Development of an axial fan for local ventilation adjustable by the angle of impeller blades

The paper studies a modular axial fan with a diameter of 0.9 m with an impeller that has special blade attachment units that allow adjustment of the blade angles. It is possible to operate two fans sequentially to increase the pressure in the ventilation system, with the blade angles of each fan being different. In this modular operating mode, the aerodynamic characteristics of the joint operation of the fans are affected by both the presence of an inlet guide vane and the blade angles. Calculated aerodynamic characteristics are determined based on computational experiments for the fan both the with and without an inlet guide vane, as well as two fans connected in series. It is shown that in the case of different blade angles for two fans connected in series, a greater efficiency is achieved with the smaller blade angles of the second machine than the calculated angles. An aerodynamic calculation is performed of the transient operating mode of two fans connected in series and the frequencies of the forcing aerodynamically conditioned external forces are determined. Based on the conducted studies, a conclusion is made about the admissibility of regulating the blade angle of two machines connected in series.