Abstract
In this paper, optimization of blade twist distribution to maximize the performance of a rotor during hovering flight is described. The Japan Aerospace Exploration Agency has been developing a hybrid method coupled with computational fluid dynamics (CFD) and a prescribed wake model to reduce the computational cost. In this study, as a first step for the application of this method to optimize the blade configuration, the influence of the blade twist distribution variation on the figure of merit is investigated. The Hover Tip Vortex Structure Test (HOTIS) experiment is used as a calculation model, and the tip Mach number is 0.641. It is found that the result of using the hybrid method for the baseline blade configuration corresponds well with the full CFD of the rotor performance and figure of merit. For the influence of the blade twist on the figure of merit, high figures of merit are obtained when the difference of the blade twist at r/R=0.875 from the baseline Δθ1 is around 1–3 deg and the difference of the blade twist at r/R = 1.0 from the baseline Δθ2 is of negative value. Particularly, in the case of Δθ1 = 2.0 and Δθ2 = −3.7 deg, a maximum value of figure of merit of about 1.5% higher than the baseline design is achieved.
