Aerodynamic noise of the rod-airfoil computed by using acoustic analogy

The most traditional methods about computation of the noise are half-experience. This paper is used acoustic analogy which is in combine with computational fluid dynamics. The approach is achieved by two step procedure. In the first step, the unsteady flow field is computed in a near-field domain comprising all acoustic sources via a URANS solver. In the second step, the FW-H integration approach with a permeable data surface is used to extend the dynamic near-field to the acoustic far-field. Compared with the traditional half-experience method, this approach only has small amount of calculation, and accurate result can be obtained. The most important, it can compute nonlinear noise and be used easily. This paper calculates the noise of the rod-airfoil by the use of aeroacoustics integral formulation, employing Gauss integral formula and constructing discrete scheme in time. In the time domain and frequency domain, this paper calculates respectively the acoustic pressure changes and sound pressure level changes over time steps in the observation. The result agrees well with the experiment data. Furthermore, the paper researches the effect of airfoil wake flow on precision.