Characteristics and control of flow in a curved duct

The study of fluid flow through curved ducts assumesimportance in thE field of heat exchangers and air conditi-oning systems, as well as in a wide range of technologicalapplications in modern industry. The present work sets outto investigate the characteristics and means of controllingflow configuration in the duct exit section.This study was carried out on a 90- degree bend ofsquare cross section and unity area ratio. The radius ratioof this test duct was 1:4.33 (=inner radius/outer radius),the flow discharge value (a> is constant and equal to 1.42mJ/sec.The test duct was mounted at exit of a specially con-structed wind tunnel rig provided with suitable instrume-ntation. Measurements were made at different sections of theduct including sections before and after the curved zone. Ateach section quantities such as static pressure, total pres-sure and flow velocity were recorded.To control the flow in the exit region, three arrange-ments were attempted. These were:(i) A cascade of guide blades fixed inside the curvedregion.