Fluid dynamics of the resonance tube

Abstract

Using a simplified wave-diagram and the gas-speed/sound-speed diagram, it is shown how the oscillations start and grow within a resonance tube. It is found that the oscillation amplitude tends to a limiting value which is obtained when the jet is fully swallowed by the tube during the phase of compression of the cycle. Experiments are carried out for jet Mach numbers from 0·1 up to 2. To achieve an adequate evacuation of the tube in the expansion phase, a thin cylindrical body must be used, which is laid along the axis of the jet to produce a wake and a correlative local deficiency of the kinetic energy of the jet. Measured amplitudes of pressure fluctuations are in good agreement with theoretical values.