Adaptive BEM for low noise propeller design

A potential-based Boundary Element Method is presented for the aerodynamic and acoustic design of propellers at on- and off-design point conditions. Using an adaptive method, a family of airfoil sections is selected to produce the required performance (thrust, torque and efficiency versus advance ratio) at different cruise flight levels. Climb conditions are also considered in order to check the off-design point performance. Once the available airfoil data have been stored in a database, the code processes the families of airfoils to generate a complete geometry for a propeller of the specified performance with an optimized noise emission. The computational scheme adjusts the blade geometry (radial distribution of chord, local sweep angle and thickness) under the control of an optimization routine. The geometric data and pressure distribution are then used in the acoustic calculation, based on the Ffowcs Williams-Hawkings equation. Results are presented demonstrating the application of the technique and the resulting aerodynamic performance and noise output.