“The essence of the problem of increasing the rotation speed of the centrifugal pump rotor and its influence on the operating process.”

Abstract

The article examines the operating principle of a centrifugal pump and provides a list of
necessary fittings for its effective operation. A mathematical equation is proposed to describe operation
of the centrifugal pump that allows to determinate the pump's theoretical head based on the kinematic
parameters of the fluid flow through the pump's impeller. The most common motors used to drive
centrifugal pumps are asynchronous electric motors. It is noted that a key feature of the centrifugal
pump is the presence of a rotor - a rotating shaft with various attached components. During operation,
the rotor is subjected to harmonic excitations in the form of forces and moments of inertia from
unbalanced masses, which cause its forced vibrations. The general mathematical model for increasing the rotational speed of the centrifugal pump rotor describes the motion of a continuous viscous fluid
using the Navier-Stokes equation. Expressions are provided that take into account local losses at the
inlet and outlet of the seals to increase the rotor's rotational speed. To enhance the rotational speed of the
centrifugal pump rotor, two-dimensional beam elements of type BEAM 188 were used. For modeling
the seal-supports, a combined element of type COMBI 214 was utilized. In the case of a simplified
calculation of the rotor's rotational speed, the direct stiffness of the seal-support was determined based
on the dependence for a short clearance seal. The analysis of amplitude-frequency characteristics shows
that cross stiffnesses as well as both direct and cross damping significantly affect the increase in the
rotor's rotational speed. It has been established that hydrodynamic moments become a significant factor
influencing the dynamic properties of the centrifugal pump rotor when it undergoes combined radialangular oscillations in the clearance seals of the rotor's flow path.