The Research Of Liquid Flow Characteristics In The Impeller Shroud Side Clearance Of Centrifugal Pump

In this paper, the IS150-125-315single-stage single-suction centrifugal pump is selected for the study. First, the performance and the liquid pressure in the pump back-chamber were measured. Then, the numerical calculation of the flow field was carried out in the whole pump flow channel. On basis that the numerical simulation results of the pump performance and the liquid pressure in pump back-chamber are nearly identical with the experimental results, through numerical calculation, the axial distribution of dimensionless circumferential velocity component and dimensionless radial velocity component of the pump back-chamber liquid was obtained at the same radius with the angle0°,90°,180°,270°and at the same angle with the radius110mm,130mm,155mm,162mm. And further studies the effect on the performance of the centrifugal pump for balance holes diameter, that the axial distribution of dimensionless circumferential velocity component and dimensionless radial velocity component of the pump back-chamber liquid was obtained at the same radius with the angle0°,90°,180°,270°and at the same angle with the radius110mm,130mm,155mm,162mm. Calculation of the back-sealing ring clearance leakage is in progress at last, study the effect on it for the balance holes diameter.The results show that the pump back-chamber liquid pressure along the radial in the rating is less than the design flow, the pressure distribution are large differences among the different angles, along radial section7of the volute is approximate parabolic distribution, but in the greater than design flow, pressure tend to be more equal along the different angles, and the distribution is linear. Flow core area and liquid leakage exist in the liquid flow of pump back-chamber. The change of dimensionless circumferential velocity component and dimensionless radial velocity component is large at the same radius in the flow core area. However, the change has certain regularity in the axial direction at the same radius, especially that the dimensionless circumferential velocity component is almost constant. The ratio k of the rotational angular velocity of liquid and rotational angular velocity of impeller is influenced by the leakage of back-chamber liquid in flow core area. k is not constant. Centrifugal force of the flow core area liquid fairly equals the force caused by the racial differential pressure. Radial velocity component is relatively small and its performance is the same as the rigid body rotation. When the flow is0.8Qsp,1.0Qsp,1.2Qsp, and r>0.7, the average value of k is0.41,0.48,0.54. Average velocity of the flow core area liquid dimensionless circumferential velocity component increases with the increase of balance holes diameter along the axial, less than zero absolute value of dimensionless radial velocity component along the axial increases with the increase of balance holes diameter near the pump cover. When r=0.7, the change of k and vr almost has nothing to do with the radius and tend to be constant. The liquid leakage of back-sealing ring clearance will first increases with the increase of balance holes diameter, but the balance hole diameter increases to a certain value is maximum. Followed, leakage is a downward trend with the increase of balance holes diameter. The change of the liquid flow nearby the outside of rotating impeller back-cover and stationary pump cover is very large. Flow core area is only a transition zone. Thus using the liquid flow phenomena of flow core area to describe the liquid flow of pump back-chamber is debatable. Liquid in pump back-chamber has no axial flow and consists of rotary shear flow and differential pressure flow. It can be considered as a two-dimensional viscous laminar motion. This paper can provide theoretical basis for the accurate computation of the centrifugal pump axial force.