Abstract

The paper deals with the turbulent flow through the fałe clearance, which is a characteristic element of the flow system of the disk which relieves the axial force in a multi-stage centrifugal pumps. The presented description illustrates the automodelling flow, i.e. the square dependence of hydraulic resistances on the flow rate, applying the model k—ε and making use of the Tasc-Flow program of calculations. The essential aim was to compare the pressure fields in both these descriptions. The pressure field decides  about the value and direction of the hydrodynamic moment affecting the walls of the clearance. The hydrodynamic forces and moments in the sealing clearances influence essentially the dynamic properties of the rotor of centrifugal pumps. The results of calculations have been compared basing on a numerical example with the same assumed geometry of the clearances, the same flow rate and the same pressure drop. The pressure fields obtained by means of both methods of calculations have been presented graphically, providing numerical values of the calculated axial forces and moments, as well as the direction of their activity. Moreover, for the selected cross-section of the clearance the fields of radial and spherical speeds have been given. The coefficient of the inlet resistance and continuous resistance in the clearance, the application of which in the description of the automodelling flow provided the pressure field have been calculated similarly as in the case of applying the model  k—ε. As we see, in order to obtain correct results, the description of the automodelling flow ought to differentiate the coefficient of continuous resistance along the perimeter of the clearence.