오픈로터 소음 저감을 위한 비정상 유동 하의 강건최적설계

Robust design optimization for open rotor has been conducted. To alleviate computational burden of robust measurement in the design, Kriging surrogate model was employed to model responses. For performance evaluations of open rotor especially, unsteady flow simulation by state-of-the-art CFD technique of harmonic balance method was used, and it coupled with aeroacoustic analysis based on acoustic analogy. Thanks to the combined analysis between aerodynamic and aeroacoustic analyses, unsteady noise characteristics of the open rotor was efficiently investigated. The baseline configuration is 8×8 pusher-type of DLR CROR system, and rated condition is a cruise regime. Two types of aleatory uncertainties were modeled by probability density functions, and reflected in design variables and free-stream Mach number. The result showed that about 3dB of noise reduction was achieved, with it maintained thrust level of the baseline rotor system. Moreover, the validation of robustness for the uncertainties was performed, and showed the robust optimum rotor was more insensitive to the uncertainties than the baseline open rotor.