Effect of nozzle inlet parameters on the dry granulation atomization process of Si₃N₄ ceramic bearing balls

Abstract

In this paper, the atomization characteristics of Si3N4 ceramic dry granulation affect the performance of Si3N4 ceramic bearing balls. In order to improve the dry granulation characteristics and the comprehensive performance of Si3N4 ceramic bearing balls, the atomization mechanism of the spinning nozzle used for Si3N4 dry granulation was studied in detail. The interaction between air and binder in the pressure-swirl nozzle is analyzed based on VOF method, the modified realizable [Formula: see text] turbulence model is used to simulate the flow field inside and outside the pressure-swirl nozzle, the effects of nozzle inlet parameters including the number of tangential inlets and the deflection angle of tangential inlets on the binder volume fraction, velocity distribution and pressure distribution are analyzed. The results show that when the number of tangential inlets increases from 1 to 4, the swirl strength of gas–liquid two-phase in the nozzle increases, the mean diameter of air core increases from 1.51[Formula: see text]mm to 2.01[Formula: see text]mm, and the spray cone angle increases from 18.5[Formula: see text] to 26.4[Formula: see text]. Besides, when the deflection angle of tangential inlet increases from 0[Formula: see text] to 15[Formula: see text], the swirl strength of gas–liquid two-phase in the nozzle with the deflection angle of tangential inlet of 10[Formula: see text] is the largest, and the mean diameter of air core and spray cone angle is 3.04[Formula: see text]mm and 30.7[Formula: see text], respectively. Based on the atomization experiment platform of the electric control fuel system, the mean diameter of air core and spray cone angle are measured, the micromorphology of Si3N4 particles is observed, which verifies the correctness of numerical simulation. When the Si3N4 particles are prepared by dry granulation, taking the atomization performance of nozzle into consideration, the pressure-swirl nozzle with 4 tangential inlets and 10[Formula: see text] deflection angle should be selected.