Nozzle geometry effects on supersonic jet interaction

Abstract

The coupled interaction of jets from two nominally identical convergent/divergent nozzles is examined as a function of nozzle spacing. The screech modes of two coupled jets correspond to those observed from single plumes, but the modal amplitudes are strongly dependent on nozzle spacing. For closely spaced nozzles, coupling occurs at low jet Mach numbers and is suppressed at high Mach numbers. The converse is true for large spacing. The amplitude of the coupled jets is independent of the nozzle design Mach number, unlike the screech amplitudes of isolated plumes that decrease near the design point. Interference between the plumes and the relative phasing of the acoustic sources are proposed as mechanisms for the geometry dependence of the jet coupling.