Control of Jet Noise Through Mixing Enhancement

摘要: The idea of using mixing enhancement to reduce jet noise is not new. Lobed mixers have been around since shortly after became a problem. However, these designs were often post-design fix that rarely was worth its weight and thrust loss from system perspective. Recent advances in CFD some inspired concepts involving chevrons shown how can be successfully employed reduction by subtle manipulation the nozzle geometry. At NASA Glenn Research Center, this recent success has provided an opportunity explore our paradigms understanding, prediction, reduction. turbulence measurement technology for hot jets also greatly aided ability cause effect relationships geometry, plume turbulence, acoustic far field. By studying flow sound fields with various degrees subsequent manipulation, we are able intuition regarding make noise, test prediction codes, pursue advanced concepts. paper will cover existing as they relate reduction, present experimental analytical observations support paradigms.