Eulerian–Lagrangian–Eulerian Simulations of Two-Phase Minimum Quantity Lubrication Flow in Internal Drill Bit Channels

Abstract

The goal of reducing oil consumption for lubrication of machining processes can be achieved by means of minimum quantity lubrication (MQL). In minimum quantity lubrication, the cutting fluid is a mixture of air and oil where only a small amount of the latter is added to the mixture. However, this reduced oil consumption must not be detrimental to the effectiveness of the machining process. In order to analyze the performance of minimum quantity lubrication, the two-phase fluid dynamics of the MQL dispersion fluid has to be investigated. In the present work, this two-phase flow for internal lubrication of a drilling process was studied by means of numerical modeling and simulation based on an Eulerian–Lagrangian–Eulerian (ELE) model. The Eulerian–Lagrangian–Eulerian model can properly describe the transition between the aerosol and wall liquid film two-phase flow. Attention was focused on the flow in the internal channels of a twist drill. A parametric study was carried out in order to disclose the effects of three different relevant parameters, namely the oil droplet diameter and the mass flow rate at the channel inlet and the drill bit rotational speed, on the MQL cutting fluid flow quality inside the drill bit channel and at the channel outlet.