DYNAMIC TESTS ROTORS PUMP OF CYLINDRICAL AND DISK CONFIGURATION IN SLOTTED SEALS

Abstract

Centrifugal pumps are used in a wide variety of industries and agriculture in all countries of the world. In connection with the widespread use of centrifugal pumps, the issues of working out their design schemes, which provide high indicators of durability and vibration reliability, continue to be relevant. Hydrodynamic forces in the gap seals of the pumps have a significant effect on the vibration activity of the rotor as a whole. Significant hydrodynamic forces in the gaps of non-contact seals of centrifugal pumps can lead to a loss of dynamic stability of the rotor and self-oscillations of the rotor (which is unacceptable), and vice versa - to significantly reduce the vibration activity of the rotor in the seals. Theoretical and experimental studies by various authors allowed to establish the structure of hydrodynamic forces and to determine the values of radial force coefficients. There was a need for further practical research in order to obtain reliable information about the influence of the geometric shape of the rotor on its ability to self-center in seals at different angular speeds of rotation, up to the loss of the rotor's dynamic stability. On a specially created laboratory experimental stand, the authors of this work obtained the amplitude frequency characteristics (frequency response) of forced radial-angular oscillations of self-aligning in slotted seals of pump rotors of cylindrical and disk geometric configurations at different pressure drops of the working fluid on the seals. Amplitude frequency characteristics of forced radial-angular vibrations of the rotor were also obtained with neutralization of the swirl of the working fluid at the entrance to the seal. The frequency response of the rotors obtained experimentally made it possible to determine the critical angular velocities of the radial and angular oscillations of the rotors in the seals, as well as the limits of their dynamic stability. The angular velocities of the inherent radial and angular oscillations of the rotor in the seals, as well as the limits of their dynamic stability, were calculated according to theoretical formulas. Comparison of theoretical and experimental values indicates their good quantitative agreement. A conclusion is drawn regarding the higher dynamic stability of the rotor of the disc geometric configuration compared to the cylindrical configuration. When designing centrifugal pumps with an impeller selfinstalling in slot supports - seals, one should strive for a disk geometric configuration of the impeller.