| Abrasive water jet is a new processing method. The characteristics of the abrasive water jet system are simple, low cost and high cutting efficiency. Abrasive water jet has been widely used in cleaning, derusting, cutting and broking rock. In abrasive water jet system, the geometric structure of nozzle and the conditions of jet has an important effect on jet performance. The nozzle is the direct component which forms the mode of water jet. It influences directly flow characteristics and dynamic performance of water jet. The water jet has different effects under different conditions. Therefore establishing the relationship between nozzle structure parameters and jet flow characteristics on the basis of optimization nozzle geometric structure and selecting the best jet conditions are meaningful to improve jet efficiency.The numerical simulation of the straight-cone nozzle in the submerged condition of pre-mixed and post-mixed abrasive jet is carried out by using FLUENT software. As for pre-mixed abrasive jet, the influence of the structural parameters of the nozzle: convergent angle, nozzle exit diameter, the length of nozzle exit cylindrical section to diameter ratio and the different performing conditions: the diameter and volume fraction of the abrasive, the inlet pressure, ambient pressure, standoff distance on the flow characteristics of the abrasive jet is analyzed. The results show that the axial velocity and pressure of the jet decrease with the increase of the convergent angle. The jet has the best performance whenαis13o . The axial velocity and pressure of the jet increase with the increase of nozzle exit diameter. Nozzle length-diameter ratio has a little effect on jet. The jet has good performance when the diameter of abrasive is large and volume fraction is low. The axial velocity and pressure of the jet increase greatly with the increase of the inlet pressure. The axial velocity and pressure of the jet decrease greatly with the increase of the ambient pressure. The axial velocity and pressure of the jet have maximum value when the standoff of the jet is 100d. As for post-mixed abrasive jet, the influence of the nozzle structure parameters: the diameter and length of the mixing chamber, the length of mixing tube and the different conditions of jet: the protecting gas and the inlet velocity of protecting gas on flow field characteristics of jet is analyzed. The results show that jet has good performance when the nozzle has large diameter, small length mixing chamber and long mixing tube. The protecting gas makes jet performance improved, its protective effect is enhanced when increased. The axial velocity and pressure of jet is the largest when the velocity of protecting gas is 250m/s.
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