A numerical investigation of the aerodynamic noise generation mechanism in transonic cavity flows

An overview of the progress of research work on the aerodyamics and aeroacoustics of three-dimensional cavities at transonic speeds is presented with special attention to identify the flow structures responsible for resonant tones. The cavity length to depth (L=D) ratio values were chosen to focus the investigations mainly in the open cavity flow regime. The cavity geometries considered also included the cavities with stores. In the first part of this project, a two-step computational solver which involves the solution of the Navier-Stokes equations in the first step, and an integral surface solution of the Ffowcs-Williams and Hawkings equation in the subsequent step, is developed especially for the accurate capturing of aeroacoustic phenomena. The solver developed is validated using a wide range of test cases and it also used to study an empty cavity unsteady flow problem at transonic speed. In addition, the solver was tested for its robustness by computing flow around an isolated landing gear. In the second part of the thesis, a general purpose CFD solver was used to tackle complex geometry problems which included cavities with missiles and spoilers. The flow field within the cavities investigated is shown to be dominated by highly unsteady periodic phenomena. The oscillation mechanism and the internal flow structures are found to remain largely unaected by the presence of stores, however, the spanwise variation on the flow is limited.