Near-field shock/shear-layer interactions in a two-stream supersonic rectangular jet from three-stream engine

The three-dimensional interactions of the near-field structures in a developing two-stream exhaust by a threestream engine are documented. This paper analyzes six planes of near-field pressure generated by large-eddy simulation. After a basic documentation of the spectral analysis, several hot-spots that participate in the dynamics of the complex flow are identified. Cross-correlations between the hot-spots and the entire pressure fields reveal the interactions and propagations of near-field structures, which include shocks, vortex structures, and acoustic radiation. The near-field interactions are also studied in specific frequency bands, which enable us to map out their communication pathways.By applying phase-averagingtothe pressure fluctuations, strong phase relationshipsinthe developing jet are identified and the information propagation is confirmed by proper orthogonal decomposition. Some pressure signals outside the jet core are found as good reference for the phase of pressure fields and they are experimentally accessible as possible Kulite sensors. The different techniques applied show consistent results and confirm the identified regions and frequencies that play a key role in the near-field dynamics.