An Investigation into Flow Field Interactions between Twin Supersonic Rectangular Jets

Abstract

View Video Presentation: https://doi.org/10.2514/6.2021-1291.vid Understanding interactions between jets in twin engine layout is vital for implementation of noise mitigation techniques. The current work investigates granular details of interactions between twin rectangular jets of aspect ratio 2:1 over a wide spectrum of operating conditions covering all flight regimes. Autocorrelation analysis on the far field data was used to associate the distinct characteristics of pressure signature to the different noise sources along with the identification of the strong directivity of screech harmonics through patterns unique to screeching jets. Wavelet analysis coupled with signal coherence analysis revealed the out of phase behaviour of twin jets at peak screeching conditions that led to tone attenuation & noise reduction. Classical (POD) & Spectral (SPOD) decomposition techniques were utilized to identify instability modes & their source location. The results showed weak screech – like behaviour of the underexpanded jet at NPR 2.5 and strong screech wave propagation at NPR 3.0 correlating to the peaks observed in the far field spectrum. Results from Large Eddy Simulations are used to compliment & verify the Schlieren results for screech conditions.