Flow visualization of the transient effect of the internal two-phase flow on the external iso-pentane flashing spray under different injection pressure

•Internal flow and iso-pentane spray of different injection pressure were visualized.•A shattering index is put forward to dominate the spray pattern conversion.•A correlation between the spray cone angle and the shattering index is proposed.•High-void-fraction internal flow raises spray cone angle and droplet concentration.•Lower shattering index yields slower change but larger increase of radial expansion.