Estimation of rotor aerodynamics using blade element theory

This paper presents a detailed analysis of the Blade Element Theory (BET) as applied to the aerodynamic performance of propellers and rotor systems. BET, a low-fidelity but widely used method, models the rotor blade as a series of independent elements along its span, allowing local aerodynamic forces to be calculated based on flow conditions. The approach combines the Blade Element Theory with Momentum Theory, implemented in a MATLAB program for a forward flight helicopter, facilitating the computation of thrust, torque and power coefficients. To account for inflow distribution and induced velocity effects, actuator disk theory is applied at the rotor disk level, providing a consistent estimation of the induced velocity required for accurate flow velocity values. The rotor solidity is used to compare lifting rotor system to an ideal actuator disk. Results demonstrate that the coupled method of BET and Momentum Theory provides accurate and consistent aerodynamic predictions for use in rotor design, optimization and validation against experimental measurements or CFD simulations.