AN EVALUATION OF LINEARIZED VORTEX THEORY AS APPLIED TO SINGLE AND MULTIPLE ROTORS HOVERING IN AND OUT OF GROUND EFFECT

摘要

A reexamination is made of the effect of the assumptions of linearized vortex theory as applied to hovering rotors. It is shown that differences between the actual and the simplified theoretical wake patterns may lead to large errors in the calculated flow, particularly at points outside the rotor wake. In particular, the results of hovering tests of a two-rotor configuration in ground effect do not show the large, favorable interference effects predicted by theory. Correlation of these results with available flow studies indicates that there are some regions of the flow field of a single rotor, primarily within the wake, where the theory yields reasonable qualitative results which can be used for ground-effect and download calculations.