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In order to study the influence of a balance hole's diameter on the cavitation performance of low specific-speed centrifugal pumps, a centrifugal pump with a specific speed of 0.301 was selected as the research object. The pump's cavitation performance, distribution of cavitation vapor in the impeller, and axial force on the impeller were studied with the change in diameters of balance holes. The results show that with the increase in the diameter of balance holes, the cavitation number σ3% of the low specific-speed centrifugal pump became small, the pressure in the mechanical seal cavity dropped gradually, and the flow velocity in balance holes was reduced. As cavitation occurred in the impeller, the diameter of balance holes not only affected the absolute value of the axial force but also affected the direction of the axial force. [ABSTRACT FROM AUTHOR]

In order to reduce the axial force of the semi-open centrifugal pump with low specific speed, the influencing factors of the axial force of the semi-open centrifugal pump are analyzed and studied by means of orthogonal experiment by combining numerical analysis. The blade tip clearance and balance hole diameter are selected as experimental factors, and each factor takes 5 levels to carry out orthogonal design. SST k-ω Turbulence equation is used to calculate the axial force of the semi-open centrifugal pump. According to the comparison between the calculated results and the experimental results of the original model, it is found that the head and efficiency change within 5%, so the numerical simulation method is feasible. Based on L25 (5²) orthogonal table, 25 groups of experimental schemes are designed, and the optimal scheme is obtained by analyzing the numerical simulation results of 25 groups of experimental schemes. The results show that by reducing the tip clearance and establishing the balance hole, the back cavity pressure increases significantly, and the axial force of the centrifugal pump decreases greatly, the maximum reduction is 440.59 N, accounting for 45.6% of the total axial force of the original model. At the same time, it has little effect on pump performance, efficiency only reduces by 3.76%, and the head reduces by only 0.3%. [ABSTRACT FROM AUTHOR]

This paper studies the flow characteristics and disk friction loss of the rear chamber in a centrifugal pump at a design flow condition with six values of the balance holes at diameters from 0 to 12 mm. The results show that the turbulent boundary layer in the rear chamber is greatly affected by the leakage flow. When the balance hole diameter increases, the flow characteristics of the rear chamber is mainly restricted by the mainstream flow field of the volute. However, when the balance hole diameter is larger than the design value, the disk friction loss of the rear chamber remains basically unchanged. On the contrary, when the balance hole diameter is smaller than the design value, the larger the balance hole diameter the smaller the friction loss of the disk in the rear chamber area. The results of this paper provide a reference for reducing axial force and stable operation of a centrifugal pump. [ABSTRACT FROM AUTHOR]

In order to study the influence of a balance hole’s diameter on the cavitation performance of low specific-speed centrifugal pumps, a centrifugal pump with a specific speed of 0.301 was selected as the research object. The pump’s cavitation performance, distribution of cavitation vapor in the impeller, and axial force on the impeller were studied with the change in diameters of balance holes. The results show that with the increase in the diameter of balance holes, the cavitation number σ3% of the low specific-speed centrifugal pump became small, the pressure in the mechanical seal cavity dropped gradually, and the flow velocity in balance holes was reduced. As cavitation occurred in the impeller, the diameter of balance holes not only affected the absolute value of the axial force but also affected the direction of the axial force.

In order to study the impact of different leakage rates on the performance and axial force of the impeller of a single-stage centrifugal pump, a combination of experiment and theoretical analysis was used to analyze the performance of the single-stage centrifugal pump at full flow and the law of axial force changes. Analysis and research. The IS200-50-45/4 single-stage single-suction centrifugal pump was selected to build a test platform. Under the same test conditions, the impeller opening 3 and 5 balance holes were tested respectively; at the same time, the collection The performance of the centrifugal pump and the measured value of the axial force under different number of balance holes, the performance of the centrifugal pump through the test data. [ABSTRACT FROM AUTHOR]

In this paper, the influence of the specific area of balancing hole on the cavitation performance of high-speed centrifugal pump is studied by numerical method. The results show that in the initial cavitation stage, with the increase of the specific area, the head and efficiency of the pump decreases, and the shaft power increases in a small range. The specific area of the balance hole can change the magnitude and direction of the rotor axial force. With the increase of the specific area, the anti-cavitation performance of the pump is weakened, especially when the specific area reaches a certain value, the vortex flow appears in the balance hole, which causes serious distortion of the flow condition at the inlet of the centrifugal impeller. Meanwhile, cavitation also occurs in the balance chamber and is mainly concentrated near the hub of the centrifugal impeller. [ABSTRACT FROM AUTHOR]

