The results of 700-mm fan model study in terms of acoustic response obtained at the CIAM C-3A test rig anechoic chamber are represented. The fan model is a bypass universal propulsion simulator UPS (bypass ratio 8.5, pressure ratio 1.54, fan tip speed 395 m/s, scaled factor k = 2.7) with one-stage fan and nacelle inside which hush kit may be installed.

At the CIAM test rig C-3A acoustic investigation of the S-2 wide chord fan model was carried out. The results showed that at Runway and Flyover the S-2 fan model noise spectra practically did not differ from the noise spectra of single stage fan models with conventional blades.

At Approach mode the S-2 fan model noise spectra radiated in front hemisphere contains several high level tonal components which could be identified as tonal noise at sum frequencies of rotor interaction with the first booster stage. It should be mentioned, that at Approach mode tonal noise at BPF practically does not exceed the broadband noise.

The UPS noise matrices obtained allowed noise prediction of the hypothetical aircraft equipped with turbofan, the scaled fan model of which was tested.

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