PSI - Issue 20

Nickolay Ovchinnikov / Procedia Structural Integrity 20 (2019) 113–118 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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two existing technological schemes of drainage, which differ from each other in the length of pipelines and the number of shut-off valves. In addition, the low values of the determination coefficients R 2 of the linear regression equations derived from the approximation of the experimental dependences Q=f(Δ) (Fig. 1, a) and P=f(Δ) (Fig. 1, b) linear tre nd, due to the structural feature of the sectional pump.

b

a

Fig. 1. (a) The dependence of the axial displacement of the rotor from the pump (a) and the outlet pressure (b) from it and their approximation by a linear trend

It is well known section pumps are equipped with a hydraulic balancing unit, consisting of a ring and a disk, the main functional purpose of which is to balance the rotor axially with the help of water energy passing through the end gap between the above elements of the hydraulic balancing unit, and then through the discharge pipe, which is usually connected to the suction pipe of the pump. In practice, during the operation of the sectional pump, the end gap can both increase and decrease, thereby affecting its hydraulic parameters in different ways, as shown by Ovchinnikov et al. (2017) and Vikulov et al. (2017). Thus, we state that the reduction of hydraulic parameters of the sectional pump is not always associated with an increase in the axial displacement of the rotor. In the course of statistical studies, it was also found that the values of the rotor axial shift in addition to the hydraulic parameters are also poorly correlated and with RMSV vibration (υ) bearing units of the pumps studied (Fig. 2, a, b).

b

a

Fig. 2. (a) Linear dependences of the axial shift of the rotor on the vibration velocity of the rear (a) and front bearing assembly (b) and their approximation by a linear trend