Numerical Simulation Of Sound Propagation Based On High-order Discontinuous Galerkin Method

Since the advent of the first jet aircraft,the aircraft’s aerodynamic noise pollution has caused widespread concern in the community.The research of aerodynamic acoustics can be divided into three types,including theoretical analysis,experimental research and numerical simulation.because wind tunnel experiments can measure the noise distribution in space intuitively and effectively.They are widely used in airfoil noise control,cavity noise prediction,and the landing gear noise research.At the same time,due to the complex structure and the short start of the acoustic wind tunnel,there are few research resources about acoustic propagation in the open wind tunnel.The acoustic propagation characteristics of the open wind tunnel are still unclear.Based on the hybrid computational aeroacoustics method of "CFD+CAA",a high-precision noise propagation algorithm for complex background flow field is developed.The acoustic propagation characteristics of the real open wind tunnel are studied.In the noise propagation algorithm,a linearized Euler equation which can represent the non-uniform flow field information is used as the acoustic propagation control equation,The discrete algorithm uses the high-precision Galerkin method,and the boundary conditions adopt the non-reflective boundary condition.Firstly,the paper simulates the sound propagation process of monopole sound source in free space.Through the analysis of the results,the feasibility of high precision noise propagation algorithm is verified.Then the propagation process of the sound source in different shear flow fields is simulated.So the influence of the shear layer on the sound propagation characteristics is studied.After that,the paper carried out the numerical simulation of the acoustic propagation process of the sound source in the static open wind tunnel,the ideal uniform flow field and the real wind tunnel.The results show that the velocity of the spout,the shear layer and the wall of the wind tunnel all have effects on sound propagation of the open wind tunnel.There is a certain difference between the sound propagation of the real wind tunnel and the ideal condition.