Parameter optimization of the MQL nozzle by the computational fluid dynamics

Abstract

Minimum quantity lubrication (MQL) has achieved a good effect in precision machining. The geometric parameter of the nozzle has an important effect on the performance of MQL. In order to improve and optimize the performance of MQL, the orthogonal experimental method was adopted in this paper, and ANSYS Fluent software was used to carry out the computational fluid dynamics (CFD) simulation and the simulation data were statistically analyzed. The effects of six influencing factors (i.e. width of gas-phase narrow flow region, taper, output tube length, length of gas-phase narrow flow region, output aperture and pressure) on the performance of MQL were studied. The results showed that the primary and secondary order of the six influencing factors was different under different evaluation criteria. The most important parameter affecting the composite index was the absolute gas velocity at 0.1m away from the outlet. The optimal combination of the geometric parameters of the nozzle was output aperture of 2 mm, taper of 40 degrees, length of gas-phase narrow flow region of 1.5 mm, width of gas-phase narrow flow region of 0.3 mm, output tube length of 15.5 mm, and pressure of 5 bar.