A three-dimensional body-force model for nacelle-fan systems under inlet distortions

A steady-state three-dimensional body-force model is presented for nacelle-fan system modeling. The model is based on three-dimensional averaged governing equations that are rigorously derived from three-dimensional unsteady Reynolds-Averaged Navier–Stokes equations. The three-dimensional nature of the model provides intuitive advantages, in terms of both flow physics and implementations, in modeling inlet distortion problems. One application of this model is to predict the effects of the fan system under inlet distortion upon the upstream and downstream flow field of the fan system. This is particularly useful for nacelle designers. The proposed body force model is formulated and implemented without any knowledge of the fan blade geometry. Instead, fan performance data provided by engine suppliers are fed into the body force model to replicate/predict the fan characteristics and their interactions with the upstream flow field under inlet distortions. This approach is validated with inlet distortion data to demonstrate its capability in general off-design conditions.