Simulation of powered resonance tubes: Helmholtz resonator geometries

PRT actuators, which consist of a high pressure air supply jet, a resonance tube, and an integration slot, are capable of producing high amplitude pressure oscillations. The traditional approach requires a very long resonance tube when low frequencies are desired. A Helmholtz based PRT offers a method of substantially reducing the resonance tube length requirement. This paper is focused on present simulation results for such a design with comparisons to theory and experiment. At low NPR values a Helmholtz response in simulations and experiments shows good correspondence with theory. At higher values of NPR the computational and experimental comparisons to theory suggest that non-linear effects must be considered and that screech in particular can suppress or shift the Helmholtz response. The effort to integrate simulations, theory, and experiment has been fruitful. There is general agreement between these three methods in terms of the frequency, amplitude, and directivity of the actuator output field, to the extent that they have been examined.