No abstract

No abstract

The discharge process of granular material from a wedge‐shaped feed hopper was numerically simulated using a 3D discrete element method. The effects of particle size, feed pipe, side and rear wedge angle on the discharge performance were investigated in terms of flow pattern, discharge rate, and stability. The results show that with larger particle size the granular flow pattern gradually transforms from mass flow to edge flow where the flow rate decreases and the discharging integrity and stability become worse. The presence of the feed pipe reduces the discharge rate and stability. The increase of the feed pipe diameter will diminish the discharge rate and enhance the discharge stability. Both the side and the rear wedge angle have a certain effect on the discharge performance. The effects of feed pipe, side and rear wedge angle on the discharge stability become more significant with larger particle size.

The characteristic of sediment erosion of the blade in a double-suction centrifugal pump is mainly studied because the blades of double-suction centrifugal pumps are widely observed to suffer severe erosion damage in water intake projects along the Yellow River. In order to clearly present the evolution of blade-erosion area for different sediment properties in real conditions, the experiment with multiple layers of paint method is designed. The obtained results show that the leading edge of the blade, suction side of the blade inlet, suction side of the blade outlet and pressure side of the blade outlet are easy to be observed with erosion. More important, relationships between the eroded area and operation time by using hyperbolic tangent function are firstly established, and this function can be used to predict the development of the eroded area of blades in long operation. The first section in your paper

Prediction of erosion wear in double-suction centrifugal pumps is studied numerically using an improved erosion model (EM). Experiments are also performed to verify the improved EM’s prediction ability. In the experiments, painted layers of five colors are applied to the blade surfaces using spray guns to show the erosion wear distribution, where the colors and the order are selected based on the simulated results. In simulations based on the Oka model, the small-angle scratching effect is specifically added to the improved erosion model (called the Qian EM here). For the chosen double-suction centrifugal pump, the Oka EM and the Qian EM are used to predict erosion wear, including the wear area and intensity. Both EMs effectively predict the erosion areas of the leading edge, the suction side inlet part and the pressure side outlet part of the blade, but the Qian EM shows better ability to predict the erosion area of the outlet part on the suction side. Additionally, the erosion intensity seems more reasonable with the Qian EM. Inclusion of all different particle sizes in the numerical simulations is found to be necessary to predict erosion wear accurately because each single particle size may provide important information.