An Unsteady Ducted Fan Model for Rotorcraft Flight Simulation

This paper addresses the development of a high fidelity and efficient ducted fan simulation model for helicopter anti-torque and UAV lifting applications. The model developed is based on a nonuniform and unsteady ring vortex formulation for the duct and blade element model for the fan and, thus, can be applied for both steady and unsteady flight conditions. The formulation also addresses the duct-fan aerodynamic interaction. Effort was made to investigate the model through validation of the duct/fan model in both axial flight and crosswind conditions. The results obtained agreed well with the measured data, which validates the accuracy of the ducted fan model. The model developed has also shown that the formulation is computationally efficient and suitable for both engineering duct-fan design analysis and real-time flight simulation of manned or unmanned rotorcraft and VTOL air vehicles equipped with ducted fan devices.