An experimental study of AS350B2 helicopter noise

In a cooperative research program of helicopter noise between Chinese Aeronautic Establishment and German Aerospace Center, one Aerospatiale AS350B2 helicopter was chosen to take noise measurement flight tests at Pinfan airport, Harbin, China. This paper presents the test design, instrumentation set-up and the test results for all of 10 operating conditions. Some of the test data are studied based on the Fourier transform and the wavelet transform. The experimental results show: (1) the high sound exposure lever appears in take-off and approach conditions, (2) the impulsive noise mainly originates from the tail rotor in take-off flights and from the main rotor in approaches, (3) when the helicopter flights at mid-speed and about 6° approaches, the serious blade vortex interaction happens and its noise directs towards the rotor advance sides.