In order to simplify the grid generation during aerodynamic noise prediction

the computational aeroacoustic (CAA) method and immersed boundary method (IBM) were combined together to solve the adjoint Green's function. According to the basic formulation of adjoint Green's function

a special case of cylindrical acoustic scattering problem was designed. The comparison between the numerical results and the analytical solutions prove that the numerical methods used are reliable and feasible for the calculation of adjoint Green's function for problems with complex geometries. Finally

the combined numerical methods were used to solve the adjoint Green's function of the jet flow from a nozzle with chevron and pylon interaction. Result shows that

because of the scattering effect caused by jet flow shear layer

the distribution of adjoint Green's function in jet flow is uneven

and the maximum value is 3 times higher than the minimum value. This simulation results reveal the relative importance of different regions with the same sound intensity to the far field noise. Therefore

low noise nozzle design can focus on reducing the sound intensity in the larger area of Green's function.