###### Abstract
Figure 9c shows that an increase in flow characteristics through the system also had virtually no effect on the gas-dynamic structure of the flow in a vertical conical diffuser when air is supplied through a triangular channel, significant stagnant zones can be recorded in the corners of the diffuser, and there is a uniform central flow with complete filling of the volume in the upper part. The data obtained indicate the stable influence of longitudinal vortex structures in profiled channels, which retain their effect on the distribution of air in a vertical diffuser at various air flow rates (velocities). Figure 10 demonstrates the flow structure in a vertical diffuser for channels with various configurations at an air flow rate through the system of \(q=0.057\) m\({}^{3}\)/s. Figure 10a illustrates that an additional increase in air flow (velocity) through the system led to a decrease in stagnant zones in the corners of the diffuser. Accordingly, we can  
Figure 1:3 Thermograms of the flow structure in a vertical diffuser when air is supplied through channels with different cross-sectional shapes (flow rate through the system \(q=0.057\) m\({}^{3}\)/s): (**a**) circle; (**b**) square; (**c**) triangle. Figure 1:4 Thermograms of the flow structure in a vertical diffuser when air is supplied through channels with different cross-sectional shapes (flow rate through the system \(q=0.047\) m\({}^{3}\)/s): (**a**) circle; (**b**) square; (**c**) triangle. conclude that stagnant zones decrease with increasing flow (velocity) through the system under consideration (channel diffuser). Figure 10b shows that an additional increase in flow rate through the square channel did not cause any changes in the air distribution inside the vertical diffuser. Figure 10c demonstrates that an additional increase in flow characteristics through the system did not cause any changes in the flow structure in the diffuser when air was supplied through a triangular channel. It should be noted that when studying the flow structure with air supply through a triangular channel, the mesh was stretched not through the centre of the triangle but with a significant shift to one of the corners. This is due to limitations in the geometric dimensions of the diffuser and supply channel. Therefore, there are plans to refine the data for this design by using other optical methods (in particular, through a PIV measurement system). The following presents data on the flow structure in a vertical diffuser with nozzle air supply. For example, Figure 11 illustrates the flow structure in a vertical diffuser for a nozzle air supply through tubes with different cross-sections at a flow rate through the system of \(q=0.018\) m\({}^{3}\)/s. Figure 11a shows that when air is supplied through a nozzle and round tubes, intense air movement can be recorded at the base of the diffuser. At the same time, there are no stagnant zones in the corners of the diffuser. The further distribution of air flow along the height of the diffuser is almost uniform, with some deviation towards the right side. From Figure 11b it can be seen that with nozzle air supply through square tubes, there is also an intense flow movement at the base of the diffuser, with further uniform distribution of air throughout the entire volume of the diffuser. Thus, it can be concluded that the use of a square nozzle tube did not have a significant effect on flow structure in the vertical conical diffuser. Figure 11c demonstrates that the use of triangular nozzle tubes causes the most uniform distribution of air throughout the entire volume of the diffuser compared to other nozzle tube configurations. In this case, intense air movement can be seen along the vertical axis over almost the entire height of the diffuser (the shape of this movement resembles a 'carrot'). A pronounced central flow in the diffuser is not created when using a nozzle air supply. The jet collapse can be seen at the very beginning of the diffuser (square tubes), in the middle part (round tubes), or in the upper part (triangular tubes).