fluid moment excites the whirling motion.
