Development and Evaluation of Reduced Order Models of On-Blade Control for Integrated Flight and Rotor Control

This paper considers a methodology for reduced order modeling of the aerodynamic effects of an on-blade trailing edge flap (TEF) actuator using artificial neural networks (NNET) from CFD analysis data. The fidelity of the NNET model is evaluated through comparisons with CFD results for selected sinusoidal TEF inputs. The developed NNET model is integrated into a comprehensive helicopter flight dynamics simulation model which incorporates an elastic blade and 33-state inflow representation. Linear time invariant (LTI) models that include both body and rotor states are extracted for a selected forward flight condition. The fidelity of the extracted LTI models is evaluated through comparisons with the nonlinear model in both time and frequency domains. For time domain evaluations, TEF inputs are taken to be similar to the on-blade control inputs considered in the past for vibration and noise control studies. For frequency domain evaluations, frequency responses of fixed system hub loads to a single blade TEF input are used. The model evaluation results presented demonstrate the viability of the proposed approach.