基于LBM-LES方法的翼型气动噪声直接数值计算

Direct numerical simulation of airfoil aeroacoustic based on LBM-LES method

直接数值计算方法对航空飞行器机体气动噪声产生机理研究及噪声预测非常关键。本文基于在格子玻尔兹曼方法(LatticeBoltzmannMethod,LBM)框架下的大涡模拟方法(LargeEddy Simulation, LES)对SD-7003仿生翼型在较低马赫数条件下的气动噪声进行了直接数值计算,雷诺数选取为8.0×10~5。LBM方法采用多松弛时间近似,格子离散速度模型为D2Q9模型,LES方法的亚格子模型是动态Smagorinsky模型。噪声直接计算结果表明:LBM-LES方法能较精确地预测低马赫数及中低雷诺数条件下翼型气动噪声远场的声压,与实验结果相比,误差在10%以内;同时可以直接得到噪声声场及传播过程,并能揭示噪声的生成机理。

The direct numerical simulation of airfoil acoustic is key to understand and predict the airframe noise for various aircraft.The simulations are performed for the SD-700 airfoil at Reynolds number 8.0×105 and low Mach number,based on Large Eddy Simulation(LES)in the frame of Lattice Boltzmann Method(LBM).The Multi-Relaxation Time(MRT)and D2Q9 discrete velocities model are used for LBM,and dynamic Smagorinsky-subgrid model for LES.The numerical results for flow and farfield noise show good agreement with the experiment.The LBM-LES method can accurately predict the farfield sound pressure of airfoil at low Mach number within 10%relative error compared with experimental data,moderate or low Reynolds numbers.The sound field and its propagation can be obtained directly,the mechanism of noise production is revealed.