Aerodynamic and acoustic analysis of an optimized low Reynolds number rotor

The demand in Micro–Air Vehicles (MAV) is increasing as well as their potential missions. Either for discretion in military operations or noise pollution in civilian use, noise reduction of MAV is a goal to achieve. Aeroacoustic research has long been focusing on full scale rotorcraft. At MAV scales however, the hierarchization of the numerous sources of noise is not straightforward, as a consequence of the relatively low Reynolds number that ranges typically from 5 000 to 100 000. This knowledge however, is crucial for aeroacoustic optimization. This contribution briefly describes a low–cost, numerical methodology to achieve noise reduction by optimization of MAV rotor blade geometry. That methodology is applied to reduce noise from a MAV developed at ISAE–SUPAERO and a 8 dB(A) reduction on the acoustic power is found experimentally. The innovative rotor blade geometry allowing this noise reduction is then analyzed in detail using high–fidelity numerical approaches such as Unsteady Reynolds Averaged Navier–Stokes (URANS) simulation and Large Eddy Simulation using Lattice Boltzmann Method (LES–LBM). That strategy gives insight into the flow features around the optimized rotor and guidelines for the acoustic models used in a low–cost numerical optimization loo

Aerodynamic and acoustic analysis of an optimized low Reynolds number rotor

International audienceThe demand in Micro-Air Vehicles (MAV) is increasing as well as their potential missions. Either for discretion in military operations or noise pollution in civilian use, noise reduction of MAV is a goal to achieve. Aeroacoustic research has long been focusing on full scale rotorcrafts. At MAV scales however, the hierarchization of the numerous sources of noise is not straightforward, as a consequence of the relatively low Reynolds number that ranges typically from 5,000 to 100,000. is knowledge however, is crucial for aeroacoustic optimization. is contribution briefly describes a low-cost, numerical methodology to achieve noise reduction by optimization of MAV rotor blade geometry. That methodology is applied to reduce noise from a MAV developped at ISAE-Supaero and a 8 dB(A) reduction on the acoustic power is found experimentally. The innovative rotor blade geometry allowing this noise reduction is then analyzed in detail using high-fidelity numerical approaches such as Unsteady Reynolds Averaged Navier-Stokes (URANS) simulation and Very Large Eddy Simulation using La ice Boltzmann Method (VLES-LBM). at strategy gives insight into the flow features around the optimized rotor and guidelines for the acoustic models used in a low-cost numerical optimization loop