Research On Aeroacoustic Field And Flow About Subsonic Jet Based On Macro And Meso Methods

Jet aerodynamic noise is a matter of concern in both aeroacoustics and engineering field. Specially, impinging jet has a number of tissue engineering applications, which causes more and more attention. This research aims to study and analyze the jet aerodynamic sound behavior from both macroscopic to mesoscopic aspects. In this paper, experimental and numerical methods are combined to investigate the influence of different factors on impingement jet flow field, vortex quantity field and noise spectrum. The GKS computing platform is created to investigate jet flow under different rarefied gas condition.In order to study acoustic characteristics of jet impinging on the conical obstacle at low Mach number, the Large Eddy Simulation(LES) method is used for modeling impinging jet in different impinging distance. The noise characteristics and trend of impinging jet are experimentally and theoretically investigated, the model is proved to be correct by comparing with the experiment. Based on the formation, development and structure change of the vortex captured by simulation, the influence between impinging distance and far-field sound pressure and the relationship between vortex change and sound source distribution are investigated. It is found that impinging distance determines the dominant acoustic sources due to jet impingement. It is revealed from the numerical analysis that the acoustic level received at 10 De is the highest, dipole source due to vortex shedding is the dominant acoustic source; when jet is far to the obstacle, quadrupole source in the nature of low-frequency due to free jet is the dominant acoustic source.With virtual staggered grids and interpolation technique, two-dimensional argon gas free jet model is obtained with GKS(Gas-kinetic Scheme, GKS) method for far field boundary condition in subsonic speed. Mesh sensitivity is also discussed, medium density grid is selected for numerical simulation. The feasibility of GKS method is validated by comparing the simulation results of GKS method with results of other macro model, and the results of GKS method is better in the detail of the flow field. For five cases, namely that Kundsen numbers are 0.001, 0.01, 0.1, 1, 10 respectively, the Argon gas jet flow are simulated numerically, and different flow structures are investigated.