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Acoustic liners are widely used to suppress the acoustically driven combustion instabilities in jet engines. These are perforated cylindrical sheets traversed by bias flow and grazed by grazing flow through the orifices. These liners were primarily applied for cooling of the combustor wall. However, apart from cooling function, these are also well - known for having the ability to suppress thermo-acoustic instabilities by providing a substantial amount of acoustic dissipation. According to vortex-sound theory, damping of sound occurs by the transfer of acoustic energy to the kinetic energy of the jet of joint grazing-bias flow before being dissipated into heat. In this paper, time-domain numerical studies have been conducted to simulate the interaction between sound and joint grazing-bias flow. Effect of propagation of sound wave has been modelled by giving perturbation to the mean flow. For this purpose, sinusoidal perturbations of desired frequency were added to the mean flow by means of user-defined function (UDF). The UDF constitutes mean and perturbation components of the velocity. This approach has been well validated before further investigations in the present work. Turbulence models mainly standard k-ɛ, SST k-ɷ, and a relatively recent scale-adaptive simulation (SAS) model have been compared by assessing their ability to capture key flow features of these interactions. The Scale adaptive Simulation model adjusts itself to the already resolved scales in a dynamic way and allows the development of turbulent spectrum in the detached regions. Velocity power differences between the scenario of with and without perturbation were analyzed. Vortices were not found to be shedding for the unperturbed case. The velocity power difference spectra indicate a correlation between the amount of perturbation energy/acoustic energy loss and production of additional turbulence fluctuation components. The transport of recirculating zones was observed only for SAS model. The vorticity magnitude contours of overly diffusive character were observed for RANS model, while SAS model resolved the unsteady flow fields in the detached regions containing vortices quite well. The comparison of models makes it clear that for a transient numerical study of these interactions, SAS approach would give best results without any explicit requirement of extremely refined grids. The results of present work also supported the theory of vortex-sound interaction and the subsequent dissipation of sound.
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