ЧИСЕЛЬНЕ ДОСЛІДЖЕННЯ ВЛАСНИХ КОЛИВАНЬ ДВОРЯДНОЇ РОБОЧОЇ ЛОПАТКИ СТУПЕНЯ ОСЬОВОГО КОМПРЕСОРА

One of the important issues in engine building is to improve the efficiency of axial compressors. The use of tandem blade rows improves the aerodynamic characteristics of the compressors. However, the issues related to the strength characteristics of tandem blade rows, primarily the study of natural vibrations and natural vibration modes of the blades, remain not fully resolved. The purpose of this work is to evaluate the pressure ratio of an axial compressor stage with a single and equivalent tandem impeller, as well as to compare the modes of natural vibrations of a single and an equivalent tandem rotor blade. A numerical experiment was chosen as the research method. To simulate the flow in the stages of an axial compressor, the system of Navier-Stokes equations was used, which was closed by the SST turbulent viscosity model. For each individual blade row, a computational domain was constructed, consisting of a blade and an interblade channel. The computational area for three blade rows had about 13 million cells. Air was chosen as the working fluid under normal atmospheric conditions. Based on the results of modeling the flow in the stages, the values of the pressure ratio were obtained. The analysis of the results obtained shows that the use of a tandem impeller makes it possible to increase the pressure ratio in the compressor stage by 1.6 ... 5.6% in the considered ranges of the relative rotational speed and values of the axial velocity coefficient. Compressor impellers are among the most stressed structural elements of aircraft gas turbine engines. The overall vibration intensity is significantly increased by the vibrations of the rotor blades and disks. Using a numerical experiment, the spectra of natural frequencies and natural vibration modes of a single and equivalent tandem impeller blade are obtained. The data obtained show that the spectrum of natural vibration frequencies of single and equivalent tandem blades is significantly different. The data obtained must be taken into account when designing compressors with tandem impellers. There are the natural vibration modes of the tandem blade where the blades of the first and second rows intersect. [ABSTRACT FROM AUTHOR]