Experimental study on nonuniform Hartmann resonators

Spectral features of cylindrical and conical Hartmann resonators are compared in this work. Experiments have been conducted at different nozzle pressure ratios at a fixed stand-off distance. Resonance frequencies of conical cavities are found to be higher than those of cylindrical cavities of the same length. Spectra, also shows higher resonant modes excited along with the fundamental. Some qualitative differences were observed between spectra of cylindrical and conical resonator. The directivity is always maximum in the downstream direction for both cavities. These devices are capable of producing high amplitude tones, over a wide range of frequencies.