The diameter of the impeller balance hole in a centrifugal pump is closely related to axial force. Thus, to select the appropriate diameter of a balance hole is crucial for balancing the axial force of the centrifugal pump. After the validation of the CFD method and the grids independence study, the characteristics of flow in the hub cavity have been analyzed in 4 cases with different diameters of balance holes. The leakage rate of the liquid in the hub cavity of the centrifugal pump is calculated and compared with the test result. According to the research, when no balance hole exists, the distribution of liquid velocity in the core area of the hub cavity exhibits axial symmetry, and the circumferential velocity component is approximately 0.4 times of the impeller's rotational speed. When the balance hole exists, the distribution of liquid velocity in the hub cavity does not exhibit axial symmetry, and the circumferential velocity component is larger than 0.4 times of the impeller's rotational speed. The radial leakage velocity on the turbulent boundary layer of the pump cover will increase with the increasing diameter of the balance hole. [ABSTRACT FROM AUTHOR]

The article presents a study which analyzes a multistage centrifugal pump including leakages and balance holes through experimental and computational fluid dynamics investigation.

The multistage centrifugal lifting pumps are widely used for deep-sea mining to achieve high-head vertical transportation. However, the axial thrust caused by the multistage structure probably exceeds the carrying capacity of the deep-sea lifting pump. Mounting balance holes on the impeller reduces the axial thrust but also affects the pump's hydraulic performance. In this research, the deep-sea mining pump's axial thrust and hydraulic performance were studied. A computational fluid dynamics model of a two-stage centrifugal pump was established employing the whole-flow-field method. Numerical simulations on the transportation of pure liquid and solid–liquid mixtures were then carried out for an actual mining pump. Results reveal that the influence of balance hole position on hydraulic performance or thrust is insignificant. A larger hole diameter, contributing to an increased flow rate and ability to balance axial thrust, however, causes more flow losses and worse hydraulic performance. Furthermore, a test prototype pump was developed, and a non-destructive measuring device was exploited to acquire hydraulic parameters and axial thrust. The experimental results reveal the effectiveness of the proposed balancing scheme and numerical method. These findings could provide analytical methods and theoretical support for designing lifting pumps in deep-sea mining. • A balancing hole design method for centrifugal pump impeller is proposed. • A CFD model was established to predict the axial thrust and hydraulic performance. • A nondestructive axial thrust measuring method for the multistage centrifugal pump is presented. [ABSTRACT FROM AUTHOR]

Thrust balance system with balance holes is proposed for the dynamic stability of high-speed rotating machinery. The effects of the geometric variables on the leakage flow were identified numerically, and the heat transfer characteristics of the thrust bearing were analyzed. The leakage flow passing through the balance holes reduces the pressure in the thrust cavity and the axial thrust force acting on the rotating components by 26%, enhancing the dynamic stability. The dynamic performance can be calculated from a correlation that predicts the thrust force ratio, and thermal stability can be determined by predicting the cooling effect of the thrust bearing. In addition, a contour map is provided to evaluate the design feasibility of balance holes in various operating environments. • Flow and thermal characteristics in thrust cavity with balance holes were analyzed. • Effects of balance holes on dynamic stability was identified by parametric study. • Correlations were proposed to establish the design criteria of balance holes. • Thrust force ratio was improved by up to 26% with ensuring thermal stability. [ABSTRACT FROM AUTHOR]

Centrifugal pumps are prone to vibration due to unstable impeller forces under gas–liquid two-phase conditions. The balance hole can balance the axial force on the impeller and improve the operation stability of the pump. In this study, the influence of the balance hole on the performance of the multiphase pump is studied. By parameterizing the balance hole, the influences of the radial position, circumferential position and diameter of the balance hole on the external characteristics, gas-phase distribution and axial force of the multiphase pump are investigated. Results show that the balance hole degrades the centrifugal pump performance at small gas volume fraction (GVF). At high GVF, when the balance hole is located in the gas phase accumulation zone and the diameter is above 6 mm, the performance of the centrifugal pump will be improved. The balance hole can improve the distribution of gas-phase in the impeller, but the effect is limited to the local area around the balance hole. The effect of the balance hole on the axial force weakens as the centre position of the balance hole moves from the impeller inlet to the impeller outlet, increases with increased hole diameter and is less influenced by circumferential position. • Effect of the balance hole on the external characteristics of a gas–liquid two–phase centrifugal pump is investigated. • The balance hole can improve the distribution of gas-phase in the impeller, but the effect is limited. • The radial position of the balance hole has great influence on axial force than diameter and circumferential position. [ABSTRACT FROM AUTHOR]