Investigation of Cavity Flow Aerodynamics Using Computational Fluid Dynamics

The acoustic environment of a bomb bay or cavity causes large pressure oscillations and the severity of them is a problem that has intrigued researchers for years [68]. Many suppression techniques have been applied with varying degrees of success. Despite this, the understanding of why the pressure oscillations exist or how the suppression methods work have not been investigated as thoroughly. Advances in CFD permits modelling of the cavity environment to be performed and to reveal details about the flow which is difficult to obtain from experiments. The contribution of this thesis is to investigate the flow physics for cavity flows and use the CFD results synergistically with experimental and theroretical information to enhance the understanding of the problem. The realism of the computational aerodynamics method is substantially validated before any investigation of the flow features is performed, which is the motivation of this work. The verification of the approach is discussed with regards to the problem of grid discretisation for cavity flows. The approach is validated against experimental data for open, transitional-open, transtional-closed, and closed cavity flow from Mach 0.6 to Mach 1.35. For open cavity flow pressure traces taken on the floor of the cavity agree well with those obtained from experiment. Other characteristics of the flow agree well with experimental data and the validation instils confidence that the flow physics simulated. Open cavity flow is that of most interest to researchers. The flow is typical to that found to exist in the bomb bay of the F-111 and is characterised by intense acoustic levels. A review of the work of previous experimental researchers is included for comparison with the findings of the present thesis. The flow physics indicate that