Pump systems are widely used in engineering applications and are meticulously designed using numerous engineering calculations. Engineers strive to produce safer and more efficient pumps. These systems are dynamic, incorporating moving components such as shafts, impellers, and bearings, all subject to various dynamic effects. During the design phase of such systems, understanding how their dynamic characteristics will evolve with the design is crucial for ensuring safe and high-performance operation. In this study, modal analysis and rotordynamic analysis were performed on a rotor system, consisting of the shaft, impeller, and bearings, of a centrifugal pump system. A numerical model of this system was created using MATLAB. The moving rotor of the centrifugal pump was modeled using the Euler-Bernoulli beam theory. The impeller was represented as an equivalent disk after creating its 3D solid model, taking into account its polar and diametric moments of inertia. The ball bearings supporting the rotor were modeled using linear spring and damping elements. It is investigated how the natural frequencies and critical speeds of the rotor system changed for different distances between the two ball bearings used for shaft support and for various bearing stiffness values. Additionally, the presence of anti-resonance frequencies in the transfer frequency response functions between the impeller and the bearings was identified, and their variations with parameter changes were analyzed. The conducted parameter variations revealed that the natural frequencies and critical speeds changed significantly, and these changes exhibited different tendencies depending on the mode shapes. The results demonstrate that constructional design parameters in pump system rotors significantly impact the system's dynamic characteristics.
Murat Şen (Tue,) studied this question.