Predicting supersonic jet mode-switching using non-negative matrix factorization

• DOI: 10.1121/10.0008040
• Publication Date: 2021-11-18T22:08:38Z
• Authors: Aprameya Satish; Aharon Karon; Alessio Medda
• Keywords: Flapping; Jet engine; Mode (computer interface)

Imperfectly expanded supersonic jets contain a shock-cell structure in the jet plume which plays role generating screech tones along with other noise sources. Depending on Mach number of jet, two types motion or “jet modes”—a toroidal mode and flapping may occur, resulting generation different that are not harmonics each other. At given condition, these modes (and corresponding tones) can switch between based environmental conditions seemingly non-deterministic manner. Understanding when mode-switching occurs at fine time resolution provide better understanding sensitivity dynamics. This work presents preliminary results novel method predicts particular tone is active using non-negative matrix factorization. Using this technique, spectrograms decomposed into set basis vectors to present activation functions indicate dominant. An function comparison technique then used identify activations mode-switching.