Numerical study of the influence of bichannel-system geometry on the existence domain of Hartmann effect

The present numerical study is aimed at revealing the influence of the nozzle exit-to-resonator edge distance on the gas-dynamic characteristics of the acoustic-convective flow in the flow path of a bichannel system. The aim of the work is the development of a computational technology for describing physical processes in the duct of multichannel systems that generate high-intensity acoustic fields. Five configurations of the bichannel system in which the gap between the nozzle exit and the resonator edge was 0.85, 1.10, 1.35, 1.60, and 1.85 of the resonator diameter, were analyzed. As a result of the study, a complete picture of the gas-dynamic flow formed in the duct of the bichannel system was obtained, including the resonating cavity and the region in between the nozzle and resonator. With the help of numerical simulation, the formation of a flow with high-frequency, low-amplitude oscillations at a small gap between the nozzle exit and the resonator edge, which was observed in experiments, has been demonstrated. Pure-tone oscillations with maximum intensity occur when the resonator is placed in the region of the beginning of the second barrel, this observation being in good agreement with the data obtained by other authors. Subsequent increase in the nozzle-to-resonator distance leads to the emergence of subharmonics and multiple harmonics. Verification of gained numerical results with available experimental data is carried out.