On Predicting the Frequency of a Flip-Flop Jet Nozzle

This research deals with the oscillation frequency of a classical and simple flip-flop jet nozzle with one feed-back loop based on the measurements of pressure and velocity. From these measurements, the traces of pressure difference between both ends of a connecting tube are modeled by a triangular wave, and the flow velocities in the connecting tube are calculated numerically. The resulting accumulated flow work, which consists of the time integral of mass flux into the re-circulation region on the low pressure side wall from the re-circulation region on the opposite high-pressure side wall through the connecting tube, is more adequate to determine jet-oscillation frequency than any other time integrals. This includes those of momentum flux and kinetic-energy flux. It is confirmed that jet-oscillation frequency predicted on the basis of this accumulated flow work agrees well with experiment.