Efficient simulation of inlet distortion in engine fan stage using nonlinear harmonic method

The nonlinear harmonic method (NLH) for efficiently simulating unsteady turbomachinery fluid dynamics in the frequency domain is described, and the details of its application to inlet distortion are discussed. The method capabilities are then demonstrated on the NASA transonic fan Stage 67 with a generic inlet distortion. Comparison of the results with the available experimental data confirms that the reconstructed unsteady flow solution obtained by the nonlinear harmonic method captures the main flow characteristics of the inlet distortion interaction with the fan stage such as the swirl associated with the upstream flow redistribution, the total pressure distortion transfer, and the generation of the total temperature distortion. The method offers a cost saving of two orders of magnitude compared to conventional time-domain unsteady methods for this type of applications.