EXPERIMENTAL STUDY OF TURBULENT FLOW IN AN ANNULAR SECTOR DUCT

Abstract

The continuing interest in compact heat exchangers has created the need for studying the turbulent flows for different passage shapes. It has been recognized that generally circular tube results are not applicable to non-circular passages even when the hydraulic diameter (D,) is used as the characteristic dimension. Therefore, design data should be generated for each passage shape individually. The new flow passage shape under investigation in the present work is the annular sector duct which is a non circular passage. The major difference between the annular sector duct and non circular ducts of other geometries is that, the annular sector duct has both concave and convex boundaries. The combination of these combined boundaries would significantly affect the secondary flow pattern in the cross section area of the duct. In the present work, an annular sector duct of an acute angle of 60° and 0.5 diameter ratio, with an inner diameter of 102 mm and an outer diameter of 203 mm, is studied experimentally. The experimental test section was at a total length of 113D, The experimental work was carried out at two different 1eve1s. In the first level, the hydrodynamic characteristics of isothermal flow such as mean axial velocities and axial pressure gradient were measured. In the second level, the turbulence intensities of turbulent flow and turbulent shear stress were measured.