The Use of Streamwise Vorticity to Increase Mass Entrainment in a Cylindrical Ejector

Abstract The following work documents the effect of streamwise vortices generated at the nozzle exit of an axisymmetric air jet on the amount of mass entrained into an ejector. In an experimental analysis of the mass entrainment of circular jet ejectors, we found that the introduction of half delta wing vortex generators in the exit of the jet nozzle (Reynolds number of 50,000) increased the amount of entrained mass by as much as 35% over the amount of increase provided by the ejector alone. The effectiveness of the generators was studied for several cases varying spacing, diameter, length, and Reynolds number. Although the performance of an ejector is a strong function of these parameters, the mass entrainment increased in all cases studied due to the presence of the vortex generators. Nomenclature Ae ejector area Aj jet area De ejector diameter Dj jet diameter Le ejector length ̇ m mass flow rate ̇ m ejector mass exiting the ejector ̇ m entrained mass entrained into the ejector ̇ m nozzle mass exiting the jet nozzle Re Reynolds number ref reference case S distance from jet to ejector vor vortex case U time averaged velocity