Aeroacoustic Fields of Supersonic Twin Jets at the Ideally Expanded Condition

Abstract

The aeroacoustic fi elds of twin jets and the equivalent single jet were experimentally investigated using particle image velocimetry (PIV), schlieren visualization, and acoustic measurement. The present study focuses on the aeroacoustic fi elds of the twin jets, and the e ff ect of the interaction between each jet was investigated using various nozzle spacing. The PIV results indicated that strong interaction causes elliptical jet growth on a cross-stream plane and a decrease in the Reynolds stress of the inner shear layer on a plane containing both jet axes. The dynamic mode decomposition of the double-pulsed schlieren images extracted the interaction of each jet, which relates to the Mach wave generation. The noise of the twin jets was basically quieter than the noise of an equivalent single jet because of a shielding e ff ect and a reduction in the Reynolds stress resulting in a decrease in the overall sound pressure level.