How the Approach to Simulating Turbulence Influences the Accuracy of Predicting the Noise Level of a Bypass Turbojet Engine Fan

The study presents the results of how noise level prediction results are influenced by the approach to simulating turbulence when calculating the noise generated by the bypass fan stage. Numerical studies are performed for a model fan stage in the main operating modes, which determine its acoustic properties. Far-field noise level calculations were performed using a finite element method based on the mode composition of the generated noise. We analyze the influence of the turbulence model on the number and amplitudes of acoustic modes excited in the flow at the fundamental harmonics of the fan blade passing frequency. It is shown that simulation of the anisotropic turbulence of a flow when calculating the unsteady rotor–stator interaction makes it possible to obtain noise levels close to experimental ones.