Low-Fidelity Aerodynamic Load Analysis of Helicopter Rotor in Hover *

This paper presents a joint approach to numerical analyses of the Caradonna-Tung helicopter rotor with high-fidelity Computational Fluid Dynamics (CFD) and Blade Element Momentum (BEM) theory. The cross-section of the blade, i.e., the airfoil, was first numerically analyzed for a range angle of attacks (AoA) using Fluent, a computational fluid dynamics solver. This investigation generated the aerodynamic properties of the blade cross-section, such as pressure coefficient distribution, lift coefficient, drag coefficient, and the lift curve slope. These aerodynamic characteristics were then used to model the blade mathematically. This mathematical blade model was then implemented on a self-coded BEM solver. The rotor blade was analyzed on the BEM solver for various collective angles of attack with blade tip Mach numbers ranging from 0.1 to 0.8. The distribution of local thrust and torque coefficient along the span of the blade was investigated, along with the effect of the tip loss factor. The effect of compressibility on local thrust and torque coefficient distribution was also investigated. Furthermore, the blade thrust and torque coefficients were calculated for a range of AoA, allowing a comparison between the thrust and torque coefficients. Finally, the Figure of the Merit of the blade was calculated against a range of variables, including the thrust coefficient, angle of attack, and the blade tip Mach number. Based on these findings, an optimum operating condition of the rotor was proposed.