Physical simulation of melt flow in a mould in continuous casting steel slab was conducted by the digital particle image velocimetry （DPIV） system.Primary character of melt flow in the mould was described by analyzing the flow field.The effects of the submerged nozzle

immersion depth and drawing velocity on the flow field in the mould were investigated.The velocity vector

streamline and various equivalent cloud chart were calculated and analyzed by a commercial software TECPLOT to understand the flow change of liquid metal to control the flow and nozzle structure

improving the microstructure and properties of continuous casting steel slab.The results show that compared by nozzle with 15°

the tendency of flow-up of liquid metal at top of mould is more intense and impacting depth is lower for nozzle with 0°.With increase of submerging depth and decrease of flow velocity

inverse-flow range of up-moving of liquid metal is more broad

which results in the descending of eddy position.The liquid surface height should be controlled to be more than 100 mm.With the increase of drawing velocity

companying with increasing in flow velocity in the mould

surface-free becomes more and unstable

and impacting energy on narrow side is enhanced.