The purpose of this study is to determine the influence of the diameter of a subsonic conical nozzle on the generation of acoustic waves in a two-channel system. Three-dimensional numerical simulation of flow in the duct of an actual device was performed. A complete picture of the flow generated in the acoustic-convective drying system of the Institute of Theoretical and Applied Mechanics, SB RAS, was obtained. The results of the study show that to maintain the amplitude-frequency characteristics of the workflow with increasing diameter of the subsonic conical nozzle, it is necessary to reduce the settling chamber pressure. The numerically simulated amplitude-frequency characteristics of the acoustic flow generated in the working section of the drying system are in satisfactory agreement with the results of physical experiments.