Resumen
A new shape of the tandem blade with an improved arrangement of profiles, in relation to the known propellers, in which the profiles are located similar to those in the tandem wing of an airplane is developed. A new arrangement of profiles along the height of the blade is proposed. The basis for the design was the location of the profiles according to the type of tandem blade rows of compressors and fans. Such an approach made it possible to eliminate the aerodynamic shadowing of the blades and increase the aerodynamic loading. To join the blades in the final part, a spiral tip connector is used, which allowed to significantly reduce the secondary end losses by preventing the formation of the tip vortex.To study the characteristics of tandem propellers and the structure of gas-dynamic flows around them, a computational model of the propeller in a periodic formulation was developed, which significantly reduced the calculation time. The simulation was carried out in the ANSYS CFX software package, which implements an algorithm for solving non-stationary Reynolds averaged Navier-Stokes equations closed by the SST turbulence model. As a result of the simulation, the characteristics of the tandem propeller were obtained, which confirmed the correctness of the chosen approach for the design of the tandem blade. The efficiency of the developed propeller reaches 75 % in the design mode, which is a very good indicator for small propellers operating at low Reynolds numbers. For comparison, the efficiency of classic propellers with similar geometric characteristics is in the range of 50?60 %. When using the tandem propeller with joined blades as a pusher propulsion, a decrease in its thrust by 3?4 % was observed, which is due to the formation of a vacuum zone in the hub part and in the spinner area