Investigation On Mixing Enhancement And Noise Reduction Mechanism Of Chevron Nozzle

Chevron nozzle jet noise is a research hotpot in aeroacoustic andaerodynamic field. Chevron nozzle becomes the most popular technologyof passive noise control, when applied to aviation exhaust nozzle, for itsexcellent performance on noise control, thrust loss and simplemanufacturing.Experimental and numerical methods are combined to investigate theinfluence of different penetration and chevron counts on jet flow velocityfield, vortex quantity field, distribution of turbulence intensity andturbulent kinetic energy, noise spectrum, directivity. Using all thesemethods, the reason that chevron structure how to influence the flowstructure and further influence the acoustic field is explored. Main researchwork in this paper includes:1. Aeroacoustics experiment devices are built. Low speed noiseelimination wind tunnel and pneumatic noise elimination room are themain parts of the experiment devices, chevron penetration and numberare the main parameters for exploring chevron structure how toinfluence flow structure;2. The numerical computation study on both chevron nozzles and round nozzle is introduced and studied. Using structured grid and propercalculation settings, result of flow field, vortex quantity field anddistribution of turbulence intensity is obtained, which can be used forcomparison with experiment;3. The hot wire experiment on both chevron nozzles and round nozzle isintroduced and studied. Analysis on flow field, vortex quantity fieldand distribution of turbulence intensity is focused;4. Microphones are used to measure far-field noise and near-field noise ofchevron nozzles and round nozzle. Contour near-field sound pressurelevel, far-field noise spectrum and directivity distribution is obtained toanalyze the influence of chevron penetration and count number;5. Based on the result of flow field and acoustic field from the numericalsimulation and experiment, the relationship between the flow andacoustic field is explored.