Axial vortex forms on pipe wall while fluid flows onto flute, so strengthening disturbance of boundary layer and destroying laminar layer to promote heat transfer through boundary layer.

• 当旋涡快要消失时流体又经过下一个凹槽处,这样就能使旋涡不断的产生、不断的消失,保持了连续而稳定的强化作用。