Aeroacoustics of Twin Rectangular Jets Including Screech: Large-Eddy Simulations with Experimental Validation

High-fidelity large-eddy simulations (LESs) are performed to investigate aeroacoustic characteristics of jets issuing from twin rectangular nozzles with an aspect ratio 2:1 at two overexpanded conditions and the design condition. For all three jet simulated, LES predicts qualitatively similar near-field flow statistics those measured University Cincinnati. Using Ffowcs Williams-Hawkings method, captures fundamental screech tone its harmonics fairly well multiple observer locations in far-field. Intense flapping motions near field along minor axis, which influenced by jet-to-jet interactions, found correspond frequencies. Moreover, predicted overall sound pressure levels within 1–2 dB experimental measurements. However, tones appear be intermittent, as twin-jet interaction pattern varies irregularly. To extract dominant structures frequencies identify coupling modes, spectral proper orthogonal decomposition (SPOD) analysis is used. SPOD recovers energetic peaks frequencies, corresponding leading modes indicate strong upstream radiation originating fifth/sixth shock cells. conditions, show antisymmetric axis In contrast, behave symmetrically respect each other major line absence this direction. Furthermore, eigenvalues turn out be, least, orders magnitude larger than higher-order eigenvalues, suggesting potential reduced-order models for screech.