EXPERIMENTAL STUDY OF 3-D TURBULENT FLOW FIELD IN A 90° BEND PIPE

The 3 D turbulent flow field in a 90° strongly curved pipe (D=280mm,R_c/D=0.87) has been experimentally studied under different Reynolds numbers (Re=2.78×10.5～5.40×10.5) with a single slant hot wire measurement system and a five hole dynamic probe.The detailed experimental results are given,including the distributions of 3 D time averaged velocities,turbulent energy,total pressure and static pressure along the curvature direction at five different cross section.It is shown that the loss in this strongly curved pipe mainly occurs near the inner side wall,and increases rapidly near the 90° cross section due to flow separation.Static pressure distribution near the outer side wall is higher than that near the inner side wall throughout.The flow near the inner side wall accelerates from the 90° to the 30° cross section and decelerates after 30° cross section.But near the outer side wall,the tendency becomes adverse,and the pressure gradient here is much smaller than that near the inner side wall.