Numerical Investigation of Fluid Flow Mechanism in the Back Shroud Cavity of a Centrifugal Pump

Liu

Proceedings of the Institution of Mechanical Engineers, Part A:

et al. 2022

To explore the pressure distribution characteristics of pump chambers, and the law governing the axial force in a particle-laden flow centrifugal pump, a semi-open impeller centrifugal pump was selected as the research object. The particle model and heterogeneous model were used to develop the numerical calculations of the particle-laden flow field within the centrifugal pump. For the liquid phase we adopted the shear–stress–transport (SST) turbulence model, while for the solid phase we adopted the discrete phase zero equation model. The external characteristics, pressure distribution and axial forces were compared and analyzed (1) for a constant solid particle diameter, d, of 0.1 mm and particle volume fractions, Cv, of 0, 1, 5, and 10%, and (2) for a constant particle volume fraction, Cv, of 10% and solid particle diameters, d, of 0, 0.01, 0.1, and 0.5 mm. The correlations between the particle volume fractions and solid particle diameters with the pump chamber pressure distributions and axial forces were obtained. The results show that when Cv increased from 1–10%, or d from 0.01–0.5 mm, the pump head and efficiency decreased continuously under the same flow rate. At the same time, larger particle volume fractions resulted in larger pressures at the same radius, while for larger solid particle diameters, smaller pressures were obtained at the same radius. Under the same flow rate, when Cv increased from 1–10%, the total axial force of the centrifugal pump increased, but it was smaller than what was achieved under the clean-water condition. When d increased from 0.01 to 0.5 mm, the total axial force of the centrifugal pump decreased. This study provides a reference for the calculation and balance of the total axial force in a particle-laden flow centrifugal pump.

Section: Electronic Submissionmentioning

confidence: 99%

Study on pressure distribution of pump chamber and axial force in particle-laden flow of centrifugal pump

Liu

Proceedings of the Institution of Mechanical Engineers, Part A:

et al. 2022

“…In other words, the two are basically consistent, which can provide a reliable foundation for the following research. [6][7][8] show that at the low-flow working condition (0.8 ), there is a clockwise eddy current rotating in the corner area between the volute and the pump cover, with liquid flowing from the pump cavity to the volute at the corner area between the volute and the impeller at the 0° and 180° angles. At the same time, there is a counterclockwise vortex at the axial center near the wheel load.…”

Section: Fig 4 Centrifugal Pump Experimental System Schematicmentioning

confidence: 99%

“…In deriving this formula, it is considered that the pump cavity liquid has no radial leakage flow and that the liquid in the pump cavity rotates at one-half the rotational angular velocity of the impeller [4,5]. Debuchy [6] studied a turning static disk system core of cavity flows using experimental measurements and carried out a comparative analysis and theoretical calculation. Salvadori [7] performed a CFD numerical simulation of a multistage centrifugal pump and pointed out that to calculate the centrifugal pump axial force accurately, a detailed analysis of the flow characteristics of the fluid on the side of the impeller cover-plate cavity must be included.…”

Section: Introductionmentioning

confidence: 99%

Numerical analysis of the flow mechanism and axial force characteristics of the cavity in a centrifugal pump with a front inducer

Zhang¹,

Dong²,

Chen³

2020

J. vibroeng.

At three flow conditions (0.8 , 1.0 , and 1.2), the centrifugal pump cavity with front inducer was expanded at 0°, 90°, 180°, and 270°, and a flow path analysis of the axial cross section at the four angles was performed. This revealed that the circumferential and radial velocities of the liquid in the pump cavity along the same angle at different radii follow an axial and radial variation law to different degrees. The pump cavity center axial liquid velocity component along the radial distribution at different angles was analyzed, and liquid pressure in the pump cavity along the radial distribution was numerically analyzed from different points of view. The mean pump cavity pressure was plotted along the radial distribution curve, and a detailed numerical calculation of the axial force of the centrifugal pump and pump cavity was developed. The influence of flow conditions on the liquid flow mechanism and axial force characteristics in the pump cavity was thoroughly discussed. The results showed that liquid flow in the centrifugal pump cavity with the front inducer is mainly restricted by the main flow of the volute. The liquid eddy current in the pump cavity is mainly concentrated near the volute and the hub at 90° and 180° angles, and the higher the flow rate, the larger is the area of the side vortex of the impeller-cover plate, and the smaller is the area of the side vortex of the pump-cover plate. When the flow rate increases, the flow direction of the eddy current at the same angle in the pump cavity remains unchanged, but when the flow rate becomes too high, the flow direction of the eddy current at the same angle in the pump cavity changes. When the range of circumferential and radial partial velocities decreases, the rotational angular velocity increases, and the pressure decreases. At low flow rate, the larger the area of the volute corresponding to the pump cavity, the higher the speed becomes. The axial force in the pump cavity is the most important factor determining the axial force of the centrifugal pump.

Proceedings of the Institution of Mechanical Engineers, Part A:

“…In the case of high pressure, the axial force value occasionally attains to hundreds of tons, 1-3 the over large axial force could cause severe problem, it has exceeded the efficiency, wear and other factors, and becoming a determining factor for stable operation of the multi-stage pump. In order to decreasing the axial force of multistage pumps, using the auxiliary devices to balance the axial force is necessary, 4-6 the most common auxiliary balance devices are balance discs and balance drums. Makay E et al 7 counted the failure data of large boiler feedwater pump, and the pump equipped with auxiliary balance devices, which are balance disc and balance drum.…”

Section: Introductionmentioning

confidence: 99%

Study on the balance force regulation method of multi-stage pump balance drum system

Chen

Lihuan

Zhipeng³

et al. 2023

Balanced drum systems are widely used in high-pressure multi-stage pump axial force balancing mechanisms. When the pump working, the fluid (solid-fluid mixture) collides with each other or rubs against the pump case, and the balance drum is affected by this situation for a long time, so wear of the balance drum gap occurs from time to time. The first is to study how the axial force of the multistage pump changes at different balance drum gap sizes in this paper. Based on the energy equation and momentum equation, and on the basis of maintaining the original balance force unchanged, a new equation of resistance pressure difference relationship is established. The corresponding relationship between balance drum gap and balance pipe orifice plate is obtained by solving this equation. The result shows that the larger the balance drum gap, the greater the balance drum balance force decreases obviously, and the multistage pump residual axial force increases in multiples. The adjustment formula of balance force can be used to obtain the radial size of the balance pipe orifice plate under different balance drum gap, when the gap increases, to keep the balance force constant, the diameter of the orifice plate should be increased gradually. After adjusting the balance force, the fluid velocity uniformity and velocity average angle of balance pipe increases, the flow pattern in the pipe becomes uniform, the gap leakage increases and the pump efficiency decreases. The pump hydraulic properties and balancing the axial force have an opposing relationship, that is, by promoting the drum balance force, the pump hydraulic properties will be reduced. Due to processing balance drum is complex, frequent replacement is time-consuming and costly, so this article provides a handy approach for enhancing the balance force of balance drum, the results of the study can provide guarantees for the balance drum system optimization and long period stable operation of the multistage pump.