一种基于平均流场的翼型尾缘宽频噪声预测方法

发展了一种基于平均流场的翼型尾缘宽频噪声预测方法.可压缩Navier-Stokes方程被重组为能描述气动噪声产生和传播的形式,包括准确描述声传播的线性算子和雷诺应力构成的声源项.为减少计算时间和避免格林函数空间奇异性,采用伴随格林函数方法求解格林函数;同时采用基于平均流场的声源模化方法生成声源项.为了验证该方法,预测了NACA0012翼型尾缘宽频噪声,其中平均流场使用OpenFOAM计算,格林函数采用均匀流动下半无限大平板近似.预测结果表明:对于不同来流速度和攻角,该方法不仅能准确预测噪声幅值及峰值频率,而且噪声频谱也都在实验结果的误差范围之内(±3dB),证明了该预测方法的精度和适用性. 

A RANS-based prediction method for the airfoil broadband trailing edge noise

A RANS (Reynolds averaged Navier-Stokes)-based prediction method for the airfoil turbulent boundary layer trailing edge noise was developed. The Navier-Stokes equations were firstly reformulated to the form that the left hand side was a linear wave propagation operator and the right hand side was the source term that consists of Reynolds stresses. To reduce the computation time and avoid the spatial singularity of the Green function, the adjoint Green functions method was employed to compute the exact or ‘tailored’ Green functions; moreover, the source term was generated by the RANS-based modeling method. Application of the present method on the broadband trailing edge noise of NACA0012 airfoil was made to validate the present method. The OpenFOAM solver was applied into the mean flow computation of NACA0012 airfoil and the Green function for semi-infinite flat plate under uniform mean flow was used to approximate that of thin airfoil. The predicted spectrum of the broadband trailing edge noise indicates that: for various incoming flow velocity and angle of attack, the current method can not only predict the amplitude and the peak frequency accurately, but also the whole spectra is in good agreement with the current available experiment data (±3dB), which demonstrates the accuracy and applicability of the method.