Numerical Investigation of the Effect of Clocking on Tonal Noise of First Two Booster Stages of Turbofan Engine

The article presents the results of a numerical investigation of the clocking, which is circumferential indexing of rotor or stator blade rows, and its effect on tonal noise for the first two booster stages of a turbofan engine low-pressure compressor. Calculations are performed for several relative positions of both rotor blade rows and stator blade rows. The considered computational model includes a row of fan rotor blades, rows of rotor blades, and rows of stator blades corresponding to the first two booster stages, as well as a row of inlet guide vanes of the booster. The stages have identical numbers of rotor blades and stator blades. The problem is to obtain the power of noise radiation and directivity patterns for the most intensive tones in operating mode N̄ = 58%. The investigation is performed using a method of multistage turbomachine tonal noise calculation in the frequency domain. The method is capable of modeling a change in the relative position of blade rows without any manipulations with a computational grid. The results of calculations show that clocking of rotor blade rows can change the power of radiation from the inlet by 4 dB. Clocking of stator blade rows has a negligible influence on the total power of noise radiation from the inlet, though for some circumferential modes, the power can change by more than 5 dB. The article was prepared based on materials of a report at the 10th Russian conference “Computational Experiment in Aeroacoustics and Aerodynamics,” September 16–21, 2024, Svetlogorsk, Kaliningrad oblast, http://ceaa.imamod.ru/ .