Experimental Study of Flight Effect on Fan Noise : 1st Report, A Study of Inflow Control Device for Simulating In-flight Fan Noise in Static Test

Atmospheric turbulence and inflow distortion produced in static test cause the turbofan engine fan noise level difference between in-flight test and in static test. For the solution of this issue, inflow control devices were studied at NAL, which can simulate an in-flight fan noise in ground static test by means of the elimination of inflow distortion and turbulence drawn in by turbofan engines. Based on a lot of basic experimental data, a geodestic 4 m diameter semi-sphere inflow control device (ICD) for large turbofan engines was developed. From a series of tests on aerodynamic and acoustic characteristics of the ICD, it was made clear that the developed ICD is a device which functions effectively for simulating in-flight fan noise in ground static test.