LBM 해석을 이용한 천음속 충격파 및 고속 충격 소음 예측 연구

초록

With the increasing demand for high-speed operation of next-generation rotorcraft, transonic flow phenomena and the associated high-speed impulsive (HSI) noise generated by rotor blades have attracted attention. Under high-speed operating conditions, locally transonic flow develops on the advancing side of the rotor blade, leading to the formation of strong shock waves on the blade surface. These shock waves degrade aerodynamic performance and act as the dominant source of HSI noise affecting the far-field acoustic environment. Although the importance of transonic shock-induced noise has been widely recognized, reliable verification of high-fidelity numerical approaches remains essential. In this study, Lattice Boltzmann Method (LBM) coupled with a Ffowcs Williams–Hawkings (FW-H) acoustic formulation based on permeable surface is applied to analyze transonic shock structures and HSI noise characteristics of rotor systems. To assess the capability of the numerical framework, transonic flow simulations are first conducted for the two-dimensional RAE 2822 airfoil and the three-dimensional ONERA M6 wing. The results show that the LBM simulations accurately predict shock locations and pressure recovery characteristics, exhibiting good agreement with experimental pressure coefficient distributions in both two- and three-dimensional transonic benchmark cases. The validated approach is extended to a 1/7-scale UH-1H helicopter rotor under hovering conditions to investigate the effects of tip Mach number on shock formation and HSI noise generation. The simulations capture the development of spiral shock structures on the rotor disk, which become more pronounced as the tip Mach number increases. Far-field acoustic predictions obtained using the permeable FW-H formulation successfully predict the variation of HSI noise with tip Mach number and show a good agreement with experimental measurements. Overall, the present study confirms that the LBM combined with permeable FW-H approach is a physically reliable framework for predicting transonic shock structures and HSI noise of rotorcraft.

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