Abstract
The balancing holes in centrifugal pumps with seals mounted in both suction and discharge sides are one of the approaches used by pump manufacturers to reduce the axial thrust. The balance hole diameter directly affects the axial force of the centrifugal pump. The flow characteristics in the balance chamber are closely related to the balance hole diameter. However, research is not very clear on the internal flow of the balanced chamber, due to the small axial and radial sizes and the complicated flow conditions in the chamber. In this paper, we analyzed the influence of the balance hole diameter on the liquid leakage rate, flow velocity, and vortex motion in the balance chamber. The results indicated that when the balance hole diameter was lower than the design value, the volume flow rate of leakage flow was proportional to the diameter. The liquid flow rate and vortex distribution rules in the balance chamber were mainly associated with the coeffect of radial leakage flow in the rear sealing ring interval and the axial balance hole leakage flow. The research has revealed the mechanisms of leakage flow of the balance chamber in the centrifugal pump and that this is of great significance for accurate calculation and balancing of the axial force.
Highlights
Calculating and balancing the axial forces of a centrifugal pump are the main challenges in the pump industry in recent years
For the seals mounted in both suction and discharge sides of the impeller with balance holes in a centrifugal pump, the lateral chamber of the impeller back cover plate is composed to the rear chamber and the balance chamber. e balance chamber is connected to the impeller entrance through the balance hole which is widely employed to balance axial forces in a centrifugal pump [1, 2]
To calculate the axial force in the centrifugal pump, current theoretical formulas always assume that the liquid in the impeller cover plate lateral chamber has no leakage flow, and the liquid in the balance chamber has no rotational motion [3]. e numerical results of the axial force of the centrifugal pump, which is calculated from classical theory in given conditions, are inconsistent with the test results from the physical experiments [4]
Summary
Calculating and balancing the axial forces of a centrifugal pump are the main challenges in the pump industry in recent years. A numerical study found that the volume flow rate of the leakage flow directly affected the liquid pressure in the balance chamber, and the calculation of the impeller cover plate force (i.e., the axial force of the centrifugal pump) and an appropriate balance hole diameter could balance the axial force to its maximum [9]. E pressure distribution at the side of the impeller cover plate was obtained by numerical calculation, and the predicted axial force of the centrifugal pump was compared with the test results. Is paper refined the grids in the back cover plate lateral chamber during the grid independence study to eliminate the influence of the grid number on the flow field in the balance chamber area of the centrifugal pump.
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