In the process of small-hole machining in EDM

if the debris and bubbles are not removed from the gap flow field

which will seriously affect the processing efficiency and surface quality. By analyzing the characteristics of discharge gap

the geometric model of three-dimensional cylindrical gap flow field is established

the VOF

DPM model and the secondary development function of FLUENT were used to realize the continuous and random generation of debris and bubbles in the bottom machining gap

the simulation model of gas-liquid-solid three phase flow coupling of gap flow field in micro hole EDM was established

and adding hollow internal flushing liquid to remove debris

the distribution of debris and bubbles in the gap flow field was simulated and analyzed under different velocity and processing depth. Through the statistics of debris particle distribution

the results show that increasing the velocity of the internal flushing fluid can promote the remove of the debris and reduce the concentration of the bubble phase in the bottom gap and the side gap. The smaller the machining depth is

the greater the upward velocity of the bottom gap is

and the easier the debris and bubbles are removed.