The interactions between droplets have an important influence on the atomization of liquid fuel

the combustion efficiency

and the reduction of particulate matter emissions for an engine. For this reason

this paper presents results from an experimental study on the coalescence and break-up of droplets after collision. According to the shape and parameters of the droplets at different times after the collision of the droplets was captured by a high speed camera

analysis was done for the following effects of droplet collisions: the collision-coalescence motion for the collision between the droplets

the change history of the dimensionless length-to-width ratio of the oscillation motion

the critical size ratio of the breakup motion

and the liquid physical properties of the particles. The results show that the droplets collide and exhibit two forms of coalescence oscillation and break-up: for oscillating motion

at higher droplet collision velocities and dimensionless size ratios

there will be a larger dimensionless length-to-width ratio for the droplet oscillation; for the break-up motion

at higher collision velocities

there will be lower dimensionless size ratios

and lower liquid surface tension

shorter times over which the droplet breaks

and facilitated droplet break-up. The research results presented here can be used for atomization in engine cylinder

increasing the gas/liquid contact area and enhancing the combustion efficiency of gas/liquid heat transfer to improve the combustion efficiency of the engine.