Computational Aeroacoustic Prediction of Propeller Noise Using Grid-Based and Grid-Free CFD Methods

Two CFD codes are used to simulate noise data for a tandem cylinder experiment and two scaled NASA SR-2 propeller tests. The first code, STAR CCM+, is a grid-based commercial CFD code while the second code, SmartRotor, is an in-house grid-free CFD code which uses a panel method coupled with a discrete vortex method. Good comparison to experiment is achieved, with STAR CCM+ predicting the vortex shedding of the tandem cylinder case within 3 Hz and 10 dB while also predicting first propeller harmonics within 20 and 11 dB for the first and second propeller simulations, respectively. SmartRotor predicted first propeller harmonics within 6 and 37 dB for the first and second experiments, respectively. A parametic study on the influence of blade count on propeller noise was then performed using both codes to simulating the noise of 7-, 8-, and 10-bladed propellers finding quieter operation with increasing blade count.