12th European Conference on Turbomachinery Fluid dynamics & Thermodynamics
A computational investigation of aerodynamic characteristics of model counter-rotating fan with BPR=20, developed in CIAM in the framework of European Project COBRA (Innovative Counter rotating fan system for high Bypass Ratio Aircraft engine), is presented in the work. Unsteady nature of the flow in counter-rotating fan has been studied including analysis of rotor-rotor interaction intensity and unsteady viscous wakes propagation through the axial gap and second rotor blade passages. The results of numerical investigation of the fan tone noise in approach operational conditions are also presented. The acoustic calculations were performed using in-house CIAM aeroacoustic code 3DAS. Directivity diagrams for the first 16 harmonics of tone noise in the forward hemisphere, obtained in the calculation, are shown. Comparison between these results and analogous results for model HBR counter-rotating fan with BPR=10 (designed in VITAL project) is performed. Additionally results were compared with experimental results for HBR fan.