Dynamics of a plane pulsed jet

Pulsed jets are now extensively used in a wide variety of engineering devices for advanced aerodynamic applications, namely drag and lift control, heat transfer, vortex generation, noise reduction and mixing. Despite their efficacious use in so many applications, a clear understanding of the fundamental physics of an isolated pulsed jet has not been addressed yet. A plane pulsed free jet in the Reynolds number range of 50 – 500, and Strouhal number range of 0.01-0.5 was studied with DNS. Various lip configurations were changed in the nozzle to produce different vortical structures. With a zero net inflow mass flux, the pulsed jet, generates a downstream mean momentum flux which is extremely sensitive to the inflow conditions and nozzle geometry. Interestingly, with a constant Reynolds number, increasing the Strouhal number enhances the entrainment rate, presumably due to vortex pairing occurring closer to the inlet. Additionally, the mean momentum flux shows to increase downstream. We are addressing critical questions that will help to explain complex 3D configurations (e.g. synthetic jets) and their applications in flow control.