Numerical Simulation And Control Of Cavity Flow

Cavity flow concerns many sophisticated phenomena, including shear layer instability, boundary layer separation, vortex motion and shock wave/boundary layer interaction, which is a key issue in fluid dynamics. In recent years, engineering has pay more and more attention to cavity flow applications, such as weapon bay, wheel well. Such researches contribute to the understarding of cavity flow mechanisms and the design of aircraft.In this thesis, we first investigate the applications of URANS and DES in the simulation of cavity flow. With regard to URANS, cell-central finite volumn method has been used. Roe flux difference splitting scheme is used for discretisation of convective fluxes, and solution reconstruction is applied for second-order spatial accuracy. S-A one-equation modelling is used for turbulence modelling. Five-stage Runge-Kutta explicit time-stepping scheme is used for temporal diescretisation and dual time-stepping is utilized for unsteady calculation. DES method resembles S-A modelling in wall region, but resembles LES in outer region. The results of these methods are analyzed and compared with experiment data. It can be found that DES method gives better accordance with experiment data, especially SPL comparison represents DES method can obtain a relatively accurate pressure fluctuations of cavity flow. Then the features of cavity flow in different Mach numbers and different length-to-depth ratio configurations are studied. It reveals that with Mach number increasing, Cp coefficient is increasing and in some case cavity type is altered. The cavity type will change from open to closed with length-to-depth ratio increasing. Finally slanted-back wall is adopted for passive control. It is shown that SPL is slightly reduced and the pressure fluctuation modes are altered.