Shinya Kusuda

Investigation of Fan Rotor Interaction With Pressure Disturbance Produced by Downstream Pylon

This paper presents an investigation of fan rotor interaction with potential pressure disturbances produced by a downstream pylon. Three-dimensional unsteady viscous analyses are performed for two fan rotor-stator-pylon configurations with different axial gaps between the stator and the pylon, and compared with the experimental results. To clarify the impact of the rotor-pylon interaction on the potential pressure flow field, a numerical analysis for the configuration in which a fan rotor is removed is also performed and compared with the numerical results with fan rotor. Actuator disk analyses are also performed to interpret the flow structures observed in the experiments and the numerical results. It is found that a fan rotor-stator interaction also exists in the fan flow field, and this may impact on the upstream propagating potential flow that dominates the unsteady forces acting on the rotor blades. A coupled analysis between fan rotor and stator is essential to accurately predict the unsteady blade force.Copyright

Behaviors of fan tone noise under the influence of circumferentially non-uniform steady pressure perturbation

The purpose of this study is to investigate the fan tone noise behavior under the influence of circumferentially non-uniform steady pressure perturbations caused by the engine pylon/bifurcation. The paper presents theoretical study with experimental and computational approaches on the noise of fan stages with and without a downstream cylinder which simulates the presence of the engine pylon/bifurcation, and further, describes comprehensive assessment of the fan tone noise behaviors. Firstly, model fan test results in an anechoic test facility for far-field noise and sound pressure spectra in the duct ahead of fan blades are presented to investigate the influences of the pressure perturbation. Secondly, the pressure fields ahead of blades obtained from three-dimensional unsteady CFD using UPACS are given for better understanding of phenomena affecting the fan tone noise. Finally, a new theory for fan noise prediction is developed to take into account the potential disturbance from the pylon, which interacts with the rotating rotor blades. Quantitative comparisons between the prediction and the experiment under different conditions of the pressure perturbation are presented.