Optimum structure of a laval nozzle for an abrasive air jet based on nozzle pressure ratio

The effect of nozzle pressure ratio n on the flow field of an air jet was investigated to obtain the basis of nozzle design. The flow field structure and abrasive acceleration of these nozzles were numerically simulated via Fluent, which was verified by I-Scan and erosion experiment. It was concluded that n is the primary factor that affects nozzle structure design, n = 1.12 can generate a better flow field structure. The dynamic pressure of the jet was measured via I-Scan, and the range of dynamic pressure variation was low when n = 1 and n = 1.12. Improvements in the flow field structure are more advance to the abrasive acceleration. The abrasive was accelerated to the maximum velocity at n = 1.12. Thus, n = 1.12 is the most advantageous to abrasive acceleration and material erosion wear. For example, the erosion depth and volume corresponding to n = 1.12 at 15 MPa increased by 60% and 27% when compared to n = 5. (C) 2020 Elsevier B.V. All rights reserved.