Application of the Harmonic Balance Method to Calculate the First Booster Stage Tonal Noise

The results of the numerical investigation of the tone noise of the first booster stage of a high bypass ratio turbofan in the far field in the approach (landing) operational conditions are presented. The study is performed using the frequency domain numerical method of multistage turbomachines tonal noise simulation, developed at the Baranov Central Institute of Aviation Motors (CIAM). A variant of the method suitable for the calculations in a nonlinear setup is used. The calculation is performed for several blade passages in each row. The harmonic balance method for multitonal disturbances with a frequency mapping is implemented. The results of the calculations are compared with the results of the calculations in the time domain, presented in the previous paper (they were also performed in a nonlinear setup) and with the experimental data obtained at the CIAM acoustic test facility. In general, satisfactory correspondence is found between the data in both cases. The results can be treated as an argument for the validity of the proposed nonlinear frequency domain method of the multistage turbomachinery tone noise calculations.