A rotor blade aeroacoustics test platform at HKUST

This paper describes the design of the rotor blade aeroacoustics test platform at the Hong Kong University of Science and Technology (HKUST). The platform was constructed in an anechoic chamber with the dimensions of 3.3m (L) x 3.1m (W) x 2.0m (H). The test rig can assess the aerodynamic and aeroacoustic performance of small-scaled drone propellers. A two-dimensional traverse system is implemented for accurate controlling the relative positions of propellers to study the aeroacoustics of multi-rotors. A motor adaptor with a streamlined profile was made to reduce the resultant noise of unsteady flow. The test rig is covered with sound absorbing materials to minimize the noise reflection and scattering. The far-field noise radiation of propellers is measured at different observers using 20 GRAS 46BE microphones placed on the linear array. Systematic measurements are conducted to investigate the suitable time range for data acquisition due to the recirculation effect of the anechoic chamber. Generic propellers are developed to study the influential parameters for aerodynamics and aeroacoustics. The generic propellers were checked with both imbalance and machining accuracy before testing. The influence of sectional profiles, distribution of equivalent angle of attack and taper ratio on both tonal and broadband noise are measured.