Noise source localization in Jets discharged by a Converging-Diverging Nozzle through NAH

Rocket and Modern aircraft Jet engines' discharge account for a significant amount of atmospheric noise and pose hazardous conditions for people in their vicinity. So, major amount of research work has been done and are still in progress to point out the regions of noise sources in a Jet which could be utilized to suppress the noise. In this work we carry out Patch and Scan based Planar Near-field Acoustic Holography on a jet emerging from a Converging-Diverging Nozzle using an Electret-Condenser Microphone array. Partial Field Decomposition technique has been employed, to stitch together the Holographic-plane data for different Scans, with a fixed phase relationship. Tikhonov Regularization has been applied to filter out high-frequency wave-numbers associated with noise in the data. The Holographic reconstructions have been carried out for various operating conditions / Mach numbers and the same is compared with that of a round jet (from an orifice) under similar conditions.