Numerical investigation of the effect of clocking on tone noise of first two booster stages of turbofan engine

Results of numerical investigation of the effect of clocking, which is circumferential indexing of rotor or stator blade rows, on tone noise of the first two booster stages of turbofan engine low pressure compressor are presented. Calculations are performed for several relative positions of both rotor blade rows and stator blade rows. The computational model under consideration includes a row of rotor blades of the fan, rows of rotor blades and rows of stator blades corresponding to the first two booster stages and also row of inlet guide vanes of the booster. The stages have identical numbers of rotor blades and stator blades. A task is to obtain the power of noise radiation and directivity diagrams for most intensive tones at operational conditions = 58%. The investigation is performed using a method of multistage turbomachine tone noise calculation in frequency domain. The method is capable to model a change of relative position of blade rows without any manipulations with computational grid. The results of calculations show, that the clocking of rotor blade rows can change the power of radiation from inlet by 4 dB. The clocking of stator blade rows has negligible influence on the total power of noise radiation from inlet, though for some circumferential modes the power can change by more than 5 dB. The article was prepared based on the materials of the report at the 10th Russian conference “Computational experiment in aeroacoustics and aerodynamics”, September 16–21, 2024, Svetlogorsk, Kaliningrad region, http://ceaa.imamod.ru/.