Study the Performance of Turbofan Engines under the Effect of Changing Chevron Nozzle Geometry

Abstract

In this study, the effect of changing the geometry of the chevron nozzleon the performance of turbofan engines is investigated. The study aims tocharacterize new chevron geometry configurations to investigate how toreduce the jet noise of turbofan engines while achieving minimal impacton engine thrust. To this end, a numerical analysis of the chevron nozzlewith different geometries will be performed. The model is validated andcompared with experimental and numerical data from the literature.Circular, elliptical, and triangular chevron cutout patterns with differentpenetration lengths are selected for the jet acoustic characterization ofchevron nozzles. These cutouts are applied to both the core nozzle andthe fan nozzle, resulting in a double chevron nozzle. The numericalstudy is performed using a steady 3D density-based k-ε turbulencemodel. The numerical results are compared with the base nozzle modelwith no cutout. It was found that best performing geometry in termsof minimizing noise level with gain in thrust compared to the basenozzle model was the circular-shaped Chevron with core diameter topenetration length ratio (penetration ratio) of 5 (DC 5). Furthermore, itwas also found that increasing the penetration length will increase thethrust gain of the engine.