Balalaiev A. Characteristics of a tandem grid fan impeller of a turbofan engine

The thesis is devoted to solving the scientific and applied problem of increas-ing the efficiency of tandem blade rows of fans of turbofan engines by using grid tan-dem impellers. For the first time, the characteristics of a grid tandem impeller are obtained by the method of numerical experiment. It is shown that the use of grid tandem impellers provides an increase in the efficiency of the fan, increases its loading. The pressure ratio increases in the range of rotor rotation speed from 2202 ... 3010 rpm increases up to 10 % compared to a tandem impellers. Investigations of the frequency characteristics of natural vibrations of a single-row, equivalent to tandem row and grid tandem blades of the turbofan engine fan impellers are presented. It is shown that the use of tandem blades in the investigated fan without partitions is unacceptable due to the presence of natural vibration modes, in which the blades of the first and second rows intersect. It is shown that the use of grid tandem rotor blades improves rigidity and ensures reliable operation of the fan. The technique for selecting the parameters of a grid tandem turbofan engine fan impeller has been improved, taking into account the spectrum of natural vibration frequencies. The theory of tandem blade rows was further developed in terms of the study of grid tandem blade rows with a large elongation.