Jet noise sources for chevron nozzles in under-expanded condition

Imperfectly expanded jet flows are known to have additional noise sources as Screech and broadband shock-associated noise. They generated by the interaction between instability waves that propagate from lip of nozzle shock cell structures. In this study, thorough experimental investigations were carried out on chevron nozzles assess importance parameters such count penetration angle pressure field emitted jet. Data acquired in state-of-the-art aeroacoustic facility at University Bristol. Acoustic measurements spectra, directivity overall sound levels along with near-field for Mach numbers ranging M = 1.1–1.4. Fourier-based Wavelet-based analyses used highlight different features various tested nozzles. Wavelet decomposition results presence chevrons reduce acoustic especially a higher axial distance increased reduction achieved deep angle.