Effect of chevron count and penetration on the acoustic characteristics of chevron nozzles

摘要: Experimental investigations have been carried out on chevron nozzles to assess the importance of parameters such as number chevrons (chevron count) and penetration. Acoustic measurements overall sound pressure level, spectra, directivity, acoustic power, broadband shock noise made over a range nozzle ratio from sub-critical underexpansion levels. Shadowgraph images shock-cell structure jets various also captured for different ratios. The results indicate that higher count with lower level penetration yields maximum suppression low medium Of all geometries studied, eight lobes 0° angle gives reduction. Chevron are found be free screech unlike regular nozzles. power index has calculated quantitatively evaluate performance is pertinent parameter reduction at ratios, whereas high crucial. illustrate by careful selection substantial can achieved.