Pipe flow is a classic hydrodynamic issue.Most pipelines contain bends,and bends cause energy loss and distort the flow because of secondary flow.Deflectors are often used to adjust the flow quality in a bend.In this study,a numerical simulation using ANSYS Fluent 19.0 is used to analyze the effects of the deflector number,location and angle on the flow characteristics of a square pipe with a 90° bend.The velocity non-uniformity and the head loss are analyzed quantitatively.The secondary flow is presented visually,and its evolution characteristics are assessed.An optimized installation scheme for the deflectors is discussed,and a reference is provided for controlling the flow quality in bends via deflectors.