Experimental and computational visualization and frequency measurements of the jet oscillation inside a fluidic oscillator

The jet oscillation inside a fluidic oscillator is investigated in detail in order to obtain more information about the physical mechanisms that drive the jet oscillation. Particle Image Velocimetry measurements are conducted inside the oscillation chamber of the fluidic oscillator in order to visualize and measure the frequency of the jet oscillation. A transparent afterbody allowed laser illumination of the oscillation chamber. The experiments are conducted for a low jet exit Reynolds number of 321, based on the maximum velocity and the nozzle width at the jet exit plane. Computational simulations of the flow field inside the oscillation chamber are obtained by solving two-dimensional, incompressible and unsteady Navier-Stokes equations for the same throat Reynolds number and using a finite element methodology. The flow field is assumed to be laminar and constant viscosity. The jet oscillation frequency obtained from the computational simulations is underpredicted but still in close agreement with the measured PIV frequency. The computational simulations also revealed the formation of a pressure gradient across the jet as it is deflected from the symmetry position. This is one of the main driving mechanisms of the jet oscillation. The variation of the jet oscillation frequency with throat Reynolds number is also determined by single sensor hot-wire measurements inside the oscillation chamber.