<p>A turbulence inhibitor is a key flow control component in a tundish, yet relatively little numerical simulation research has been conducted on turbulence inhibitors during the opening stage. In this study, turbulence inhibitors were precisely redesigned, and the structural stiffness of the turbulence inhibitors increased. The thermal stress of turbulence inhibitors during the open stage in a tundish was investigated. The flow field of the tundish during the open stage was simulated with a volume of fluid(VOF) model, and a fluid-thermal-stress coupling model was used for thermal stress analysis of the turbulence inhibitor during the open stage. Water model experiments were also conducted. According to the model simulation, the sequence of the temperature increase in the innovative internal rotation turbulence inhibitor(IIR TI) during the open stage was highly consistent with the flow path of the molten steel. The flow path of the molten steel started from the bottom center of the IIR TI → the side of the bottom→ the lower part of the wall → the upper part of the wall → the eaves, whereas the sequence of the temperature increase was from the bottom center → the side of the bottom → the lower part of the wall → the upper part of the wall → the inner wall of the eaves → the outer wall of the eaves. The sequence of the temperature increase in the IIR TI during the open stage was from the bottom to the top and from the inside to the outside. The guiding hole was a weak structural area that became a stress concentration area. The reinforcing bar effectively reduced the stress at the guiding hole of the IIR TI. As the diameter of the reinforcing rib increased, the maximum stress of the IIR TI continuously decreased.</p>