A new harmonic balance approach using multidimensional tim

Abstract

Nonlinear frequency-domain methods have become a state-of-the-art technique for the numerical simulation of unsteady flows within multistage turbomachinery. Despite this success, it still remains a significant challenge to capture nonlinear interaction effects within configurations with multiple fundamental frequencies. To overcome this, a new harmonic balance approach based on multidimensional Fourier transforms in time is developed in this thesis. After a detailed presentation of the theory of the new method, the validity and the performance of the multidimensional approach is demonstrated by means of three representative test cases: a convergent-divergent duct under the influence of acoustic pressure disturbances, the well-established aeroelasticity test case Standard Configuration 10 in the presence of a periodic disturbance, as well as a modern low-pressure fan stage of a civil aero engine under the influence of a rotational asymmetric inlet distortion.