Measurements of Confined, Coaxial Jet Mixing With Pressure Gradient

Abstract

The mixing of a subsonic confined air jet with a coaxial secondary air stream is investigated experimentally. This work differs from previous studies in that emphasis is placed on the effects of an imposed adverse pressure gradient on mixing characteristics in the initial mixing (potential core) and transition regions. The results indicate that the presence of an adverse pressure gradient promotes more rapid mixing and spreading of the shear layer in the initial mixing region, as well as elevated turbulent normal stress and shear stress levels in the outer portion of the mixing layer after the primary and secondary streams have merged. Significant radial static pressure variations occur in both the initial mixing and transition regions as a result of turbulent normal stress gradients and streamline curvature effects induced by potential core entrainment.