Effect Of Sediment-water Mixture On Cavitation Erosion And Abrasive Wear

Damage caused by cavitation erosion and abrasive wear is bad to discharge structure of water conservancy project and hydraulic machinery in the river with high concentration sediment.Experiments were carried out to study the effects of sediment properties and impingement angle on cavitation erosion and abrasive wear of typical materials of water conservancy project with or without a new paint coating by a vibrating probe to match a custom-made particle-moving device,and the mechanism of cavitation erosion and abrasive wear was discussed,in addition,the damage were compared.The main research contents and conclusions are as follows:(1)According to the test requirements,we design the particle-moving device which can be better used to the vibrating probe for test of cavitation erosion and abrasive wear.Part of the traditional abrasion test is innovated so as to study the problem in a more extensive way.(2)The effects of time,sediment properties,impact angle and compressive strength on cavitation erosion and abrasive wear of brittle materials have been investigated.Experimental results show that the cavitation erosion process of brittle materials soon reached the erosion stability period,there is no typical the erosion incubation period for plastic materials.The damage increases first abruptly and then increases slowly with increasing particle size of sediment and sediment concentration,and it has no obvious peak,there is no the critical particle size and the sediment critical concentration for plastic materials.For all concrete samples,the damage is highest at 90° impingement angle,and lowest at 30° impingement angle,in accordance with erosion rule of brittle materials.The compressive strength of samples have influences on cavitation erosion and abrasive wear,but not the deciding factor.The damage of samples have closed relation with the structure of samples.(3)The protective effect of new coating first increased and then weakened with increasing particle size of sediment and sediment concentration.The protective effect of the new coating on the cutting action in the tangential component of energy is greater than the protective effect of the impact action in the normal direction.The protective effect weaken with increasing impact angle.The coating has better protective effect on cement mortar in the sand laden flow with small particle size,low sediment content and low angle.(4)NaCl concentration has a specific threshold concentration on the impact of brittle materials and plastic material 45 # steel,respectively 2.0% and 3.5%.The synergistic effect between the mechanical abrasion of sediment particles on the metal t and the electrochemical corrosion of the chloride on the metal is greater than the inhibitory effect of the fine sediment on the metal abrasion due to the viscosity of the water body.The addition of chloride salt makes the damage of cement mortar abrasion is much greater than that of 3.5% NaCl containing medium,which greatly weakened the abrasion resistance of cement mortar.