Research on the mixing process of gas–liquid–solid multiphase flow in a high-pressure abrasive water jet (HP-AWJ) is of great significance in improving the performance of water jet cutting. In this paper, the Euler method-VOF model, a computational fluid dynamics (CFD) simulation method, is used to solve the multiphase flow of air–water in an abrasive water jet (AWJ). The Euler–Lagrange method is further used to study the multiphase flow of abrasive particles. The method considers the shape factor of the particle, uses the Rosin–Rammler function, and defines an effective model for the particle-to-wall wear model. By solving the velocity of the continuous phase and particulate phase in the AWJ cutting head, the problem of nozzle wear caused by particles is studied. Finally, the exit velocity of the AWJ and particle wear are investigated by varying the model’s parameters. The results show that the double abrasive tube model effectively improved the problem of one-sided wear inside the nozzle, and the tangential velocity of the air affected the acceleration process of the abrasive inside the nozzle, with smaller abrasive velocity resulting in less wear on the model. Simultaneously, the effects of the abrasive inlet tube and mixing chamber size on abrasive exit velocity and nozzle wear are analyzed. The results obtained provide valuable guidance for addressing the multiphase flow mixing issues in the AWJ, improving the abrasive acceleration process and extending the nozzle’s lifetime.

In order to ensure the blade strength of large-scale wind turbine, the blunt trailing edge airfoil structure is proposed, aiming at assessing the impact of the trailing edge shape on the flow characteristics and airfoil performance. In this paper, a Joukowsky airfoil is modified by adding the tail thickness parameter K to achieve the purpose of accurately modifying the thickness of the blunt tail edge of the airfoil. Using Ansys Fluent as a tool, a large eddy simulation (LES) model was used to analyze the vortex structure of the airfoil trailing edge. The attack angles were used as variables to analyze the aerodynamic performance of airfoils with different K-values. It was found that when α = 0°, α = 4°, and α = 8°, the lift coefficient and lift–drag ratio increased with increasing K-value. With the increase in the angle of attack from 8° to 12°, the lift–drag ratio of the airfoil with the blunt tail increased from +70% to −7.3% compared with the original airfoil, which shows that the airfoil with the blunt trailing edge has a better aerodynamic performance at a small angle of attack. The aerodynamic characteristics of the airfoil are affected by the periodic shedding of the wake vortex and also have periodic characteristics. By analyzing the vortex structure at the trailing edge, it was found that the value of K can affect the size of the vortex and the position of vortex generation/shedding. When α = 0°, α = 4°, and α = 8°, the blunt trailing edge could improve the aerodynamic performance of the airfoil; when α = 12°, the position of vortex generation changed, which reduced the aerodynamic performance of the airfoil. Therefore, when designing the trailing edge of an airfoil, the thickness of the trailing edge can be designed according to the specific working conditions. It can provide valuable information for the design and optimization of blunt trailing edge airfoil.

Machining of No. 45 steel (AISI 1045) becomes more vital due to its widespread use. In this study, machining performances of abrasive water jet machining (AWJM) of No. 45 steel, including material removal rate, notch depth, and nozzle wear rate, were obtained by experimental and computational results. The Taguchi L16 orthogonal array design was used to study the influence of process parameters on machining performance. The optimal material removal rate and notch depth were achieved when abrasive particle size, operating pressure, and abrasive feed rate were 80 #, 400 MPa, and 840 g/min, respectively. The optimal nozzle wear rate was achieved when abrasive particle size, operating pressure, and abrasive feed rate were 80 #, 400 MPa, and 260 g/min, respectively. When the abrasive particle size is 80 # (namely the mesh number is 80), the particle diameter is usually between 0.18 and 0.25 mm according to the corresponding relationship between the international standard mesh number and particle diameter. Analysis of Variance was conducted to evaluate the statistical significance of the experimental results. Using regression analysis, an empirical model was developed to predict the response values of the AWJM process. Multi-response optimization was then carried out using the Decision Engineering Analysis and Resolution method. The optimal parameter solution for a higher material removal rate, a bigger notch depth, and a smaller nozzle wear rate was achieved when abrasive particle size, operating pressure, and abrasive feed rate were 120 #, 400 MPa, and 870 g/min, respectively.

The velocity distribution at the deflector jet outlet significantly influences the pressure characteristics of the pilot stage, thereby affecting the dynamic performance of the servo valve. Conventional mathematical models fail to account for the influence of dynamic velocity distribution on pilot stage pressure characteristics, resulting in significant deviations from actual situations. As the deflector shifts, the secondary jet velocity distribution transitions from a symmetric to an asymmetric dynamic profile, altering the pressure within the receiving chambers. To address this, a dynamic skewed velocity distribution model is proposed to more accurately capture the pressure characteristics. The relationship between the skewness coefficient and deflector displacement is established, and the pressure calculation method for the receiving chambers is refined accordingly. A comparative analysis shows that the proposed model aligns most closely with computational fluid dynamics results, achieving a 98% match in velocity distribution and a maximum pressure error of 1.43%. This represents an improvement of 84.98% over the normal model and 82.35% over the uniform model, confirming the superior accuracy of the dynamic skewed model in pilot stage pressure calculation.

High-pressure abrasive water jet (HP-AWJ) cutting is a prominent technology for processing a wide variety of materials. The structural parameters of the nozzle are important for the cutting performance of the HP-AWJ. This paper combines an abrasive particle kinetic energy model and a wall wear model of the nozzle to determine the multi-phase flow of a HP-AWJ nozzle. The flow field structure of the nozzle was optimized using a parametric multi-objective structure optimization design method. A Multi-Objective Heat Transfer Search (MOHTS) was utilized to generate the corresponding mathematical regression model for multiple response results, and the optimal solution sets of Pareto values were further obtained. The optimal HP-AWJ structural parameters could be selected according to the weight influence of multiple response indicators.