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An evaluation of ground effect modelling for rotors in hover
Date Issued
01-01-2017
Author(s)
Abstract
A well-known phenomenon in rotorcraft, the ground effect, occurs when a rotor is at close proximity to the ground creating an obstruction to the trailing wake from the rotor. This results in an increase in thrust and a decreased inflow through the rotor disk, in turn affecting handling qualities. Until recently, analytical modelling of ground effect involved using empirical factors or method of images to account for the variation in thrust as a function of the elevation. The Morillo-Peters dynamic inflow model has now been known to satisfactorily predict the variations in rotor thrust for a rotor in ground effect. Although the variation in thrust seem to agree with empirical formulations, the model needs to be evaluated with experimental or computational simulations by comparing the variation of inflow over the rotor disk. An investigation on how closely the model predicts the inflow distribution is beneficial to future developments, considering the possibility of extending the model to other dynamic environments involving ground effect. This paper draws a comparison between the inflow models of Morillo, Ke Yu and Peters, Nowak and He, and a CFD package, RotCFD, for a hovering rotor in ground effect.