Computational Study of Noise Reduction in CFM56-5B Using Core Nozzle Chevrons

Computational investigations of noise reduction in the CFM56-5B engine were carried out using optimal core nozzle chevron configurations. Two types of chevron designs were considered for the study, i.e. conventional triangular chevrons and rounded chevrons. Smooth edges instead of conventional pointed sharp edges were introduced in the rounded chevron design. Multiple chevron configurations were used for the analysis and noise reduction results of the two chevron types were compared with the noise generation values of the core nozzle (without chevrons). Both types of chevron design successfully reduced noise levels; however, the noise mitigation was more significant in the case of smooth-edged rounded chevrons which demonstrated noise reduction of more than 10% of the overall noise generated at the engine core nozzle. Smooth-edged rounded chevrons can be a good choice for the future noise reduction studies of CFM 56 engine series.