Aerodynamic noise prediction for long-span bodies

A prediction method for aerodynamic noise from long-span bodies is proposed. The present method is based on the hybrid method, and consists of (i) incompressible large eddy simulation (LES), (ii) linearized perturbed compressible equations (LPCE) for 2D acoustic field at spanwise wave number, k_z=0, (iii) 2D Kirchhoff method, Oberai's 3D-correction for spectral acoustic pressure at the far-field, and (iv) estimation of the far-field SPL for a long-span body with considering spanwise coherence function. In the present study, accuracy of the hybrid methods is assessed by considering turbulent flow noise problems for a fundamental aerodynamic body with long span. The nose from a circular cylinder with 30D span at Re_D=4.6×10⁴ and M=0.21 is predicted with the present methodology. Aerodynamic and aeroacoustic results are compared with the experimental data. Also, fundamental issues on computations of acoustic field, and estimation methods for SPL will be discussed in conjunction with the proper flow physics.