Turbulent Vortex Shedding across Internal Structure in Thermoacoustic Oscillatory Flow

Abstract

A knowledge about vortex shedding frequency is important in order to understand the vortex shedding flow phenomena using the associated dimensionless parameter known as the Strouhal number. This paper presents the results of numerical simulations of vortex shedding processes at the end of a stack of parallel-plates, due to an oscillating flow induced by an acoustic standing wave (thermoacoustic case). The oscillating flow is simulated using Reynolds-averaged Navier-Stokes (RANS) turbulence models which are four-equation Transition SST and two-equation SST k-ω. Three drive ratios, DR (defined as the ratio of maximum pressure amplitude to the mean pressure) of 0.45%, 0.83% and 1.0% are investigated. The models were simulated at two flow frequencies which are 13.1 Hz and 23.1 Hz. The vortex shedding frequency was analysed after simulation reached a steady oscillatory flow condition. Two and four vortices flow phenomena were observed for both frequencies as drive ratio increased up to 1.0%. The Strouhal number has been obtained based on the vortex shedding frequency. The results show that vortex shedding pattern appears more stable at all the three drive ratios as the flow frequency increases.