Experimental investigation of dual jet flow past a heated surface: Effect of Reynolds number

Abstract

A dual jet flow comprises a wall jet, discharged immediately parallel to a solid boundary, flowing alongside a parallel jet whose exit is offset from the solid boundary by some distance. Despite the widespread industrial application of dual jet flows, experimental analysis of their flow and heat transfer characteristics is severely underrepresented in the published literature. As a result, the heat transfer capabilities and driving flow mechanisms associated with dual jet flows are not yet fully understood, meaning they cannot be optimised towards specific applications. The present study is thus concerned with characterising the transfer of heat to a dual jet flow for varying Reynolds number through experimental means. Using air as the working fluid, each jet Reynolds number is varied in the range 5500≤Re≤12,000 and the offset ratio and velocity ratio are each maintained at a constant value of 1. A constant heat flux generation of 1670W/m2 is maintained in the bounding wall and the surface Nusselt number distribution is measured using infrared thermography techniques. A distinct Nusselt number profile is observed with respect to downstream distance, which remains consistent regardless of the Reynolds number. The results indicate that increasing Re elevates the Nusselt number proportionally at all downstream locations, where the surface-averaged Nusselt number rises linearly with increasing jet Reynolds number.