An experimental investigation of the shrouded centrifugal backswept impeller flow field has been conducted at off-design flow using Laser Doppler Velocimeter (LDV) and shaft encoder.Measurements of the three-dimensional velocity field at flow rates greater and smaller than design value were acquired.The measurements describe both the throughflow and secondary velocity field along several main planes through the passage.The velocity vector profile clearly documents the different positions

intensity and development of the separation flow when changing the inlet flow rates.The secondary velocity vector plots show that the migration of the secondary vortex across the main flow was influenced by flow rates which made the centrifugal and Coriolis force changing.