Air flow in air jet weaving machines is complicated: it is complicated: it is unsteady, turbulent, and can be compressible or incompressible depending on the velocity. A spearated flow model is developed to simulate air flow through the guide channel, which is half open and corrugated. Subsonis air flow in the guide channel is investigated as a simplified model of air flow in a single nozzle air-jet filling insertion system. The drag coefficient in the guide channel and propelling force acting on the yarn are calculated. Theoretical predictions of drag coefficient and propelling force are in good agreement with experimental data obtained for the same conditions.